More Important Topics of Bioms Cylinder

Forest Biomes represent the largest and most ecologically complex systems. They contain a wide assortment of trees, plants, mammals, reptiles, amphibians, invertebrates, insects and micro-organisms which vary depending on the zone's climates.

Sadly, boreal and rainforest biomes are being cut down at

an alarming rate, with hundreds of species of plants and animals disappearing from the planet on a daily basis.

Forests represent a third of the earth's land, and are found in the four corners of the globe. The major attribute of the forest biome is its trees. While they are different from animals in many ways, they share one common characteristic: they breathe. While humans and animals breathe in oxygen and exhale carbon dioxide, trees take in carbon dioxide and produce oxygen.

Deforestation represents a great threat to the future of the earth's atmosphere, and the only way this can be avoided is by careful management of this resource. Once a tree is cut down, another should take its place, but there is still too large a number of trees being cut down as opposed to the number of trees being planted.

Boreal, or Taiga biomes

The largest of the land biomes is the boreal, or Taiga biome. Taiga biomes can be found in areas with shorter, warm summers and long winters; there are Taiga Biomes in Europe, Asia, Siberia, and North-America. Because of the cold climates, plant life in the boreal forest is sturdy, consisting mainly of evergreens and other resilient vegetation.

Because the forests' canopy is dense, forest floor vegetation is thin. Animal life in the boreal forest consists mainly of birds and mammals, such as deer, wolves, and various rodents, and very few reptiles. Most of the boreal forests' creatures are well adapted to the cold climate, and hibernate during the long winters.

Temperate Deciduous

Temperate deciduous forest are a close relative of the Taiga biome, and can be found in areas with a milder, shorter winter season. In addition to evergreens, trees in the temperate forest include maple, elm, oak, cedar and other trees which shed their leaves in the fall.

The temperate forest's soil in richer than that of the boreal forests' and features a larger assortment of forest floor plan life; this is also due to the fact that the forests' canopy is thinner, allowing more light and heat to penetrate, permitting photosynthesis in the forest floor plants, and the survival of smaller, and cold blooded animals such as garter snakes, turtles, and a few amphibians. Again, several of the temperate forests' species hibernate, and/or burrow in the ground to pass the winter months.

Other forests which fall between the boreal and temperate classification include moist evergreen forests, moist evergreen and broad-leaf forests, dry evergreen forests, mediterranean forests, temperate evergreen forests, and temperate broad-leaf forests.

Tropical, or rainforest

The rainforest is the most ecologically rich of the world's biomes. Rainforest occupy only 75 of earth's land areas and are generally found at the equatorial level of the planet. Daylight in the rainforest lasts for 12 hours, there is no winter, and the seasons can best be described as rainy, or dry, with little change in temperature.

The rainforest is host to the largest variety of life forms in all of nature, with thousands of different species of trees, plants, flowers, mammals, birds, reptiles, amphibians, insects, invertebrates and micro-organisms. Many of the animals in the rainforest are highly adapted to their highly competitive and diverse environment, having developed camouflage or strong defenses, which are always heralded by colorful markings.

While the rainforest isn't ideally suited for human habitation, it has been the home of tribes such as the Yanomamo in South-America, and Pamagirri in Australia. Perhaps, they too have survived by adapting to their environment, but it is the so-called civilized world which poses the biggest threat to the rainforest, aggressive logging, and clearcutting to make way for plantations have endangered the rain forest's animal and plant life, and brought on irreparable damage to the earth's atmosphere. Close to 80,000 acres of rainforest are destroyed each year, and over 50,000 species of life forms become extinct.

Find out what you can do to help preserve this important biome.

The other forests which fall into the rainforest category are the seasonal rainforest, with it's very humid tropical area subject to a short dry season, the evergreen rainforest, which does not have a dry season, the monsoon rainforest, where the dry season is prolonged in proportion to the lower amount of rain, and finally, the semi-evergreen rainforest, which is similar to the seasonal rainforest, but has a longer dry season.

Further subdivisions of this group are determined by seasonal distribution of rainfall.

Common characteristics of bears include a short tail, excellent senses of smell and hearing, five un-retractable claws per paw, and long, dense, shaggy fur. Bears have a large body with powerful limbs. They are capable of standing up on their hind legs. They have broad paws, long snouts, and round ears.

Their teeth are used for defense and tools and depend on the diet of the bear. Their claws are used for ripping, digging, and catching. A bear's eyesight is probably similar in acuity (sharpness) to the human eye. Black bears, and likely other bears, have color vision to help them identify fruits and nuts.

Depending on the species, bears can have 32 to 42 teeth.

Bear teeth are not specialized for killing their prey like those of cats. Normal canine teeth in a carnivore are generally large and pointed used for killing prey, while bears' canine teeth are relatively small and typically used in defense or as tools. Bears' molar teeth are broad, flat and are used to shred and grind plant food into small digestable pieces.

Bears have four limbs that end in paws. Each paw has five long, sharp claws that are unretractible, unlike cats. These claws can be used to climb trees, rip open termite nests and beehives, dig up roots, or catch prey, depending on the species. While most carnivores tend to walk on their toes in a way that is adapted for speed, bears have a plantigrade stance.

They walk with their weight on the soles of their hindfeet, with the heel touching the ground, while the toes of the forefeet are used more for balance. Although slower than most carnivores, a running bear can reach speeds of up to 50 km/h (30 mph). They are also stronger than most carnivores and their limbs are more flexible and agile.

A bear's fur is long and shaggy. Fur color varies among species, ranging from white, blonde or cream, black and white, to all black or all brown. Colors of a bear's fur can also vary within species. For example, American black bears may be black, brown, reddish-brown, or bluish-black. Several species, such as the sun bear and spectacled bear have a light-colored chest with facial markings.

In all bear species, males are larger than females, but the difference between sexes varies and is greatest in the largest species. Large male polar bears may weigh twice as much as females, while smaller male and female bears are much more similar in weight. A bear's life span seems to last about 25 to 40 years. Bears living in the wild tend to die younger than their zoo-counterparts.

Habitats

Bears live in a variety of habitats from the tropics to the Arctic and from forests to snowfields. They are mainly omnivorous, although some have a more specialised diet, such as polar bears. They eat lichens, roots, nuts, and berries. They can also go to a river or other body of water to capture fish. Bears will commonly travel far for food. Hunting times are usually in the dusk or the dawn except when humans are nearby.

Behavior

Bears mostly live alone, except for mothers and their cubs, or males and females during mating season. Bears form temporary groups only when food is plentiful in a small area. Alaskan brown bears group in the same area to feed on salmon during the annual salmon runs, when the fish swim upriver to reach their spawning grounds. Other bears may live alone but exist in a social network.

A male and female may live in an overlapping home range, each defending their range from other bears of the same mother sex. Male young usually leave their mothers to live in other areas, but females often live in an area that overlaps that of their mother.

Bears travel over large territories in search of food, remembering the details of the landscape they cover. They use their excellent memories to return to locations where food was plentiful in past years or seasons. Most bears are able to climb trees to chase prey or gain access to additional vegetation. The only exceptions are polar bears and large adult brown bears, whose heavy weight makes it difficult to climb trees.

Some of the large species, such as the polar bear and the grizzly bear, are dangerous to humans, especially in areas where they have become used to people. For the most part, bears are shy and are easily frightened of humans. They will, however, defend their cubs ferociously.

Reproductive behavior

The bear's courtship period is very brief. Bears reproduce seasonally, usually after a period of inactivity similar to hibernation. Cubs come out toothless, blind, and bald. The cubs, usually born in litters of 1–3, will stay with the mother for six months. They will be fed by milk at first and will start hunting with the mother in three months. Then, they are weaned.

However, they will still remain nearby for three years. The cubs reach sexual maturity at seven years. Normally, bears are very solitary and will not remain close together for long periods of time.

Bears and Humans

Despite being large animals, bears often coexist in surprisingly close proximity with humans. Despite their large size, bears, like many other forest animals, are adept at moving through wooded or rugged terrain without detection.

Bears will generally avoid contact with humans, and are usually aware of a human's presence long before the human is aware of the bear. As a result, encounters are typically avoidable and rare. However, bears are opportunistic feeders, and will generally take food where it is available. When humans provide feeding opportunities, such as left out garbage, food stored outside, or deliberate feeding, the chance of confrontation escalates.

As a bear begins to associate human presence with food, it may lose its shyness and become a potentially dangerous pest. The loser in these situations is almost always the bear, and many are killed every year as a result of human carelessness.

Conflicts may also arise in situations where the bear regards a human as an immediate threat to itself, its cubs, or food cache (which is one reason that found animal carcasses should be avoided). In a chance encounter with a bear, the best course of action is usually to back away slowly in the direction that you came, speaking in a loud, calm tone to make sure the bear is aware of your presence and will not be caught off guard.

The bear will rarely become aggressive and approach you. In order to protect yourself, some suggest passively lying on the ground and waiting for the bear to lose interest. Another approach is to constantly maintain an obstacle between you and the bear, such as a thick tree or boulder. A person is much more agile and quick than a bear allowing him or her to respond to a bear's clockwise or counter-clockwise movement around the obstacle and move accordingly.

The bear's frustration will eventually cause disinterest. One can then move away from the bear to a new obstacle and continue this until he or she has created a safe distance from the bear. When encountering a bear, one should never look directly into the bear's eyes. This action can be misconstrued by many wild animals as an aggressive act.

Other

Many bears of northern regions are assumed to hibernate in the winter. In medieval times it was believed that they died and were reborn in the spring. While many bear species do go into a physiological state called hibernation or winter sleep, it is not true hibernation. In true hibernators, body temperatures drop to near ambient and heart rate slows drastically, but the animals periodically rouse themselves to urinate or defecate and to eat from stored food.

The body temperature of bears, on the other hand, drops only a few degrees from normal and heart rate slows only slightly. They do not wake normally during this "hibernation", and therefore do not eat, drink, urinate or defecate the entire period. Higher body heat and being easily roused may be adaptations, because females bear cubs during this winter sleep.

Laws have been passed in many areas of the world to protect bears from hunters or habitat destruction. Bears in captivity have been to be trained to dance, box, or ride bicycles; however, this use of the animals became controversial in the late 20th century. In cartoons, circus bears are frequently depicted riding unicycles.

The brown bear is Finland's national animal. The black bear is the state animal of West Virginia in the United States.

Kodiak bears are the largest type, and in fact one of the largest extant carnivores, though polar bears are the heaviest. Sun bears are the smallest, only a bit smaller than the average person.

"scaly-tailed flying squirrels". The word squirrel comes from the Old French esqurial, which itself comes from the Vulgar Latin word scuriolus (squirrel).

Typical squirrels include the European Red Squirrel Sciurus vulgaris, the Fox Squirrel S. niger, the Eastern Gray Squirrel S. carolinensis, the Western Gray Squirrel S. griseus, the Douglas Squirrel Tamiasciurus douglasii, and the American Red Squirrel Tamiasciurus hudsonicus.

The "Black Squirrel" is actually a variant of the Eastern Gray Squirrel. Although considered rare in many areas, it is the dominant variety in most of Ontario, Quebec, and certain areas of the Northeastern United States but also as far south as Maryland and Virginia. It is thought that the black variant developed its dark coat to better absorb heat in colder climates.

In the United Kingdom, a colony of black squirrels has existed around the town of Letchworth Garden City for many years. Black squirrels, appearing to be identical to the red squirrels in the area, are also fairly common in some communities in southwestern Iowa, with a large population of black squirrels in Council Bluffs, Iowa. These large black squirrels have also been seen in Manilla and Missouri Valley in Iowa and Omaha, Nebraska.

The Red Squirrel populations in Britain, Ireland, and, more recently, northern Italy, have declined and become regionally extinct in recent decades, primarily because of competition from Gray Squirrels (introduced from North America), but also habitat loss. Conservation efforts include preserving and planting the conifer forests that Red Squirrels prefer. The recent colonisation of mainland Europe from Italy by Gray Squirrels is expected to result ultimately in the extinction of the Red Squirrel over most of Europe.

One well-known trait of some species of squirrel is the gathering and storing of nuts for the winter. These squirrels are scatter-hoarders, i.e. they will gather nuts and store them in any accessible hiding place, usually by burying them. Recent research shows that they have excellent memories for the locations of these caches.

Another characteristic trait of several types of squirrels, especially ground squirrels, is their tendency to rise on their hind legs and curl their paws flat against their chests when they sense any kind of danger. They will then survey their surrounding territories. If they feel that they are in peril, they will often send the warning call, a loud screeching sound, to alert other squirrels. Then there is a mad rush to the burrow.

Unlike rabbits or deer, squirrels cannot digest cellulose, and must rely on foods rich in protein, carbohydrates, and fat. Early spring is the hardest time of year for squirrels, as buried nuts begin to sprout and are no longer available, but new food sources have not become available yet. During these times squirrels rely heavily on the buds of trees, in particular, those of the Silver Maple.

Despite the popular impression, squirrels are actually omnivores; as well as eating a wide variety of plant food, including nuts, seeds, fruits, fungi (for example, mushrooms), and green vegetation, they also eat insects, eggs, and even small birds, smaller mammals, and frogs. It is also a common occurrence that these foods replace nuts in some of the tropics. There has even been a report of squirrels eating dogs.

Squirrels are generally clever and persistent animals; in residential neighborhoods they are notorious for eating out of bird feeders, digging in potted plants either to bury or recover seeds, and for setting up house in sheltered areas including attics. While many companies sell bird feeders which are supposedly "squirrel-proof", most of them in fact are not.

Squirrels are sometimes also pests because they chew on various edible and inedible objects; the habit helps keep the squirrel's teeth sharp and also wears them down (many rodents' teeth grow continuously). Homeowners in areas with a heavy squirrel population must keep attics and basements carefully sealed to prevent property damage caused by nesting squirrels.

Some homeowners resort to more humane ways of dealing with this, such as collecting and planting fur from pets (e.g domestic cats and dogs) in attics. This fur will indicate to nesting squirrels that a potential predator roams and will encourage evacuation. Fake owls and scarecrows are generally ignored by the animals, and the best way to prevent chewing on an object is to coat it with something to make it undesirable: for instance a soft cloth or chile pepper paste or powder. Squirrel trapping is also practiced to remove them from residential areas.

Squirrels can be trained to be hand-fed. Because they are able to cache surplus food, they will take as much food as you put out. If a person starts to feed one, that squirrel will come back day after day to get its food. Squirrels living in parks and campuses in cities have learned long ago that humans are typically a ready source of food. Hand feeding is not recommended, however, because squirrels may carry plague or other animal-borne diseases. Even if they do not carry disease, they often have a hard time telling fingertips from food, and bites are painful.

Squirrels are often the cause of electricity outages. The animals will enter transformers or capacitors looking for food. The squirrels are then electrocuted and cause a power surge that shorts equipment. Squirrels have brought down the high-tech NASDAQ stock market twice, and were responsible for a spate of power outages at the University of Alabama. They will often chew on tree branches to sharpen their teeth, but cannot tell the difference between a tree branch and a live power line. Rubber plates are sometimes used to prevent access to these facilities.

Squirrels as Food

Squirrel meat, until recent times, was considered a favored meat in certain regions of the United States where it can be listed as wild game. This is evidenced by extensive recipes for its preparation found in cookbooks including the Joy of Cooking. Squirrel meat can easily be exchanged for rabbit or chicken in recipes with its light red or pink flesh which has only a slight game taste.

Fox terminology is different from that used for most canids. Male foxes are known as dogs, tods or reynard, females are

referred to as vixens, and their young are called kits or cubs, as well as pups. A group of foxes is a skulk. The eponymous name 'Charlie' is derived from Charles James FOX who was a disliked landowner in the eighteenth century.

With most species roughly the size of a domestic cat, foxes are smaller than other members of the family Canidae, such as wolves, jackals, and domestic dogs. Recognizable characteristics also include pointed muzzles and bushy tails. Other physical characteristics vary according to their habitat. For example, the Desert Fox has large ears and short fur, whereas the Arctic Fox has small ears and thick, insulating fur.

Unlike many canids, foxes are not pack animals. They are solitary, opportunistic feeders that hunt live prey (especially rodents). Using a pouncing technique practiced from an early age, they are usually able to kill their prey quickly. Foxes also gather a wide variety of other foods ranging from grasshoppers to fruit and berries.

Foxes are nearly always extremely wary of humans, and are not kept as pets, but the Silver Fox was successfully domesticated in Russia after a 45 year selective breeding program. However, foxes are to be readily found in cities and domestic gardens.

The lemon (Citrus × limon) is a hybrid citrus tree of cultivated origin. The fruit are used primarily for their juice, though the pulp and rind (zest) are also used, primarily in cooking or mixing.

Lemon juice is about 5% citric acid, which gives lemons a sour taste and a pH of 2 to 3. This acidity makes lemon juice a cheap, readily available acid for use in educational

chemistry experiments.

A lemon tree can grow up to 6 m (20 ft), but they are usually smaller. The branches are thorny, and form an open crown. The leaves are green, shiny and elliptical-acuminate. Flowers are white on the outside with a violet streaked interior. On a lemon tree, flowers and ripe fruits can be found at the same time. There are several varieties of lemon including Eureka,

Lisbon and the Meyer lemon, which is thought to be a hybrid.

Cultivation

Lemons grow in tropical and sub-tropical climates and cannot withstand frosts and very cold temperatures. Their favored temperature is between 15–30 °C (60–85 °F). They thrive in fertile soils and ample quantities of sunlight. Propagation is often by grafting as the stock is vulnerable to cankers and dry rot.

Lemons are grown commercially in Spain, Portugal and other Mediterranean countries, Argentina, Brazil and the United States. They can be grown as plants in the garden as well as in containers if they are pruned to keep a small form.

History

The lemon is a cultivated hybrid deriving from wild species such as the citron and mandarin. When and where this first occurred is not known. The citron, apparently the fruit described in Pliny's Natural History (XII, vii.15) as the malum medicum — the "medicinal fruit" — seems to have been the first citrus fruit known in the Mediterranean world.

Depictions of citrus trees appear in Roman mosaics of North Africa, but the first unequivocal description of the lemon, is found in the early tenth-century Arabic treatise on farming by Qustus al-Rumi. At the end of the twelfth century, Ibn Jami’, personal physician to the great Muslim leader Saladin, wrote a treatise on the lemon, after which it is mentioned with greater frequency in the Mediterranean. However, it is believed that the first lemons were originally cultivated in the hot, semi-arid Deccan Plateau in Central India.

The origin of the name "lemon" is through Persian (???? Limu), akin to the Sanskrit nimbuka. They were cultivated in Genoa in the mid-fifteenth century, and appeared in the Azores in 1494. More recent research has identified lemons in the ruins of Pompeii. Lemons were once used by the British Royal navy to combat scurvy, as they provided a large amount of vitamin C.

Temperate evergreen forests are common in the coastal areas of regions that have mild winters and heavy rainfall, or inland in drier climates or mountain areas. Many species of trees inhabit these forests including cedar, cypress, douglas-fir, fir, juniper, kauri, pine, podocarpus, spruce, redwood and yew. The understory also contains a wide variety of herbaceous and shrub species.

This region does not support deciduous trees or flowering plants, since the climate does not support insects. Coniferous forests also have limited rainfall, requiring deciduous trees to shed their leaves soon after producing them. This makes angiosperms incapable of whethering interspecific competition with conifers.

The rainforest is the most ecologically rich of the world's biomes. Rainforest occupy only 75 of earth's land areas and are generally found at the equatorial level of the planet. Daylight in the rainforest lasts for 12 hours, there is no winter, and the seasons can best be described as rainy, or

dry, with little change in temperature.

The rainforest is host to the largest variety of life forms in all of nature, with thousands of different species of trees, plants, flowers, mammals, birds, reptiles, amphibians, insects, invertebrates and micro-organisms. Many of the animals in the rainforest are highly adapted to their highly competitive and diverse environment, having developed camouflage or strong defenses, which

are always heralded by colorful markings.

While the rainforest isn't ideally suited for human habitation, it has been the home of tribes such as the Yanomamo in South-America, and Pamagirri in Australia.

erhaps, they too have survived by adapting to their environment, but it is the so-called civilized world which poses the biggest threat to the rainforest, aggressive logging, and clearcutting to make way for plantations have endangered the rain forest's animal and plant life, and brought on irreparable damage to the earth's atmosphere. Close to 80,000 acres of rainforest are destroyed each year, and over 50,000 species of life forms become extinct.

Find out what you can do to help preserve this important biome.

The other forests which fall into the rainforest category are the seasonal rainforest, with it's very humid tropical area subject to a short dry season, the evergreen rainforest, which does not have a dry season, the monsoon rainforest, where the dry season is prolonged in proportion to the lower amount of rain, and finally, the semi-evergreen rainforest, which is similar to the seasonal rainforest, but has a longer dry season.

Further subdivisions of this group are determined by seasonal distribution of rainfall.

It has almost no tail or external ears, and its head is slightly rounded with a blunt nose. The body is covered with long and course hair.

Very small green algae sometimes live mutualistically in the pits of the hair, which gives the sloth an overall greenish appearance that serves as camouflage. Male sloths have a bright yellow or orange patch on the back.

The females have two mammae in the chest region. The three-toed sloth is armed with long, compressed, arched, hollowed claws, of which the middle claw is the largest.

Bradypus tridactylus grows to a length of between 1.5 and 2.5 ft. The limbs

are long and weak, with anterior extremities that are nearly double the length of the posterior. The three-toed sloth has 9 neck vertebrae, giving it extreme flexibility. The three-toed sloth can hang so securely with its hooklike claws that it even falls asleep in this position. A sloth may even stay suspended in the trees for some time after it dies.

Alligators differ from crocodiles principally in having wider and shorter heads, with more obtuse snouts; in having the fourth, enlarged tooth of the under jaw received, not into

an external notch, but into a pit formed for it within the upper one; in lacking a jagged fringe which appears on the hind legs and feet of the crocodile; in having the toes of the hind feet webbed not more than half way to the tips, and in tolerance to salinity, alligators strongly preferring fresh water, while crocodiles can tolerate salt water due to specialized glands for filtering out salt.

In general, the more dangerous crocodilians to human beings tend to be crocodiles rather than alligators. The Black Caiman (Melanosuchus niger) is a threatened species, related to alligators. It is a carnivorous reptile that lives along slow-moving rivers and lakes, in the seasonally flooded savannas of the Amazon basin, and in other freshwater habitats in South America. Once common, it was hunted to near extinction primarily for its commercially valuable hide.

The black caiman can grow to about 6 meters (20 feet) in length, and is both the largest alligator and the Amazon's largest predator. They eat fish, including piranhas, birds, turtles, and land-dwelling animals like the capybara and deer when they come to the water to get a drink.

Larger specimens can take puma and jaguar. Their teeth are designed to grab but not rip, so they swallow their food whole after drowning it. Immature specimens eat crustaceans and insects. The caiman's excrement was once a substantial food source for the plankton which form the base of the aquatic Amazonian food chain, and their rarity has thus led to a concomitant decline of many species, including some important food species.

The black caiman has a bony ridge over red eyes, and black, scaly skin. The skin coloration helps with camouflage during its nocturnal hunts, but may also help absorb heat (See thermoregulation).

In December, females build a nest of soil and vegetation, which is about 1.5 meters (5 feet) across and 0.75 meters wide (2.5 feet). They lay from 50 to 60 eggs, which hatch in about six weeks. They sometimes eat their young.

Their main predator is humans, who hunt them for leather or meat.

People who study or collect butterflies (or the closely related moths) are called lepidopterists. Butterfly watching is growing in popularity as a hobby. Another old term for a

lepidopterist is aurelian. Presently butterflies are classified in two superfamilies, Hesperioidea, consisting of the 'skippers' and Papilionoidea or 'true butterflies'. These are sister taxa, so the butterflies collectively are thought to constitute a true clade. Some modern taxonomists place them all in superfamily Papilionoidea, distinguishing the skippers from the other butterflies

at the series level only. In this system, Papilionoidea consists of the series Hesperiiformes (with one family only, the skipper family Hesperiidae) and the series Papilioniformes (with five families).

Parrots are zygodactyl, like woodpeckers, having 4 toes on each foot – two front and two back.

Their native habitats are the forests, especially rain forests, of Mexico and Central and South America. They are locally also known as Guacamayos in Spanish and Arara in Portuguese.

In botany, deciduous plants, principally trees and shrubs, are those that lose all of their foliage for part of the year. In some cases, the foliage loss coincides with the incidence of

winter in temperate or polar climates, while others lose their leaves during the dry season in climates with seasonal variation in rainfall. The converse of deciduous is evergreen. Many deciduous plants flower during the period when they are leafless, as

this increases the effectiveness of pollination. The absence of leaves improves wind transmission of pollen in the case of wind-pollinated plants, and increases the visibility of the flowers to insects in insect-pollinated plants. This strategy is not without risks, as the flowers can be damaged by frost, or in dry season areas, result in water stress on the plant.

The conifers, division Pinophyta, also known as division Coniferae, are one of 13 or 14 division level taxa within the Kingdom Plantae. They are cone-bearing seed plants with vascular tissue; all extant conifers are woody plants, the great majority being trees with just a few being shrubs.

Typical examples of conifers include cedars, cypresses, douglas-firs, firs, junipers, kauris, larches, pines, redwoods, spruces, and yews. Species of conifers can be found growing naturally in almost all parts of the world, and

are frequently dominant plants in their habitats, as in e.g. the taiga.

Conifers are of immense economic value, primarily for timber and paper production; the wood of conifers is known as softwood.

The division name Pinophyta conforms with the rules of the ICBN, which state (Art 16.1) that the names of higher taxa in plants (above the rank of family) are either formed from the name of an included family, in this case Pinaceae (the pine family), or are descriptive. In the latter case the name for the conifers (at whatever rank is chosen) is Coniferae (Art 16 Ex 2), which is also in widespread use. Older scientific names (no longer allowed) are Coniferophyta and Coniferales.

Commonly but erroneously, conifers are considered equivalent to the Gymnosperms, as in areas with a temperate climate conifers are often the only commonly occurring gymnosperms. However, these are two quite different groupings; conifers are the largest and economically most important component group of the gymnosperms, but nevertheless only one of the four component groups.

It is not clear if gymnosperms are a natural group; it may well be polyphyletic as the component groups like the cycads and ginkgos are quite distinct plants (see diagram below), though some recent research does indicate they may be monophyletic.

The division Pinophyta consists of just one class, Pinopsida, which includes both living and fossil taxa. Subdivision of the living conifers into two or more orders has been proposed from time to time. The most commonly seen in the past was a split into two orders, Taxales (Taxaceae only) and Pinales (the rest), but recent research into DNA sequences suggests that this interpretation leaves the Pinales without Taxales as paraphyletic, and the latter order is no longer regarded as distinct.

A more accurate subdivision would be to split the class into three orders, Pinales containing only Pinaceae, Araucariales containing Araucariaceae and Podocarpaceae, and Cupressales containing the remaining families (including Taxaceae), but there has not been any significant support for such a split, with the majority of opinion preferring retention of all the families within a single order Pinales, despite their antiquity and diverse morphology.

The conifers are now accepted as comprising six to eight families, with a total of 65-70 genera and 600-650 species. The seven most distinct families are linked in the box above right and phylogenetic diagram left. In other interpretations, the Cephalotaxaceae may be better included within the Taxaceae, and some authors additionally recognise Phyllocladaceae as distinct from Podocarpaceae (in which it is included here).

The family Taxodiaceae is here included in family Cupressaceae, but was widely recognised in the past and can still be found in many field guides.

The conifers are an ancient group, with a fossil record extending back about 300 million years to the Paleozoic in the late Carboniferous period; even many of the modern genera are recognisable from fossils 60-120 million years old. Other classes and orders, now long extinct, also occur as fossils, particularly from the late Paleozoic and Mesozoic eras.

Fossil conifers included many diverse forms, the most dramatically distinct from modern conifers being some herbaceous conifers with no woody stems. Major fossil orders of conifers or conifer-like plants include the Cordaitales, Vojnovskyales, Voltziales and perhaps also the Czekanowskiales (possibly more closely related to the Ginkgophyta).

Morphology

All living conifers are woody plants, and most are trees, the majority having monopodial growth form (a single, straight trunk with side branches) with strong apical dominance. The size of mature conifers varies from less than one metre, to over 100 metres. The world's tallest, largest, thickest and oldest living things are all conifers. The tallest is a Coast Redwood (Sequoia sempervirens), with a height of 112.83 metres.

The largest is a Giant Sequoia (Sequoiadendron giganteum), with a volume 1486.9 cubic metres. The thickest, or tree with the greatest trunk diameter, is a Montezuma Cypress (Taxodium mucronatum), 11.42 metres in diameter. The oldest is a Great Basin Bristlecone Pine (Pinus longaeva), 4,700 years old.

The leaves of many conifers are long, thin and needle-like, but others, including most of the Cupressaceae and some of the Podocarpaceae, have flat, triangular scale-like leaves. Some, notably Agathis in Araucariaceae and Nageia in Podocarpaceae, have broad, flat strap-shaped leaves.

In the majority of conifers, the leaves are arranged spirally, exceptions being most of Cupressaceae and one genus in Podocarpaceae, where they are arranged in decussate opposite pairs or whorls of 3 (-4). In many species with spirally arranged leaves, the leaf bases are twisted to present the leaves in a flat plane for maximum light capture (see e.g. photo of Grand Fir Abies grandis). Leaf size varies from 2 mm in many scale-leaved species, up to 400 mm long in the needles of some pines (e.g. Apache Pine Pinus engelmannii).

The stomata are in lines or patches on the leaves, and can be closed when it is very dry or cold. The leaves are often dark green in colour which may help absorb a maximum of energy from weak sunshine at high latitudes or under forest canopy shade. Conifers from hotter areas with high sunlight levels (e.g. Turkish Pine Pinus brutia) often have yellower-green leaves, while others (e.g. Blue Spruce Picea pungens) have a very strong glaucous wax bloom to reflect ultraviolet light.

In the great majority of genera the leaves are evergreen, usually remaining on the plant for several (2-40) years before falling, but five genera (Larix, Pseudolarix, Glyptostrobus, Metasequoia and Taxodium) are deciduous, shedding the leaves in autumn and leafless through the winter. The seedlings of many conifers, including most of the Cupressaceae, and Pinus in Pinaceae, have a distinct juvenile foliage period where the leaves are different, often markedly so, from the typical adult leaves.

Most conifers are monoecious, but some are subdioecious or dioecious; all are wind-pollinated. Conifer seeds develop inside a protective cone called a strobilus (or, very loosely, "pine cones", which technically occur only on pines, not other conifers!). The cones take from four months to three years to reach maturity, and vary in size from 2 mm to 600 mm long.

In Pinaceae, Araucariaceae, Sciadopityaceae and most Cupressaceae, the cones are woody, and when mature the scales usually spread open allowing the seeds to fall out and be dispersed by the wind. In some (e.g. firs and cedars), the cones disintegrate to release the seeds, and in others (e.g. the pines that produce pine nuts) the nut-like seeds are dispersed by birds (mainly nutcrackers and jays) which break up the specially adapted softer cones.

Ripe cones may remain on the plant for a varied amount of time before falling to the ground; in some fire-adapted pines, the seeds may be stored in closed cones for up to 60-80 years, being released only when a fire kills the parent tree.

In the families Podocarpaceae, Cephalotaxaceae, Taxaceae, and one Cupressaceae genus (Juniperus), the scales are soft, fleshy, sweet and brightly coloured, and are eaten by fruit-eating birds, which then pass the seeds in their droppings. These fleshy scales are (except in Juniperus) known as arils.

In some of these conifers (e.g. most Podocarpaceae), the cone consists of several fused scales, while in others (e.g. Taxaceae), the cone is reduced to just one seed scale or (e.g. Cephalotaxaceae) the several scales of a cone develop into individual arils, giving the appearance of a cluster of berries.

The male cones have structures called microsporangia which produce yellowish pollen. Pollen is released and carried by the wind to female cones. Pollen grains from living pinophyte species produce pollen tubes, much like those of angiosperms. When a pollen grain lands near a female gametophyte, it undergoes meiosis and fertilizes the female gametophyte.

The resulting zygote develops into an embryo, which along with its surrounding integument, becomes a seed. Eventually the seed may fall to the ground and, if conditions permit, grows into a new plant.

In forestry, the terminology of flowering plants has commonly though inaccurately been applied to cone-bearing trees as well. The male cone and unfertilized female cone are called "male flower" and "female flower", respectively. After fertilization, the female cone is termed "fruit", which undergoes "ripening" (maturation).

Life cycle

To fertilize the ovum, the male cone releases pollen that is carried on the wind to the female cone.

A fertilized female gamete (called a zygote) develops into an embryo.

Along with integument cells surrounding the embryo, a seed develops containing the embryo.

Mature seed drops out of cone onto the ground.

Seed germinates and seedling grows into a mature plant.

When mature, the adult plant produces cones.

Leaf persistence in evergreen plants may vary from only

just over a year (shedding the old leaves very soon after the new leaves appear), up to a maximum of 45 years in Great Basin Bristlecone Pine Pinus longaeva (Ewers & Schmid 1981). However, very few species show leaf persistence of over 5 years. One additional special case exists in Welwitschia, an African gymnosperm plant which produces only two leaves, which grow continuously

throughout the plant's life but gradually wear away at the apex, giving about 20–40 years' persistence of leaf tissue.

Reasons for being Evergreen

In warm tropical regions, most rainforest plants are evergreen, replacing their leaves gradually throughout the year as the leaves age and fall, whereas species growing in seasonally arid climates may be either evergreen or deciduous. Most warm temperate climate plants are also evergreen. In cool temperate climates, fewer plants are evergreen, with a predominance of conifers, as few evergreen broadleaf plants can tolerate severe cold below about -25°C.

In areas where there is a reason for being deciduous (i.e. a cold season or dry season), being evergreen is usually an adaptation to low nutrient levels. Deciduous trees lose nutrients whenever they lose their leaves, and they must replenish these nutrients from the soil to build new leaves.

When few nutrients are available, evergreen plants have an advantage, even though their leaves and needles must be able to withstand cold and/or drought, and are thus less efficient at photosynthesis. In warmer areas, species such as some pines and cypresses grow on poor soils and disturbed ground.

In Rhododendron, a genus with many broadleaf evergreens, several species grow in mature forests but are usually found on highly acidic soil where the nutrients are less available to plants. In taiga or boreal forests, it is too cold for the organic matter in the soil to decay rapidly, so the nutrients in the soil are less easily available to plants, thus favouring evergreens.

In temperate climates, evergreens can reinforce their own survival; evergreen leaf and needle litter has a higher carbon-nitrogen ratio than deciduous leaf litter, contributing to a higher soil acidity and lower soil nitrogen content.

These conditions favour the growth of more evergreens and make it more difficult for deciduous plants to persist. In addition, the shelter provided by existing evergreen plants can make it easier for other evergreen plants to survive cold and/or drought.

Deserts have a reputation for supporting very little life. Compared to wetter regions this may be true, although

deserts often have high biodiversity, including animals that remain hidden (especially during the daylight) to preserve moisture. About one-fifth of Earth's land surface is desert.

Desert landscapes have certain features. Deserts are often composed of sand and rocky surfaces. Sand dunes called ergs and stony surfaces called Reg or hamada surfaces compose a minority of desert surfaces. Exposures of rocky terrain are typical, and reflect minimal soil development and sparseness of vegetation. Bottom lands may be salt-covered flats.

Eolian (wind-driven) processes are major factors in shaping desert landscapes. Cold deserts have similar features but the main form of precipation is snow rather than rain. The largest cold desert is Antarctica (composed of about 98 percent thick continental ice sheet and 2 percent barren rock). The largest hot desert is the Sahara.

Deserts sometimes contain valuable mineral deposits that were formed in the arid environment or that were exposed by erosion. Because deserts are dry, they are ideal places for human artifacts and fossils to be preserved.

Deserts usually have an extreme temperature range. Most deserts have a low temperature at night. This is because the air is very dry (contains little moisture) and therefore holds little heat so as soon as the sun sets, the desert cools quickly. Also, cloudless skies increase the release of heat at night.

In the Köppen climate classification system, deserts are classed as (BW).

Most classifications rely on some combination of the number of days of rainfall, the total amount of annual rainfall, temperature, humidity, or other factors. In 1953, Peveril Meigs divided desert regions on Earth into three categories according to the amount of precipitation they received.

In this now widely accepted system, extremely arid lands have at least 12 consecutive months without rainfall, arid lands have less than 250 millimeters of annual rainfall, and semiarid lands have a mean annual precipitation of between 250 and 500 millimeters. Arid and extremely arid land are deserts, and semiarid grasslands generally are referred to as steppes.

However, lack of rainfall alone can't provide an accurate description of what a desert is. For example, Phoenix, Arizona receives less than 250 millimeters (10 inches) of precipitation per year, and is immediately recognized as being located in a desert. The North Slope of Alaska's Brooks Range also receives less than 250 millimeters of precipitation per year, but is not generally recognized as a desert region.

The difference lies in something termed "potential evapotranspiration." The water budget of an area can be calculated using the formula P-PE+/-S, wherein P is precipitation, PE is potential evapotranspiration rates and S is amount of surface storage of water.

Evapotranspiration is the combination of water loss through atmospheric evaporation, coupled with the evaporative loss of water through the life processes of plants. Potential evapotranspiration, then, is the amount of water that could evaporate in any given region. Tucson, Arizona receives about 300 millimeters, (12 inches), of rain per year, however about 2500 millimeters, (100 inches), of water could evaporate over the course of a year.

In other words, about 8 times more water could evaporate from the region than actually falls. Rates of evapotranspiration in other regions such as Alaska are much lower, so while these regions receive minimal precipitation, they should be designated as specifically different from the simple definition of a desert: a place where evaporation exceeds precipitation.

That said, there are different forms of deserts. Cold deserts can be covered in snow; such locations don't receive much precipitation, and what does fall remains frozen as snow pack; these are more commonly referred to as tundra if a short season of above-freezing temperatures is experienced, or as an ice cap if the temperature remains below freezing year-round, rendering the land almost completely lifeless.

Most non-polar deserts are hot because they have little water. Water tends to have a cooling, or at least a moderating, effect in environments where it is plentiful. In some parts of the world deserts are created by a rain shadow effect in which air masses lose much of their moisture as they move over a mountain range; other areas are arid by virtue of being very far from the nearest available sources of moisture (this is true in some middle-latitude landmass interior locations, particularly in Asia).

Deserts are also classified by their geographical location and dominant weather pattern as trade wind, mid-latitude, rain shadow, coastal, monsoon, or polar deserts. Former desert areas presently in non-arid environments are paleodeserts, and extraterrestrial deserts exist on other planets.

Montane deserts

Montane deserts are arid places with a very high altitude; the most prominent example is found north of the Himalaya, in parts of the Kunlun Mountains and the Tibetan Plateau. Many locations within this category have elevations exceeding 3,000 meters (9,843 feet) and the thermal regime can be hemiboreal.

These places owe their profound aridity (the average annual precipitation is often less than 40mm) to being very far from the nearest available sources of moisture.

Iguanas tend to have tall, flat plates jutting from their back like spines, when adult. Several species of this genus are

common as pets, especially the Green Iguana in the United States and Canada, which can easily grow to six feet long, even in captivity.

When treated well they can be docile, affectionate, litterbox trainable, and even walked on a leash. Such pets are either crèche-raised, or harvested from the wild in Mexico. The average life span of a well taken care of pet

iguana is usually 20 years. Captured iguanas kept as pets tend to be thin and nervous, often dying from side-effects of the stress of adapting to captivity - though if they're given a large swimming area in which to hide, their chances of survival improve, as they live on streambanks in the wild, diving in when alarmed or for other reasons.

As they are cold-blooded creatures, they thrive in humid climates. The Green Iguana needs to be in temperatures of 75 to 90 degrees. If it is not kept under UVB lighting it can develop metabolic bone disease.

Iguanas can be considered as an invasive species, along the gulf coast of Florida, especially on Gasparilla Island (where there is an estimated population of over 12000). They commonly hide in the attics of houses, destroy gardens, and burrow in beaches. As an introduced species, they contribute to natural habitat loss, spread salmonella, and could be responsible for the recent decline of the gopher tortoise.

An old synonym for snake is serpent (which comes from Old French, and ultimately from PIE *serp-, "to creep"); in modern usage this usually refers to a mythic or symbolic snake, and information about such creatures will be found under serpent (symbolism). This article deals with the biology of snakes.

The phylogeny of snakes is poorly known due to the fact that snake skeletons

are typically small and fragile, making fossilization unlikely. It has however been generally agreed, on the basis of morphology, that snakes descended from lizard-like ancestors. Recent research based on genetics and biochemistry confirms this; snakes form a venom clade with several extant lizard families.

Recent fossil evidence suggests that snakes directly evolved from burrowing lizards, either varanids or some other group. An early fossil snake, Najash rionegrina, was a two-legged burrowing animal with a sacrum, fully terrestrial. One extant analog of these putative ancestors is the earless monitor Lanthanotus of Borneo, although it also is semi-aquatic. As these ancestors became more subterranean, they lost their limbs and became more streamlined for burrowing.

Features such as the transparent, fused eyelids and loss of external ears, according to this hypothesis, evolved to combat subterranean conditions (scratched corneas, dirt in the ears). According to this hypothesis, snakes re-emerged onto the surface of the land much as they are today. Other primitive snakes are known to have possessed hindlimbs but lacked a direct connection of the pelvic bones to the vertebrae, including Haasiophis, Pachyrhachis and Eupodophis) which are slightly older than Najash.

Modern boas do have vestigal hind limbs, tiny, clawed digits known as anal spurs and used to grasp during mating.

The alternative hypothesis, based on morphology, suggests that ancestors were related to mosasaurs — extinct aquatic reptiles from the Cretaceous — which in turn are thought to have derived from varanid lizards. Under this hypothesis, the fused, transparent eyelids of snakes are thought to have evolved to combat marine conditions (corneal water loss through osmosis), while the external ears were lost through disuse in an aquatic environment, ultimately leading to an animal similar in appearance to sea snakes of today.

In the Late Cretaceous, snakes re-colonized the land much like they are today. Fossil snake remains are known from early Late Cretateous marine sediments, which is consistent with this hypothesis, particularly as they are older than the terrestrial Najash rionegrina. Similar skull structure; reduced/absent limbs; and other anatomical features found in both mosasaurs and snakes lead to a positive cladistical correlation, though some features are also shared with varanids.

Supposedly similar locomotion for both groups is also used as support for this hypothesis. Genetic studies have indicated that snakes are not especially related to monitor lizards, and (it has been claimed) therefore not to mosasaurs, the proposed ancestor in the aquatic scenario of their evolution. However, there is more evidence linking mosasaurs to snakes than to varanids. Fragmentary remains that have been found from the Jurassic and Early Cretaceous indicate deeper fossil records for these groups, which may eventually refute either hypothesis.

The great diversity of modern snakes appeared in the Paleocene, probably correlated with the adaptive radiation of mammals following the extinction of the dinosaurs.

All snakes are carnivorous, eating small animals including lizards and other snakes, rodents and other small mammals, birds, eggs or insects. Some snakes have a venomous bite which they use to kill their prey before eating it. Other snakes kill their prey by constriction. Still others swallow their prey whole and alive.

Snakes do not chew their food and have a very flexible lower jaw, the two halves of which are not rigidly attached, and numerous other joints in their skull (see snake skull), allowing them to open their mouths wide enough to swallow their prey whole, even if it is larger in diameter than the snake itself. It is a common misconception that snakes actually dislocate their lower jaw to consume large prey.

After eating, snakes become torpid while the process of digestion takes place. Digestion is an intensive activity, especially after the consumption of very large prey. In species which feed only sporadically, the entire intestine enters a reduced state between meals to conserve energy, and the digestive system is 'up-regulated' to full capacity within 48 hours of prey consumption.

So much metabolic energy is involved in digestion that in Crotalus durissus, the Mexican rattlesnake, an increase of body temperature to as much as 14 degrees Celsius above the surrounding environment has been observed. Because of this, a snake disturbed after having eaten recently will often regurgitate the prey in order to be able to escape the perceived threat.

However, when undisturbed, the digestive process is highly efficient, dissolving and absorbing everything but hair and claws, which are excreted along with uric acid waste. Snakes have been known to occasionally die from trying to swallow an animal that is too big. Snake digestive acids are unable to digest most plant matter, which passes through the digestive system mostly untouched.

Snakes do not normally prey on people, but there are instances of small children being eaten by large constrictors in the jungle. While some particularly aggressive species exist, most will not attack humans unless startled or injured, preferring instead to avoid contact. In fact, the majority of snakes are either non-venomous or possess venom that is not harmful to humans.

Skin

The skin is covered in scales. Most snakes use specialized belly scales to move, gripping surfaces. The body scales may be smooth, keeled, or granular. Their eyelids are transparent "spectacle" scales which remain permanently closed. They shed their skin periodically. Unlike other reptiles, this is done in one piece, like pulling off a sock. It is thought that the primary purpose of this is to remove external parasites.

This periodic renewal has led to the snake being a symbol of healing and medicine, as pictured in the Rod of Asclepius. In "advanced" (Caenophidian) snakes, the broad belly scales and rows of dorsal scales correspond to the vertebrae, allowing scientists to count the vertebrae without dissection.

If there is not enough humidity in the air while snakes are shedding their skin, it can be very dangerous for the snake, because the dry skin does not shed. Skin that remains attached to the snake can harbour diseases and parasites. A tail tip that is not removed can constrict as the snake grows, cutting off the blood supply to the end of the tail causing it to drop off. A retained spectacle can cause the snake to become blind in the affected eye.

Perception

While snake vision is unremarkable (generally being best in arboreal species and worst in burrowing species), it is able to detect movement. Some snakes, like the Asian vine snake, have binocular vision. In most snakes, the lens moves back and forth within the eyeball to focus. In addition to their eyes, some snakes (pit vipers, pythons, and some boas) have infrared-sensitive receptors in deep grooves between the nostril and eye which allow them to "see" the radiated heat.

Snakes have no external ears, but they do have a bone called the quadrate under the skin on either side of the head which focuses sound into the cochlea.[1] Their sense of hearing is most sensitive to frequencies around 200–300 Hz.

A snake smells by using its forked tongue to collect airborne particles then passing them to the Jacobson's organ in the mouth for examination. The fork in the tongue gives the snake a sort of directional sense of smell. The part of the body which is direct contact with the surface of the ground is very sensitive to vibration thus a snake able to sense a person approaching.

Internal organs

The left lung is very small or sometimes even absent, as snakes' tubular bodies require all of their organs to be long and thin, and to accommodate them all only one lung is functional. This lung contains a vascularized anterior portion and a posterior portion which does not function in gas exchange. This 'saccular lung' may be used to adjust buoyancy in some aquatic snakes and its function remains unknown in terrestrial species.

Also, many organs that are paired, such as kidneys or reproductive organs, are staggered within the body, with one located ahead of the other. The most primitive snakes, including boas and pythons, have anal spurs, a pair of claws on either side of the cloaca which are used by the males for stimulation of females during mating.

Locomotion

Snakes utilize a variety of methods of movement which allows them substantial mobility in spite of their legless condition. All snakes are capable of lateral undulation, in which the body is flexed side-to-side, and the flexed areas propagate posteriorly, giving the overall shape of a posteriorly propagating sine wave. In addition, all snakes are capable of concertina movement.

This method of movement can be used to both climb trees and move through small tunnels. In the case of trees, the branch is grasped by the posterior portion of the body, while the anterior portion is extended. The anterior portion then grasps the branch, and the posterior portion is pulled forward. In the case of tunnels, instead of grasping, the body loops are pressed against the tunnel walls to attain traction, but the motion is otherwise similar.

Another common method of locomotion is rectilinear locomotion, in which the snake remains straight and propels itself via a caterpillar-like motion of its belly-muscles. This mode is usually only used by very large, heavy snakes, such as large pythons and vipers. The most complex and interesting mode is sidewinding, an undulatory motion used to move across slippery mud or loose sand.

Not all snakes dwell on land; sea snakes live in shallow tropical seas.

Studies of the motion and muscle activity of moving snakes have shed light on how each of these modes is achieved.

In terrestrial lateral undulation, posteriorly propagating unilateral waves of muscle contraction occur. The regions of muscle activity for each side extend from the most concave point on that side posteriorly to the most convex side. Thus, when a point on the snake's body is maximally flexed to the right, the right muscles activate, bending it back to the left until it's maximally right-convex, at which point the right side muscles turn off, and the left side muscles turn on.

Speed is modulated primarily by alteration of frequency. Aquatic lateral undulation appears superficially similar, but the muscle activation pattern is different, with the regions of muscle activity being 'shifted' posteriorly to where they would be in terrestrial lateral undulation. The reasons for this difference are not fully understood.

Sidewinding, though it appears complex and confusing, is actually a simple modification of terrestrial lateral undulation. At the points of maximal flexion, the dorsalmost muscle group (traversospinalis group) activates, lifting that portion of the body over the ground, and resulting in other portions of the body remaining in static contact.

This mode is used to cross slick surfaces such as mud flats and sand, and has nothing to do with thermoregulation, as is sometimes erroneously stated. Many species of snake, including species commonly kept as pets and which do not usually encounter deserts or mud flats, will sidewind when placed on a slick floor or tabletop and enticed to move fast.

Concertina locomotion and rectilinear locomotion are less well understood. Studies of muscle activity have only been done for tunnel concertina locomotion, which shows that the muscles are unilaterally active in static regions of bending in order to brace the snake against the tunnel walls.

Rectilinear is believed to rely on different muscles from the other modes; while they all rely on the large epaxial muscles, rectilinear locomotion seems to rely upon the small costocutaneous muscles. However, this has not been verified experimentally, due to the difficulties in working with these small muscles.

"Flying" snakes

Several species of snake have the ability to glide, all being in the genus Chrysopelea. They are quite capable at it, able to travel as far as 137 metres through the air. They tend to make slithering motions to steer and help propel themselves along, propulsion being something unusual among the many gliding animals.

Reproduction

A wide range of reproductive modes are used by snakes. All snakes employ internal fertilization, accomplished by means of paired, forked hemipenes, which are stored inverted in the male's tail. Most snakes lay eggs, and of those most species abandon them shortly after laying; however, some species are ovoviviparous and retain the eggs within their bodies until they are almost ready to hatch.

Recently, it has been confirmed that several species of snake are fully viviparous, nourishing their young through a placenta as well as a yolk sac, highly unusual among reptiles, or indeed anything else outside of placental mammals. Retention of eggs and live birth are commonly, but not exclusively, associated with cold environments, as the retention of the young within the female allows her to control their temperature more effectively than if the developing young were in external eggs.

Snake bites

Documented deaths resulting from snake bites are uncommon in most areas of the world. Only about 450 species of snakes are venomous (with only about 250 that are able to kill a human), and among the 7,000 Americans bitten by venomous snakes every year, fewer than fifteen die (lightning kills more). See snakebites for more information, including prevention of snake bites and first aid treatment.

Venomous Snakes

While about a quarter of snakes are venomous, not all such species are dangerous to humans. See snake venom. The following groups of snakes can be aggressive and inflict dangerous, even potentially lethal bites. This list is incomplete.

Adder

Asp

Black snake

Black mamba

Boomslang

Brown snake (Australian)

Bushmaster

Cobra

Common lancehead

Coral snake

Cottonmouth

American Copperhead

Australian Copperhead

Death adder

Diamondback

Fer-de-lance

Fierce Snake

Gaboon Viper

King Cobra

Krait

Lancehead

Mamba

Philippine Cobra

Philippine Spitting Cobra

Pit Viper

Rattlesnake

Russell's Viper

Saw-scaled Viper

Sea snake

Taipan

Tiger snake

Urutu

The first turtles are believed to have existed in the Mesozoic, around 200 million years ago. Their exact ancestry is disputed. It was believed that they are the only surviving branch of the ancient clade Anapsida, which includes groups such as procolophonoids, millerettids, protorothyrids and pareiasaurs.

All anapsid skulls lack a temporal opening, while all other

extant amniotes have temporal openings (although in mammals the hole has become the zygomatic arch). Most anapsids became extinct in the late Permian period, except procolophonoids and possibly the precursors of the testudines (turtles).

However, it was recently suggested that the anapsid-like turtle skull may be due to reversion rather than to anapsid descent. More recent phylogenetic studies with this in mind placed turtles firmly within diapsids, slightly closer to

Squamata than to Archosauria. All molecular studies have strongly upheld this new phylogeny, though some place turtles closer to Archosauria. Re-analysis of prior phylogenies suggests that they classified turtles as anapsids both because they assumed this classification (most of them studying what sort of anapsid turtles are) and because they did not sample fossil and extant taxa broadly enough for constructing the cladogram. While the issue is far from resolved, most scientists now lean towards a diapsid origin for turtles.

Physical Description

Turtles vary widely in size, although marine turtles tend to be relatively big animals. The largest chelonian is a marine turtle, the great leatherback sea turtle, which can reach a shell length of 200 cm (72 in) and can reach a weight of over 750 kg (2,000 lb). Freshwater turtles are smaller, with the largest species being the Asian softshell turtle Pelochelys cantorii, which has been reported to measure up to 200 cm or 80 inches (Das, 1991).

This dwarfs even the better-known alligator snapping turtle, the largest chelonian in North America, which attains a shell length of up to 80 cm (31.5 in) and a weight of about 76 kg (170 lb). Giant tortoises of the genera Geochelone, Meiolania, and others were relatively widely distributed around the world into prehistoric times, and are known to have existed in North and South America, Australia, and Africa.

They became extinct at the same time as the appearance of Man, and it is assumed that humans hunted them for food. The only surviving giant tortoises are on the Seychelles and Galápagos Islands and can grow to over 130 cm (50 in) in length, and weigh about 300 kg (670 lb).

The largest ever chelonian was Archelon ischyros, a Late Cretaceous sea turtle known to have been up to 4.6 m (15 ft) long [3].

The smallest turtle is the speckled padloper tortoise of South Africa. It measures no more than 8 cm (3 in) in length and weighs about 140 g (5 oz). Two other species of small turtles are the American mud turtles and musk turtles that live in an area that ranges from Canada to South America. The shell length of many species in this group is less than 13 cm (5 in) in length.

Shell

The upper shell of the turtle is called the carapace. The lower shell that incases the belly is called the plastron. The carapace and plastron are joined together on the turtle's sides by bony structures called bridges. The inner layer of a turtle's shell is made up of about 60 bones that includes portions of the backbone and the ribs, meaning the turtle can not crawl out of its shell.

In most turtles, the outer layer of the shell is covered by horny scales called scutes that are part of its outer skin, or epidermis. Scutes are made up of a fiberous protein called keratin that also makes up the scales of other reptiles. These scutes overlap the seams between the shell bones and add strength to the shell. Some turtles do not have horny scutes. For example, the leatherback sea turtle and the soft-shelled turtles have shells covered with leathery skin instead.

The shape of the shell gives helpful clues to how the turtle lives. Most tortoises have a large domed-shaped shell that makes it difficult for predators to crush them between their jaws. One of the few exceptions is the African pancake tortoise which has a flat, flexible shell that allows it to hide in rock crevices. Most aquatic turtles have flat, streamlined shells that aid with swimming and diving. American snapping turtles and musk turtles have small, cross-shaped plastrons that give the turtle more efficient leg movement for walking along the bottom of ponds and streams.

Tortoises have rather heavy shells in constrast to aquatic and soft-shelled turtles that have lighter shells that help them avoid sinking in the water and swim faster and more agile. These light shells have large spaces called fontanelles between the shell bones. The shell of a leatherback turtle is extremely light because they lack scutes and contain many fontanelles.

The color of a turtle's shell may vary. Shells are commonly coloured brown, black, or olive green. In some species, shells may have red, orange, yellow, or grey markings and these markings are often spots, lines, or irregular blotches. One of the most colorful turtles is the eastern painted turtle which includes a yellow plastron and a black or olive shell with red markings around the rim.

Skin and Moulting

As mentioned above, the outer layer of the shell is part of the skin, each scute (or plate) on the shell corresponding to a single modified scale. The remainder of the skin is composed of skin with much smaller scales, similar to the skin of other reptiles. Turtles and terrapins do not moult their skins all in one go, as snakes do, but continuously, in small pieces.

When kept in aquaria, small sheets of dead skin can be seen in the water, having been sloughed off, often when the animal deliberately rubs itself against a piece of wood or stone. Tortoises also shed skin, but a lot of dead skin is allowed to accumulate into thick knobs and plates that provide protection to parts of the body outside the shell.

The scutes on the shell are never moulted, and as they accumulate over time, the shell becomes thicker. By counting the rings formed by the stack of smaller, older scutes on top of the larger, newer ones, it is possible to estimate the age of a turtle, if you know how many scutes are produce in a year. This method is not very accurate, partly because growth rate is not constant, but also because some of the scutes on the shell eventually fall away from the shell.

Head

Most turtles and tortoises have eyes placed on the upper sides of their heads. Species of turtles that spend most of their life on land have their eyes looking down at objects in front of them. Some aquatic turtles, such as snapping turtles and soft-shelled turtles, have eyes closer to the top of the head.

These species of turtles can hide from predators in shallow water where they lie entirely submerged except for their eyes and nostrils. Sea turtles possess glands near their eyes that produce salty tears that rids their body of excess salt taken in from the water they drink.

Turtles use their jaws to cut and chew food. Instead of teeth, the upper and lower jaws of the turtle are covered by horny ridges. Carnivorous turtles usually have knife-sharp ridges for slicing through their prey. Herbivourous turtles have serrated edged ridges that help them cut through tough plants. Turtles use their tongues to swallow food, but they can't, unlike most reptiles, stick out their tongues to catch food.

Limbs

The fully terrestrial tortoises have short, sturdy feet. Tortoises are famous for moving slowly, in part because of their heavy shell but also because of the relatively inefficient sprawling gait that they have, with the legs being bent, as with lizards rather than being straight and directly under the body, as is the case with mammals.

The amphibious terrapins normally have limbs similar to those of tortoises except that the feet are webbed and often have long claws. These terrapins swim using all four feet in a way similar to the doggy paddle, with the feet on the left and right side of the body alternately providing thrust.

Large terrapins tend to swim less than smaller ones, and the very big species, such as aligator snapping turtles, hardly swim at all, preferring to simply walk along the bottom of the river or lake. As well as webbed feet, terrapins also have very long claws, used to help them clamber onto riverbanks and floating logs, upon which they like to bask.

Male terrapins tend to have particularly long claws, and these appear to be used to stimulate the female while mating. While most terrapins have webbed feet, a few terrapins, such as the pig-nose turtles, have true flippers, with the digits being fused into paddles and the claws being relatively small. These species swim in the same way as sea turtles (see below).

Sea turtles are entirely aquatic and instead of feet they have flippers. Sea turtles "fly" through the water, using the an up-and-down motion of the front flippers to generate thrust; the back feet are not used for propulsion but may be used as rudders for steering.

Compared with terrapins, sea turtles have very limited mobility on land, and apart from the dash from the nest to the sea as hatchlings, male sea turtles normally never leave the sea. Females must come back onto land to lay eggs. They move very slowly and laboriously, dragging themselves forwards with their flippers. The back flippers are used to dig the burrow and then fill it back with sand once the eggs have been deposited.

Kangaroo rats, genus Dipodomys, are small rodents native to North and Central America.

The name derives from their bipedal form (they hop like tiny kangaroos) but the resemblance is purely visual: kangaroo rats and kangaroos are only distantly related, as

both are mammals.

Twenty two species are currently recognized. Size varies from 100 to 200 mm, with a tail of equal or slightly greater length; weight can be anywhere between 35 and 180 grams. The most distinctive feature of the kangaroo rats is their very long hind legs. Like the jerboas of African and Asian deserts and the hopping mice of outback Australia, kangaroo rats have highly developed

hind legs, live in deep burrows which shelter them from the worst of the desert heat, and rarely drink water. Instead, they have a highly water-efficient metabolisim (their kidneys are at least four times more efficient than those of humans), and manufacture water by chemical breakdown of their food.

Despite sharing so many characteristics with jerboas and hopping mice, the three groups are not closely related to one another: the similarities are the result of convergent evolution.

Kangaroo rats are found in arid and semi-arid areas of the United States and Mexico which retain some grass or other vegetation. Their diet includes seeds, leaves, stems, buds, some fruit, and insects. Most kangaroo rat species use their burrows and buried caches nearby to store food against the possibility of bad seasons.

The Banner-tailed Kangaroo Rat has been recorded making burrows with several storage chambers up to 25 cm in diameter each, and containing almost 6 kilograms of stored food.

Unlike the jerboas and hopping mice, but like their close relatives the pocket mice, kangaroo rats have large cheek pouches that open on either side of the mouth and extend back to the shoulders.

They fill the pouches with food or nesting material ready for transport back to the burrow, then empty them by turning them inside out, like pockets, with their forepaws. There is a special muscle that, once the pouch is empty and clean, pulls it back in again.

The overall colour of the kangaroo rats can be anywhere between pale sandy yellow and dark brown, with a white underside and often with white banding across the thighs. Tails tend to be dark with white sides and a tuft of longer hairs. Facial markings vary from one species to another, but all have an oil gland between the shoulders.

Cactus is the name given to any member of the flowering plant family Cactaceae. Cacti are almost exclusively New World plants. This means that they are native only in North America, South America, and the West Indies.

There is however one exception, Rhipsalis baccifera; this species has a pantropical distribution, occurring in the Old World in tropical Africa, Madagascar and Sri Lanka as well as in tropical America.

This plant is thought to be a relatively recent colonist in the Old World (within the last few thousand years), probably carried as seeds in the digestive tracts of migratory birds. Many other cacti have become naturalized to similar environments in other parts of the world after being introduced by people.

Many succulent plants in both the Old and New World bear a striking resemblance to cacti, and are often called "cactus" in common usage.

This is, however, due to parallel evolution; none of these are closely related to the Cactaceae. One distinct

identifying characteristic of the Cactus family is the areole, a specialized structure from which spines and new shoots grow.

Cacti are believed to have evolved in the last 30 to 40 million years. Long ago, the Americas were joined to the other continents, but separated due to continental drift. Unique species in the New World must have developed after the continents had moved apart. Significant distance between the continents was only achieved around in the last 50 million years. This may explain why cacti are so rare in Africa; the continents had already separated when cacti evolved.

Like other succulents, cacti are well-adapted to life with little precipitation. The leaves have evolved into spines, which in addition to allowing less water to evaporate through transpiration than regular leaves, defend the cactus against water-seeking animals. Photosynthesis is carried out by enlarged stems, which also store water.

Unlike many other succulents, the stem is the only part of a true cactus where this takes place. Very few members of the family have leaves, and when present these are usually rudimentary and soon fall off; they are typically awl-shaped and only 1-3 mm long.

Two genera, Pereskia and Pereskiopsis, do however retain large, non-succulent leaves 5-25 cm long, and also non-succulent stems. Pereskia has now been determined to be the ancestral genus from which all other cacti evolved.

Cacti come in a wide range of shapes and sizes. Some grow to great size. Some cacti produce beautiful flowers, which like spines and branches arise from areoles. Many cactus species are night-blooming, as they are pollinated by nocturnal insects or small animals, principally moths and bats. Cacti range from small and round to pole-like and tall, such as the Saguaro.

A number of cactus species are cultivated for use as houseplants, as well as for ornamental gardens. They often form part of xerophilic (dry) gardens in arid regions. Some cacti bear edible fruit.

In physical geography, a steppe, pronounced in English as step, is a plain without trees (apart from those near rivers and lakes); it is similar to a prairie, although a prairie is generally considered as being dominated by tall grasses, while short grasses are said to be the normal in the steppe.

It may be semi-desert, or covered with grass or shrubs, or both depending on the season and latitude .

The term is also used to denote the climate encountered in regions too dry to support a forest, but not dry enough to be a desert.

They are usually found in areas of the world less prone to moisture. The soil is considered too moist to be a desert,

but too dry to support normal forest life. The climate of steppes can be summarized by hot summers and cold winters, averaging 250-500

mm (10-20 inches) of rain per year. Plant life is usually greater than one foot tall, including the blue grama and buffalo grass, cacti, sagebrush, speargrass, and other small relatives of the sunflower.

Animal life includes but isn't limited to the Corsac Fox, Mongolian Gerbil, Saiga Antelope, Northern Lynx, and the Saker Falcon.

The world's largest zone of steppes, which is often referred to as "the Great Steppe", is found in central Russia and neighbouring countries in Central Asia. The Pontic steppe stretches from the Ukraine in the west to the Ural Mountains and the Caspian Sea.

To the east of the Caspian Sea, the steppes extend through Turkmenistan, Uzbekistan and Kazakhstan to the Altai, Koppet Dag and Tian Shan ranges. To the north, on the eastern side of the Urals, is the forested West Siberian Plain taiga, extending nearly as far as the Arctic Ocean.

Another large steppe area is located in the central United States and western Canada. The High Plains steppe is the westernmost part of the Great Plains region.

Plants

Fringed Sagebrush

Common Names: Sagebrush, prairie sagewort, fringed wormwood, arctic sagebrush

Genus: Artemisia

Species: frigida

Fringed sagebrush is a woody shrub with silvery leaves and little yellow flowers.

Sagebrush has a strong odor after it rains that smells like turpentine or camphor.

Fringed sagebrush is a low, mat-forming shrub. It gets to be 4 to 16 inches (10-40 cm) in height and rarely grows taller than 24 inches (60 cm). Soft stems grow from a woody base. It has many little leaves that grow from the stem and are finely cut. The leaves have a gray or silvery look to them. Flowers are yellow and very small.

Fringed sagebrush has a unique root system. It adapts to the conditions that it finds itself living in. It grows deep taproots where the water level is low, and lots of surface roots when the water is easy to get at.

The adaptable root systems allows fringed sagebrush to to survive drought periods which commonly occur in the Great Plains and the Mongolian steppe.

The sagebrush is used for livestock because it is so high in protein. Many wildlife species like to eat it during spring, fall, and winter but not during the summer. Many bird species use the sagebrush Artemesia tridentata for making nests. Artemisia tridentata is also used for fuel in places where other burnable woody plants can't be grown.

Fringed sagebrush can live in many places, but not in alkaline soil. It grows on dry open sites in the foothills, mountains, and plains from Mexico northward to Canada and Alaska, and into Eurasia.

Fringed sagebrush grows especially in the high, cold plains of the United States, Canada, and Mongolia. This makes Sagebrush a steppe plant because it can grows in dry and cold climates.

Milk Vetch

Common Name:Great Wall Astragalus, or Sha Da Wang (flower that grows in desert)

Genus: Astragalus

Species: adsurgens

Parts Used: the whole plant

Milkvetch is a perennial found throughout northern and southwestern China and northern North America. It is a perfect plant for cold, and arid to semi-arid regions with poor or saline soils. It has a very long tap root and can get water deep in the ground. In China it is grown as fodder, green manure and for soil conservation. Milk vetches are part of the bean family (Fabaceae). In Latin, fab means "bean".

Each plant has a couple of stems that can grow to be 1.5 to 2 m tall. The leaves are each composed of 9 to 19 narrow leaflets, and are about 2 to 4 inches long with soft hair all over them. The main tap root is thick and has many roots growing off it. A secondary root system starts about 20

cm. under the ground and can reach out to about 150 cm in diameter. Nodules develop on the roots closer to the surface from which new plants grow.

Milkvetch flowers thoughout August. The lavender or bluish-purple flowers are about 1/2 inch long and arranged in a dense cluster. The cluster grows on a short stalk and can be cylindrical and about 3 inches long.

Seeds grow in a small, hairy pods that turn black. The seeds are small and black and sometimes rattle in the pod, giving some species of this plant the name Rattle Pod.

One species of Astragalus, Astragalus lentiginosus, contain the alkaloid swainsonine, which can cause locoism. When animals eat this astragalus their nervous systems become impaired, and they become very excited when disturbed. Sometimes they died. In the old days it used to be known as "loco weed".

A less deadly variety of vetch can be found growing along our country's highways as soil erosion control. In the spring the blue flowers of vetch will carpet the sides of roads from New Enland to California.

Sweet Vernal

Common Names: Pheasant's Eye, False Hellebore

Genus: Adonis

Species: vernalis

Parts Used: extract from the flowers

Sweet Vernal is a perennial which grows from south-east Sweden to the south of Europe and eastwards to western Siberia. It is a typical steppe plant, and it doesn't grow in too many places in Europe.

Because of loss of habitat and too much of it has been collected for medical purposes, Sweet Vernal is becoming scarce there. More of it is starting to grow in eastern Europe.

This is a very special plant because it is a potent heart medicine. The plant contains something called glycoside Adonidin, which is used in remedies for chronic heart problems and as a tranquilizer.

It works almost exactly like digitalin, which comes from Foxgloves, but is stronger and doesn't build up in the body. It is used especially in cases where people are also suffering from kidney disease, as well as heart problems. It does

produce vomiting and diarrhea, however and is only used when digitalis fails.

Because Sweet Vernal can't be cultivated, plants have to be collected from the wild, which make them very vulnerable. A rare plant in most of its range, it has legal protection from gathering in most countries.

Sweet Vernal is a very beautiful flower. It blooms in early spring and has a rich, golden, buttercup-like glow. Its leaves are like filigree, and very delicate. Adonis vernalis is part of the Ranunculaceae family.

Rhubarb

Genus: Rheum

Species: rhabarbarum

Parts Used: the roots and the stems

Rhubarb is a member of the sorrel family, and grows in the wild in western and northwestern provinces of China. It is grown commercially in much of Europe and the United States. The name rhubarb comes from the Medieval Latin reubarbarum, literally meaning barbarian rhubarb.

It is part of the Asian buckwheat family. Rhubarb originally came from the steppes of Asia over 2000 years ago. There it was used as medicine. Its roots were ground up and used as a purgative, or an old version of ex-lax. Rhubarb didn't give people the stomach cramps of other purgatives and soon became a favorite in western countries as well.

Rhubarb is a perennial plant with large fleshy roots and large leaves with long, thick stems. The plant grows to be about 2 to 3 feet under cultivation, but doesn't grow over 1 foot in the wild. It likes climates where the spring is wet and cool.

The stems are harvested in the early spring. Only the stems of rhubarb are

used in cooking because the leaves are very poisonous. It is used by many to make deserts, like strawberry-rhubarb pie. The different colors of the plant's stem can range from green to pink to rose to ruby red. The darker red stalks have a milder, sweeter flavor than the green. Rhubarb is very rich in vitamin C and dietary fibers.

Tumbleweed

Common Name: Russian Thistle

Genus: Salsola

Species: collina

When westerns were big in the movies, you could always hear some lonesome cowboy sing about the tumbling tumbleweed. The tumbleweed stood for everything a cowboy was; a little ugly, lanky, and a foot loose rambler. Deserted ghost towns would have tumbleweeds rolling down main street.

Would you believe that tumbleweed actually hitched a ride from the steppes of Mongolia with a shipment of grain? That's how it got here, and it isn't a native plant at all. Very strange, but true.

Tumbleweed is also known as Russian thistle, and is a member of the Goosefoot family. It is a round, bushy, much-branched plant growing 1 to 3-1/2 feet high. The branches are slender, and soft when young, woody when mature. The leaves are alternate. The first ones start off being dark green, soft, slender, and 1 to 2-1/2 inches long.

These drop off and the next set of leaves are short, stiff, spiny, and not over 1/2 inch long. The flowers are small, green-white or pink in color. Seeds are about 1/16 inch in diameter and shaped like a cone.

Tumbleweed grows on dry plains, in cultivated fields, roadsides, and waste places, mainly in grain-growing areas. It has a special way of broadcasting its seeds. It doesn't depend on the wind, or birds. It doesn't hitchhike on the fur of animals.

When it becomes mature, it breaks off at the base and because it is shaped like a ball, it tumbles before the wind, scattering seeds where ever it goes. It is all over Colorado up to 8,500 feet.

Armadillos are many of several small placental mammals of the family Dasypodidae, mostly known for having a bony armor shell. Their average size is about 75 centimeters (30 inches), including tail.

All species are native to the American continents, where they inhabit a variety of environments. In the United States, the sole resident armadillo is the 9-banded armadillo (Dasypus novemcinctus), which is most common

in the central southern states, particularly Texas.

Dasypodidae is the only family in the order Cingulata. Until as recently as 1995 the family was placed in the order Xenarthra, along with the anteaters and sloths. There are several species of armadillo, some of which are distinguished by how many bands they have on their armor. The nine-banded form can not roll

itself into a ball. They mainly run away or burrow from predators.

Corsac Fox

Common Names: Cosac Fox, Steppe Fox

Genus:Vulpes

Species: corsac

The Corsac fox is a long legged, reddish gray fox with large ears and a short, pointy face. Its coat is grayish-red with silver undertones, and the under parts are white with yellow undertones. Its chin is also white. They have small teeth compared to other foxes. The Corsac Fox is slightly smaller than the red fox, about 50-60 cm, and as tall as an average sized dog.

Corsac foxes like to live in burrows on steppes and semi-deserts, and are originally from the steppes of Mongolia. You would not find them in areas that are used for agriculture. They are omnivorous so they eat small animals, birds, reptiles, insects and plants. They have some competition in getting their food, but they're good hunters.

The corsac fox is found throughout the southeast area of the former USSR and a large area of central Asia. They are also found in Turkestan, Afghanistan, Mongolia, Transbaikalia, and northern Manchuria.

Corsac fox mate between January and March with a gestation time that lasts 50-60 days. Typically between 2 and 6 young are born at a time, but there are some reported cases of a litter of up to 11 young. It is thought that the dog fox probably helps rear young but this is not known for certain. Males will fight with one another during the breeding season but then remain with the family pack. They live for 3 to 12 years.

They are more social than other foxes and some Corsac foxes go with others in burrows and form hunting packs. They can hear, smell and see very well. The hardest way for the Corsac Fox to escape an enemy is to run, because they run so slowly that a slow dog could catch them. They don't seem to have a home range that they protect from other foxes and migrate south when the food gets scarce.

The Corsac Foxes are not well spread around the steppe. Although hunting by humans has eliminated large groups, there are no conservation program for the Corsac Fox. Very little is known about the Corsac Fox but hunting and the plowing of land have significantly reduced their numbers. The fox has disappeared over much of its range.

Mongolian Gerbil

Genus: Meriones

Species: unguiculatus

The Mongolian Gerbil is light brown with black tipped hairs and its under fur is gray. They are the size of any pet gerbil. They live in burrows with sandy soil and a little bit of grass, herbs and shrubs. They eat seeds, roots, vegetables and drink water. When they eat seeds, they spread them to different areas and make new plants in that area.

In the gerbil family there are 2 to 17 gerbils, but there are more males than females. They live together by age. For example, the older ones live with the older ones and the younger ones

live wit the younger ones. In the family, older gerbils take care of the younger gerbils and males take care of the females.

Mongolian Gerbils live in harsh conditions but do not have many enemies. When ever they come across an enemy, they use their strong legs so they can jump really high to escape the enemy or they can use their strong legs to help them dig really fast to escape the enemy.

They do not have much competition with getting their food because all the other animals that eat what they eat are smaller than them.

They are not well spread around the steppe, but they are not endangered.

Saiga Antelope

Common Name: Mongolian Saiga

Genus: Saiga

Species: tatarica

The Saiga antelope once roamed from western Europe, across the Eurasian continent and into Alaska. It now only lives in areas of the dry steppes and semi deserts of Mongolia, Kazakhstan, and Kalmykia.

The Saiga is a very curious looking animal. Most remarkable about it is its huge nose. This inflatable, humped, and movable nose looks very similar to the noses of tapirs or dik-diks, and makes the head look unusually large, and bulging. The Saiga's nose is actually an adaptation to the extremely cold and dusty environment in which it lives. Its internal structure is composed of an intricate network of

bones, hairs, and mucous-secreting glands. During summer migrations it helps filter out dust kicked up by the herd and cools the animals blood. During the winter it heats up the frigid air before it is taken into the lungs, thereby reducing heat loss in its body.

The Saiga's large eyes are set at the end of bony knobs on either side of its head, giving it a bug-eyed look. Their eyesight is keen, and they can see up to .6 miles away.

The short, round body, which can reach from 3.8 to 4.8 feet in length, is supported by thin legs. They are, however, very good runners and can run up to 48 mph for short periods. They stand 2 to 2.6 feet high at the shoulders. The short tail is 2.4 to 5.2 inches in length. Saigas can weigh from 46 to 112 lbs.

The females are slightly smaller and don't have the male's horns. These wax-colored horns are almost translucent, and are tapered, heavily ridged, and very sharp. They can grow 10 inches long.

The Saiga has a woolly undercoat and an outercoat of coarse, bristly hairs which protect it from the cold environment it lives in. In the summer it has a cinnamon-buff coat which is rather thin compared to their winter coats.

Their winter coat is almost entirely white and twice as long, and 70% thicker than their summer coat. The hair under its neck tends to be longer. The hair on their legs stays short.

Saigas are harem breeders and breed in late November to late December. Males will herd together a group of about 12 females, and mark a breeding territory. While defending it against other males, fierce fights break out. Sometimes they end in the death of one of the saiga males. Huge amounts of energy are spent defending territories, and because of the extreme winters, 97% of the sexually mature males will not survive.

Those males that do survive start off on their spring migration in April, forming herds of 10 to 2,000 animals. The females in the meantime collect in large herds to an appropriate breeding area, where they give birth to one or two calves each.

Eight to ten days after giving birth, they set out northwards after the males. Once at their summer pastures they break up into smaller groups. Large groups form again in the fall, when the southward migration takes them back to the winter grounds.

Gestation in a Saiga lasts 140 days. Young females will usually give birth to a single calf the first year, but then have two calves the following years. Calves are born at the end of March, beginning April, when all the females in a herd drop their calves within a few days of each other. The calves are weaned at 3 to 4 months. Sexual maturity is 8 months for females and 20 months for males. Saigas live for 6 to 10 years.

Saiga antelope are herbivores and eat grasses, prostrate summer cypress, saltworts, sagebrush, and lichens. They are ruminants and will rest to chew their cud after eating in the early morning and late afternoon.

Cud is food that is regurgitated and chewed again. This helps the Saiga extract the maximum nutrients from the food they eat. Their natural predators are wolves, and foxes, which prey on newborn calves.

The Saiga's horn has been used in traditional Chinese medicine for centuries. Whole herds were slaughtered for their horns, and the Saiga populations declined rapidly. In the 1980s the Saiga had made a sizable recovery after nearly being driven into extinction earlier in the century.

With the breakup of the Soviet Union, illegal trade in Saiga horns is once again on the increase. The Saiga was classified as vulnerable by the IUCN in 1996. An animal is considered vulnerable when it is not critically endangered or endangered but is facing a high risk of extinction in the wild in the near future.

It is also listed in the CITES Appendix II. A permit is necessary to trade in Saigas and Saiga parts. Law enforcement, however, is difficult in the areas where Saigas can still be found.

Northern Lynx

Common Names:

Genus: Felis

Species: lynx

The northern lynx is basically a very large cat with a powerful body, short sturdy legs, and a very short tail. They have large heads, and long tufted ears which stand straight up. Their coats are usually yellowish-brown and white on its undersides. The average weight of the northern lynx is 30 to 65 pounds. Their tails grow up to 7 inches.

The northern lynx can be found on the steppes of Asia. They also like to live in forests and rocky places of Canada, the northern United States and in fragmented areas of Europe.

The northern lynx always hunts for rodents, birds, fish, small deer, goats,

or sheep. They usually live and hunt alone, and are nocturnal hunters. Sometimes northern lynx will hunt in pairs. Their mating season may be in January, but is normally in late February or in early March.

They give birth to 2 or 3 kittens at a time. The females stay pregnant for 68 to 72 days, and give birth in a lair in a hollow tree, rock cleft, or a similar site. The kittens stay with their mother until the next mating season. Siblings usually continue to stay together after they leave their mother.

Northern lynx can climb well and are good swimmers which help them when hunting. They have very good vision, which helps them to stalk their prey over long distances. Northern lynx may jump 7 feet into the air to catch birds and they use their broad and long feet as snow shoes to keep them from sinking into the snow.

They help in their environment by keeping the rodent population down which is important because they multiply very quickly. They also eat large sick and almost dead animals.

There are not many northern lynx left in the world, partly because hunting the lynx is still permitted in the United States and Canada. People continue to hunt them for their fur and also for sport.

Saker Falcon

Common Names: Saker Falcon, Altai Saker, Steppe Saker

Genus: Falco

Species: cherrug

The saker falcon is a big, strong bird of prey with large feet and pointed wings. It is larger than the peregrine falcon, and has a very wide wingspan for its size. There are several subspecies of saker falcons; the steppe Saker (Falco cherrug cherrug), the mountain Saker (Falco cherrug milvipes), and the Altai Saker (Falco cherrug altaicus ). The saker falcon has a large range of color, from dark brown to grey, to almost white. Saker falcons are also thought to breed with gyrfalcons and form a hybrid falcon.

The saker falcon originated in southeast Europe and Asia. Their preferred habitats are the open plains and forest steppes. They can be found on the steppes of Mongolia and of

southern Siberia, and the Russian Altai mountains.

The saker falcon is about 18 inches tall. They have large eyes and a short, hooked beak. Steppe saker falcons use the nests of Black Kites (Milvus migrans) and Imperial Eagles (Aquila heliaca). The mountain saker build its nest on cliffs. Saker falcons lay 2 to 5 eggs. In the winter they migrate south to Kazakhstan and the Middle East.

They spent most of their time hunting for mammals like voles, rats, stoats, weasels, northern pikas, Siberian chipmunks, and birds. They dive for their prey at 200 mph. The saker falcon are ferocious hunters and often attacks prey that is bigger than itself. Female saker falcons are more ferocious than the males and are preferred by falconers. In the wild they have no natural enemies, except man.

The larger, dark brown and gray barred Altai Saker falcons are the favorite bird of Arab falconers. Many of the birds are trapped in Arab countries when they are on their migration to the Middle East. In the past it was the custom to capture juvenile female sakers and train them to hunt because they were easier to train than adult birds.

Because the birds have become scarce, both adult and juvenile birds are now being caught throughout Asia and sold to the Middle Eastern falcon market. Without breeding adults in the wild, the saker falcon's population is in danger of declining.

There are no accurate figures for the population of Saker falcons, but it is believed that there are only 1,000 pairs of birds left in Russia, and 130 pairs in the rest of Europe. Some scientists think the decline of the steppe Saker is caused by the regional extinction of their preferred prey, the Red-cheeked Sousliks (Citellus erythrogenys), which is a type of ground squirrel.

Global temperature changes has brought about changes in the vegetation on which the sousliks survived. Because the climate changed, the plants which Sousliks ate died, which caused the Sousliks to die off in that region, which is causing the Steppe Saker falcon population to decline. There are only about 200 pairs of Steppe Saker falcons left and they may become extinct in the next 10 to 15 years.

This lapwing is the only crested wader in South America. It is 31-33cm in length and weighs 295g. The upperparts are mainly brownish grey, with a bronze glossing on the shoulders. The head is particularly striking; mainly grey with a black forehead and throat patch extending onto the black breast. A white border separates the black of the face from the grey of the head and crest. The rest of the underparts are white, and the eyering, legs and most of the bill are pink.

During its slow flapping flight, the Southern Lapwing shows a broad white wing bar separating the grey-brown of the back and wing coverts from the black flight feathers. The rump is white and the tail black.

The sexes are similar in plumage, but young birds are duller, with a shorter crest and browner face and breast. There are four geographical races of Southern Lapwing, differing mainly in the details of the black and white face pattern. The call is a very loud and harsh keek-keek-keek.

Habitat and numbers

This is a Lapwing of lake and river banks or open grassland. It has benefited from the extension of the latter habitat through widespread cattle ranching. It was first recorded on Trinidad in 1961 and Tobago in 1974, and has rapidly increased on both islands.

Habits and movements

Southern Lapwing breeds on grassland and sometimes ploughed fields, and has an aerobatic flapping display flight. It lays 2-3 olive brown eggs in a bare ground scrape. The nest and young are defended noisily and aggressively against all intruders. When not breeding, this bird disperses into wetlands and seasonally flooded tropical grassland.

Food

Its food is mainly insects and other small invertebrates, hunted by a run-and-wait technique, mainly at night. This gregarious species often feeds in flocks.

Rheas are polygamous, with males courting between two and twelve females. After mating, the male builds a nest, in which each female lays her eggs.

The male incubates from ten to sixty eggs; the chicks hatch within 36 hours of each other. The females, meanwhile, may move on and mate with other males.

While caring for the young, the males will charge at anyone — including humans and female rheas — who approaches

the chicks.

Rheas are omnivorous, preferring broad-leafed plants, but also eating seeds, roots, fruit, insects, and small vertebrates.

Rhea americanus (also called the Gray or Common Rhea) is not only the largest species of rhea but the largest American bird, with adults averaging 30 kilograms (66 lb).

Farmers sometimes consider them pests, because they will eat almost any crop plant. Because of this habit, farmers sometimes kill the birds. This, along with egg gathering and habitat loss, has led to a sharp population decline; the species is listed as being of "special concern." They do not eat most crop plants, but they will eat brassicas (cabbage, and baby chard and bok choi) if very hungry soybean leaves. Rheas disdain grasses.

American Rheas live in grassland, savanna, scrub forest, chaparral, and even desert, but prefer areas with at least some tall vegetation. During breeding season (which ranges from August to January in South America, April to August in North America), they stay near water.

Male rheas are very territorial during breeding season. The infant chicks are highly intolerant of toxins, having high mortality in typical farming situations. Baby chicks under optimum conditions will grow to four feet tall by their fifth month.

Rheas have an incredible immune system that allows injured birds to heal rapidly with little intervention. This is reflected in the commercial uses of the animal. The fat of the birds is used as an anti-inflammatory salve.

Use of the meat as an energy supplement is patented in the U.S. and Canada by an American woman who has spent 12 years working to reduce chick mortality and provide a commercial basis for the species, trying to ensure its long-term survival.

The American Rhea is a threatened species as listed in CITES.

Rhea pennatus (Darwin's Rhea, synonyms R. darwini, R. macrorhyncha, Pterocnemia pennata) is 90 to 100 centimeters (3 ft to 3 ft 4 in) tall, and has larger wings than other ratites, enabling it to run particularly well. They can reach speeds of 60 km/hour, enabling them to outrun predators. The sharp claws on the toes are effective weapons.

The males of this species become aggressive once they are incubating eggs. The females thus lay the later eggs near the nest, rather than in it. Most of the eggs are moved into the nest by the male, but some remain outside, where they rot and attract flies. The male, and later the chicks, eat these flies.

Outside the breeding season, Darwin's rheas are quite sociable: they live in groups of from 5 to 30 birds, of both sexes and a variety of ages.

Darwin's Rhea lives in areas of open scrub in the grasslands of Patagonia and on the Andean plateau. It is classified as endangered throughout its range.

grazing (MIG), and improvements in fence technology, led to renewed interest in grazing in the 1990s. Pasture growth can consist of grasses, legumes, or a mixture. Alfalfa, clover, and birdsfoot trefoil are legumes used in intensive pasture management.

Many grasses, including ryegrass (Lolium), meadow-grass (Poa), foxtails (Alopecurus), and bents (Agrostis) are used, depending upon conditions, of which soil type, minimum annual temperature, and rainfall amount are most important.

Hummingbirds are small birds in the family Trochilidae. They are known for their ability to hover in mid-air by rapidly flapping their wings, 15 to 80 times per second (depending on the size of the bird).

Unlike other bird species capable of limited hovering, the hummingbird is alone in its ability to fly deliberately backwards or vertically, and to maintain position for drinking from flower blossoms. They are named for the characteristic hum made by their wings.

Hummingbirds are attracted to many flowering plants—shrimp plants, Heliconia, bromeliads, verbenas,

fuchsias, many penstemons—especially those with red flowers. They feed on the nectar of these plants and are important pollinators, especially of deep-throated flowers. Most species of hummingbird also take insects, especially when feeding young.

The Bee Hummingbird (Mellisuga helenae) is the smallest bird in the world, weighing 1.8 g. A more typical medium-sized hummingbird, such as the Rufous-tailed weighs approximately 3 g and has a length of 10-12 cm (3.5-4 inches).

Most male hummingbirds take no part in nesting. Most species make a neatly woven cup in a tree branch. Two white eggs are laid, which despite being the smallest of all bird eggs, are in fact large relative to the hummingbird's adult size. Incubation is typically 14-19 days.

is also known by the regional names of cougar, mountain lion, panther, catamount, painter, American lion, Mexican lion, Florida panther, silver lion, red lion, red panther, red tiger, brown tiger, deer tiger, ghost cat, mountain screamer, Indian devil, sneak cat, king cat, and painted cat.

The word puma comes from the Quechua language. In Brazil it is also known as suçuarana, from the Tupi language, but also has other names. In fact in the English language the puma has over 40 different names. In North America, particularly the United States, panther by itself refers to a puma when the context implies a local species, although the term black panther is correctly associated only with the melanistic variants of leopards or jaguars rather than pumas.

In Europe and Asia, panther means leopard and can refer to either the spotted or black leopard. In South America, panther refers to the jaguar and can refer to either the spotted or black jaguar. The melanistic gene can be seen in a variety of cats, including the lion, tiger, leopard, jaguar, caracal, jaguarundi, serval, ocelot, margay, bobcat, lynx, and Geoffroy's Cat; however, melanism has never been documented in Puma concolor, although urban legends of "black panthers" persist.

Such anecdotal accounts are particularly prominent in the Appalachian Mountains of the eastern United States, a region where P. concolor is accepted as having been wholly extirpated by the late 1800's, and where breeding populations have not been documented as re-established by 2005.

Recent DNA analysis has established that the puma is supposedly quite closely related to the jaguarundi and North American cheetah (Miracinonyx, now extinct), but not to true cheetahs. The puma is not closely related to other large felines, such as leopards and lions. There is a considerable variation in color and size of these animals across their large range of habitats.

Depending on the species, male deer are called stags, harts, bucks or bulls, and females are called hinds, does or cows. Young deer are called calves or fawns (not to be confused with fauns, a kind of nature spirit).

Hart is an expression for a stag, particularly a Red Deer stag past its fifth year. It is not commonly used, but an example is in Shakespeare's "Romeo and Juliet" when Tybalt refers to the brawling Montagues and Capulets as hartless hinds. "The White Hart" and "The Red Hart" are common English pub names.

Deer are widely distributed, and hunted, with representatives in all continents except Australia, Antarctica, and Africa.

Australia does have six introduced species of deer that have established sustainable wild populations from Acclimatisation Society releases in the 19th Century. These

are Fallow Deer, Red Deer, Sambar Deer, Hog Deer, Rusa deer, and Chital Deer[1].

Although exotic to the continent, environmental factors restrict their ranges to habitable patches, thereby preventing any one species from becoming a serious pest. Red Deer introduced into New Zealand in early 1900s (a gift from United States President Theodore Roosevelt) have been largely domesticated in deer farms since the late 1960s and are common farm animals there now.

Deer differ from other ruminants in that they have antlers instead of horns. Antlers are bony growths that develop each year (usually in summer) and, in general, it is only male deer that develop them (although there are exceptions). A young buck's first pair of antlers grow from two tiny bumps on their head that they have had from birth.

The antlers grow wrapped in a thick layer of velvet and remain that way for one month, until the bone inside is hard; later the velvet is shed. During the mating season, bucks use their antlers to fight one another for mates. The two bucks circle each other, bend back their legs, lower their heads, and charge.

A doe generally has one or two fawns at a time (triplets, while not unusual, are much more infrequent). The gestation period is anywhere between 160 days (just over 5 months) in the musk deer to ten months for the roe deer. Most fawns are born with their fur covered with white spots, though they lose their spots once they get older (excluding the Fallow Deer who keeps its spots for life).

In the first twenty minutes of a fawn's life, the fawn begins to take its first steps. Its mother licks it clean until it is almost free of scent, so predators will not find it. Its mother leaves often, and the fawn does not like to be left behind. Sometimes its mother must gently push it down with her foot. The fawn stays hidden in the grass for one week until it is strong enough to walk with its mother.

After two days, a fawn is able to walk, and by three weeks it can run and jump. The fawn and its mother stay together for about one year. They then go their separate ways. A male usually never sees his mother again, but females sometimes come back with their own fawns and form small herds.

Deer generally have lithe, compact bodies and long, powerful legs suited for rugged woodland terrain. Deer are also excellent swimmers. Their lower cheek teeth have crescent ridges of enamel, which enable them to grind a wide variety of vegetation. Deer are ruminants or cud-chewers and have a four-chambered stomach. Nearly all deer have a facial gland in front of each eye.

The gland contains a strongly scented substance called pheromone, used to mark its home range. Bucks of a wide range of species open these glands wide when angry or excited. Except for the musk deer, all deer have a liver without a gallbladder. The musk deer, along with the Chinese water deer also differ from other species in that they have no antlers and bear upper canines developed into tusks.

There are about 34 species of deer worldwide, divided into two broad groups: the old world group includes the subfamilies Muntiacinae and Cervinae; the new world deer the subfamilies Hydropotinae and Capreolinae.

Note that the terms indicate the origin of the groups, not their modern distribution: the Water Deer, for example, is a new world species but is found only in China and Korea. It is thought that the new world group evolved about 5 million years ago in the forests of North America and Siberia, the old world deer in Asia.

They are very fast moving. The European Brown Hare (Lepus europaeus) can run at speeds of up to 70 km/h (45 mi/h). Hares live solitarily or in pairs.

A common type of hare in arctic North America is the Snowshoe Hare, replaced further south by the Black-tailed Jackrabbit, White-tailed Jackrabbit and other species.

Normally a shy animal, the European Brown Hare changes its behaviour in spring, when hares can be seen in broad daylight chasing one another around meadows; this appears to be competition between males to attain dominance (and hence more access to breeding females).

During this spring frenzy, hares can be seen "boxing"; one hare striking another with its paws. For a long time it had been thought that this was more inter-male competition, but closer observation has revealed that it is usually a female hitting a male; either to show that she is not yet quite ready to mate, or as a test of his determination.

Hares do not bear their young below ground in a burrow as do other Leporidae, but rather in a shallow depression or flattened nest of grass called a form. Young hares are adapted to the lack of physical protection offered by a burrow by being born fully furred and with eyes open.

They are hence able to fend for themselves very quickly after birth, that is to say they are precocial. By contrast, the related rabbits and cottontail rabbits are altricial, having young that are born blind and hairless. The hare's diet is very similar to that of the rabbit.

An owl is a member of any of 222 currently known species of solitary, mainly nocturnal birds of prey in the order Strigiformes. Owls mostly hunt small mammals, insects, and other birds, though a few species specialize in hunting fish.

They are found on all continents of the Earth except Antarctica, most of Greenland, and some remote islands. Though owls are typically solitary, the literary collective noun for a group of owls is a parliament. Owls are classified in two families: the typical owls, Strigidae, and the barn owls, Tytonidae.

Owls have large forward-facing eyes and ears, a hawk-like beak, and usually a conspicuous circle of feathers around each eye called a facial disc. Although owls have binocular vision, their large eyes are fixed in their sockets, and they must turn their entire head to change views.

Owls are far-sighted, and are unable to clearly see anything within a few inches of their eyes. Their far vision, particularly in low light, is incredibly good, and they can turn their head 180 degrees around.

Many owls can also hunt by sound in total darkness. Different species of owls make different sounds, one of which is the widely recognizable, drawn-out "hoo" sound. The facial disc helps to funnel the sound of prey to their ears, which are widely spaced. In some species, they are placed asymmetrically, for better directional location.

Despite their appearance, owls are more closely related to the nightjars (Caprimulgiformes) than to the diurnal predators in the order Falconiformes. Some taxonomists place the nightjars in the same order as owls, as in the Sibley-Ahlquist taxonomy .

Owls' powerful clawed feet and sharp beak enable them to tear their prey to pieces before eating, although most items are swallowed whole. Their muffled wings and dull feathers allow them to fly practically silent and unseen.

Scientists studying the diets of owls are helped by their habit of disgorging the indigestible parts of their prey (bones, scales, fur, etc.) in the form of pellets. These "owl pellets" are often sold by companies to schools to be dissected by students as a lesson in biology and ecology, because they are plentiful and easy to interpret.

Owl eggs are white and almost spherical, and range in number from a few to a dozen dependent on species. Their nests are crudely built and may be in trees, underground burrows or barns and caves.

Most owls are nocturnal, but several, including the pygmy owls (Glaucidium), are crepuscular, or twilight active, hunting mainly at dawn and dusk. A few owls, such as the Burrowing Owl (Speotyto cunicularia) and the Short-eared Owl (Asio flammeus), are also active during the day.

The smallest owls include the pygmy owls, some of which are only 13 cm (5.1 in) long, have a 32-cm (12.6-in) wingspan, and weigh only 50 g (1.76 oz). The largest owls are the eagle owls, the Eurasian Eagle Owl Bubo bubo and Verreaux's Eagle Owl B. lacteus, which may reach 71 cm (28 in) long, have a wingspan of just over 2 m (6.6 ft), and weigh about 4 kg (almost 9 lb).

Although the term savanna is believed to have originally come from an Amerindian word describing "land which is without trees but with much grass either tall or short" (Oviedo y Valdes, 1535), by the late 1800s it was used to mean "land with both grass and trees".

It now refers to land with grass and either scattered trees, or an open canopy of trees.

Native Americans created subtropical savannas by periodic burning in some areas of the US southeastern coast where fire-resistant Longleaf Pine was the dominant species. Most other tree species were killed, resulting in widely-spaced longleaf pines with grassland between the trees. Savannah, Georgia is named after such an area. Farther north, as in between Seneca Lake and Cayuga Lake in the Finger Lakes of New York, such burning killed all the trees and created prairie instead.

Savanna ecoregions are of several different types: Tropical and subtropical savannas are classified with tropical and subtropical savannas and shrublands as the tropical and subtropical grasslands, savannas, and shrublands biome. The savannas of Africa, including the Serengeti, famous for its wildlife, are typical of this type.

Temperate savannas are mid-latitude savannas with wetter summers and drier winters. They are classified with temperate savannas and shrublands as the temperate grasslands, savannas, and shrublands biome.

Mediterranean savannas are mid-latitude savannas in Mediterranean climate regions, with mild, rainy winters and hot, dry summers, part of the Mediterranean forests, woodlands, and shrub biome. The oak tree savannas of California, part of the California chaparral and woodlands ecoregion, fall into this category.

Flooded savannas are savannas that are flooded seasonally or year-round. They are classified with flooded savannas as the flooded grasslands and savannas biome, which occurs mostly in the tropics and subtropics.

Montane savannas are high-altitude savannas, located in a few spots around the world's high mountain regions, part of the montane grasslands and shrublands biome. The highland savannas of the Angolan scarp savanna and woodlands ecoregion are an example.

The rhinoceros (commonly called rhino for short; plural can be either rhinoceros or rhinoceroses) is any of five surviving species of odd-toed ungulates in the family Rhinocerotidae.

All five species are native to Africa or Asia. Rhinoceros is

also one of the genera in this family.

The family is characterised by: large size (one of the few remaining megafauna surviving today) with all of the species capable of reaching one tonne or more in weight; a horn on the centre of the forehead (sometimes with a second one

behind it); herbivorous diet; and a thick protective skin, 1.5-5 cm thick, formed from layers of collagen positioned in a lattice structure. Rhinoceros also have acute hearing and sense of smell, but poor eyesight over any distance. Most rhinoceros live to be about 40 years old. A male rhinoceros is called a bull, a female a cow, and the young a calf; a group of rhinoceros is called a "crash".

Rhinoceros, despite being herbivorous, are dangerous animals. In India and Nepal, the Indian rhinos cause the greatest number of human deaths each year, surpassing those caused by tigers and leopards. They have been known to charge even working elephants carrying tourists through the jungles.

The most obvious distinguishing characteric of the rhinos is a large horn above the nose. The word rhinoceros comes from the Greek words rhino (nose) and keros (horn). Rhinoceros horns, unlike those of other horned mammals, consist of keratin.

Rhinoceros horns are used in traditional Asian medicine, and for dagger handles in Yemen and Oman. None of the five rhinoceros species have secure futures; the White Rhinoceros is perhaps the least endangered, the Javan Rhinoceros survives in only tiny numbers (estimated at 60 animals in 2002) and is one of the two or three most endangered large mammals anywhere in the world.

Rhino protection campaigns began in the 1970s, but rhino populations have continued to decline dramatically. Trade in rhinoceros parts is forbidden under the CITES agreements, but poaching is a severe threat to all rhinoceros species.

The giraffe is related to deer and cattle, but is placed in a separate family, the Giraffidae, consisting only of the giraffe and its closest relative, the okapi.

The species name camelopardalis (camelopard) is derived from its early Roman name, where it was described as having characteristics of both a camel and a leopard (and perhaps being a hybrid of the two).

The instinct of some other African animals is to stay close to the giraffe, for the giraffe's high vantage point can see predators from far away.

The average weight of a male African Lion is 190 kg (420lb). The biggest wild lion on record was a very large male which

weighed in at 312.7 kg (688 lb). Female lions are much smaller, weighing between 117 and 167kg (240 lb and 370 lb). In the wild, lions live for around 10–14 years, while in captivity they can live over 20 years. To reproduce, the lions mate for long periods of time.

Elephantidae (the elephants) is a family of pachyderm, and the only remaining family in the order Proboscidea. Elephantidae has three living species: the African Bush Elephant and the African Forest Elephant (which were collectively known as the African Elephant) and the Asian Elephant (formerly known as the Indian Elephant).

Other species have become extinct since the last ice age, which ended about 10,000 years ago.

Elephants are mammals, and the largest land animals alive today. The elephant's gestation period is 22 months, the longest of any land animal. At birth it is common for an elephant calf to weigh 120 kg (265 lb).

An elephant may live as long as 70 years, sometimes longer if various bone diseases can be caught early. The largest elephant ever recorded was shot in Angola in 1974. It was male and weighed 12,000 kilograms (26,400 lb). The smallest elephants, about the size of a calf or a large pig, were a pre-historic variant that lived on the island of Crete until 5000 BC, possibly 3000 BC.

Their scattered skulls, featuring a single large trunk-hole at the front, perhaps formed the basis of belief in existence of cyclops, one-eyed giants featured in Homer's Odyssey. Recent findings of animal remains in central China show Prehistoric humans ate elephants. The elephant is now a protected animal, and keeping one as a pet is prohibited around the world.

evening)

There are three species and many subspecies. Zebra populations vary a great deal, and the relationships between and the taxonomic status of several of the subspecies are unclear.

The Plains Zebra (Equus quagga, formerly Equus burchelli) is the most common, and has or had about five subspecies distributed across much of southern and eastern Africa. It, or particular subspecies of it, have also been known as the Common Zebra, the Dauw, Burchell's Zebra (actually the subspecies Equus quagga burchelli), and the Quagga (another, extinct, subspecies, Equus quagga quagga).

The Mountain Zebra (Equus zebra) of southwest Africa tends to have a sleek coat with a white belly and narrower stripes than the Plains Zebra. It has two subspecies and is classified as endangered.

Grevy's Zebra (Equus grevyi) is the largest type, with an erect mane, and a long, narrow head making it appear rather mule-like. It is an inhabitant of the semi-arid grasslands of Ethiopia, Somalia, and northern Kenya. The Grevy's Zebra is one of the rarest species of zebra around today, and is classified as endangered.

Characteristics

Hippopotamuses (hippopotami is also accepted as a plural form by the OED), also sometimes called hippos, are gregarious, living in groups of up to 40 animals; such a group is called a pod, herd, school, or bloat. A male hippopotamus is known as a bull, a female as a cow, and a baby as a calf. A hippo's lifespan is typically 40 to 50 years. Female hippos reach sexual maturity at 5 to 6 years and have a gestation period of 8 months. Donna the Hippo, 55, is the oldest known hippo in captivity. She lives at the Mesker Park Zoo in Evansville, Indiana.

Hippos average 3.5 meters (11 ft) long, 1.5 meters (5 ft) tall at the shoulder, and weigh from 1,500 to 3,200 kilograms (3,300 to 7,000 lb). They are approximately the same size as the White Rhinoceros, and experts are split on which is the largest land animal after the different species of elephant. Male hippos appear to continue growing throughout their lives, whereas the females reach a maximum weight at around age 25. Females are smaller than their male counterparts and normally weigh no more than 1,500 kg.

The value of 3,200 kg is often quoted as being the upper limit of weight for a male hippo. However, larger specimens than this have been documented, including one which weighed about 4,500 kg (10,000 lb) and measured about 5 meters (16 ft) long. Their skin is 4 centimeters (1.5 in) thick, and accounts for 25% of their weight.

Even though they are bulky animals, hippopotamuses can run faster than a human on land. There are estimates of their running speed varying from 30 km/h (18 mph) to 40 km/h (25 mph), or even 50 km/h (30 mph). The hippo can maintain these higher estimates for only a few hundred meters or yards.

The eyes, ears, and nostrils of the hippo are placed high on the roof of the skull. This allows them to spend most of the day with the majority of their body submerged in the waters and mud of tropical rivers to stay cool and prevent sunburn.

For additional protection from the sun, their skin secretes a natural sunscreen substance which is red-colored. This secretion is sometimes referred to as "blood sweat," but is neither blood nor sweat. This secretion starts out colorless and turns red-orange within minutes, eventually becoming brown. There are two distinct pigments that have been identified in the secretions, red and orange. The two pigments are highly acidic compounds.

They are known as red pigment hipposudoric acid and orange one norhipposudoric acid. The red pigment was found to inhibit the growth of disease-causing bacteria, lending credence to the theory that the secretion has an antibiotic effect. The light absorption of both pigments peaks in the ultraviolet range, creating a sunscreen effect. Hippos all over the world secrete the pigments, so it does not appear that food is the source of the pigments. Instead, the animals may synthesize the pigments from precursors such as the amino acid tyrosine. (Saikawa, et al., 2004)

As indicated by the name, ancient Greeks considered the hippopotamus to be related to the horse. Until 1985, naturalists grouped hippos with pigs, based on molar patterns. Evidence, first from blood proteins, then from molecular systematics, and more recently from the fossil record, show that their closest living relatives are cetaceans — whales, porpoises and the like .

Hippopotami have more in common with whales than they do with other artiodactyls (even-toed ungulates), such as pigs. Thus, the common ancestor of hippos and whales existed after the branch-off from ruminants, which occurred after the divergence from the rest of the even-toed ungulates, including pigs. While the whale and hippo are each other's closest living relatives, their lineages split very soon after their divergence from the rest of the even-toed ungulates.

Hemisphere, on the Antarctic peninsula and neighboring islands. The word "tundra" usually refers only to the areas where the subsoil is permafrost, which means permanently frozen soil. (It may also refer to the treeless plain in general, so that northern Lapland would be included.) Permafrost tundra includes vast areas of northern Russia and Canada. The polar tundra is home to several peoples who are mostly nomadic reindeer herders, such as the Nganasan and Nenets in the permafrost area (and the Sami in Lapland).

The polar tundra is a vast area of stark landscape, which is frozen for much of the year. The soil there is frozen from 25-90 cm down, and so it is impossible for trees to grow. Instead, bare and sometimes rocky land can only support low growing plants such as mosses, heaths and lichen. There are two main seasons – winter and summer in the polar Tundra areas. During the winter, it is very cold and dark, with the average temperature being around -28 °C.

However, when there is no sun for several weeks – which is a common occurrence, temperatures have been known to drop to a chilling -70 °C. There is permafrost on the ground, which never completely melts. In the summer, temperatures rise and the top layer of the permafrost melts, leaving the ground very soggy. The tundra is covered in marshes, lakes, bogs and streams. Generally temperatures during the summer rise to about 12 °C, but can often drop to 3°.

The tundra is a very windy area, with winds blowing upwards of 30-60 miles an hour (48 – 97 km/h). However in terms of precipitation, it is desert-like, with only about 6 – 10 inches falling a year (mostly of snow). During the summer, the permafrost thaws just enough to let plants grow and reproduce, but because the ground below this is frozen, the water cannot sink any lower, and so the water forms the lakes and marshes found during the summer months.

The biodiversity of tundra is low: there are 1700 species of flora and only 48 land mammals can be found, although thousands of insects and plants migrate there each year for the marshes there are also a few fish species such as the flat fish. There are few species with large populations. Notable animals in the arctic tundra include caribou (reindeer), musk ox, arctic hare, arctic fox, snowy owl, lemmings, and polar bears (only the extreme north).

Due to the harsh climate of the polar tundra, regions of this kind have seen little human activity, even though they are sometimes rich in natural resources such as oil and uranium. In recent times this has begun to change in Alaska, Russia, and some other parts of the world.

Global warming is a severe threat to the polar tundra because of the permafrost. Permafrost is essentially a frozen bog; in the summer, only its surface layer melts. The melting of the permafrost in a given area on human time scales (decades or centuries) could radically change which species would survive there.

Another concern is that about one third of the world's soil-bound carbon is in taiga and tundra areas. When the permafrost melts, it releases carbon, in the form of carbon dioxide, a greenhouse gas. The effect has been observed in Alaska. In the 1970s, the tundra was a carbon sink, but today, it is a carbon source.

One example is Siberia, Russia.

Alpine tundra occurs at high enough altitude at any latitude on Earth. Alpine tundra also lacks trees, but does not usually have permafrost, and alpine soils are generally better drained than permafrost soils. Alpine tundra transitions to subalpine forests below the tree-line; stunted forests occurring at the forest-tundra ecotone are known as Krummholz.

Notable animals in the alpine tundra include, Kea parrots, marmots, Mountain goats, and pika.

Alpine tundra does not map directly to specific WWF ecoregions. Portions of Montane grasslands and shrublands ecoregions include alpine tundra. The alpine tundra also has elks,marmots, mountain goats, pikas, and sheep.

Taiga

Taiga (from Mongolian) is a biome characterized by coniferous forests. Covering most of inland Alaska, Canada, Sweden, Finland, and northern Russia (especially Siberia), the taiga is the world's largest terrestrial biome and a major source of oxygen. In Canada, boreal forest is the term used to refer to the southern part of this biome, while "taiga" is used to describe the more barren northern areas south of the Arctic tree-line.

Since North America and Eurasia were recently connected by the Bering land bridge, a number of animal and plant species (more animals than plants) were able to colonise both continents and are distributed throughout the taiga biome. Others differ regionally, typically with each genus having several distinct species, each occupying different regions of the taiga.

The taiga biome has a harsh continental climate with a very large temperature range between summer and winter, classified as "Dfc" or "Dfb" in the Köppen climate classification scheme. Aside from the tundra and permanent ice caps, it is the coldest biome on Earth. High latitudes mean that, for much of the year the sun hovers at the horizon; winters last at least 6 months, with average temperatures below freezing. Temperatures vary from -50 °C to 30 °C throughout the whole year, with 8 or more months of temperatures averaging below 10 °C.

The summers, while short, are generally warm and humid. In general, taiga grows north to the 10 °C July isotherm, occasionally to the 9 °C July isotherm (Arno & Hammerly 1984, Arno et al. 1995). The southern limit is more variable, depending on rainfall; taiga may be replaced by open steppe woodland south of the 15 °C July isotherm where rainfall is very low, but more typically extends south to the 18 °C July isotherm, and locally where rainfall is higher (notably in eastern Siberia and adjacent northern Manchuria) south to the 20 °C July isotherm.

In these warmer areas, the taiga has higher species diversity with more warmth-loving species such as Korean Pine, Jezo Spruce and Manchurian Fir, and merges gradually into mixed temperate forest, or more locally (on the Pacific Ocean coasts of North America and Asia) into coniferous temperate rainforests.

The taiga experiences relatively low precipitation throughout the year (200-750 mm annually), primarily as rain during the summer months, but also as fog and snow; as evaporation is also low for most of the year, precipitation exceeds evaporation and is sufficient for dense vegetation growth. Snow may remain on the ground for as long as nine months in the northernmost extensions of the taiga (Sayre, 16).

Much of the area currently classified as taiga was recently glaciated. As the glaciers receded, they gouged out depressions in the topography. These depressions have since filled with water, creating lakes and bogs (especially muskeg soil), found throughout the taiga.

Soils

Taiga soil tends to be young and nutrient-poor; it lacks the deep, organically-enriched profile present in temperate deciduous forests (Sayre, 19). The thinness of the soil is due largely to the cold; it hinders the development of soil, as well as the ease with which plants can use its nutrients (Sayre, 19). Fallen leaves and moss can remain on the forest floor for a long time in the cool, moist climate, which limits their organic contribution to the soil; acids from evergreen needles further leach the soil, creating spodosol (Sayre, 19-20).

Flora

There are two major types of taiga, closed forest, consisting of many closely-spaced trees with mossy ground cover, and lichen woodland, with trees that are farther-spaced and lichen ground cover; the latter is more common in the northernmost taiga (Sayre, 12-3).

The forests of the taiga are largely coniferous, dominated by larch, spruce, fir, and pine. Evergreen species in the taiga (spruce, fir, and pine) have a number of adaptations specifically for survival in harsh taiga winters, though larch, the most cold-tolerant of all trees, is deciduous.

Taiga trees tend to have shallow roots to take advantage of the thin soils, while many of them seasonally alter their biochemistry to make them more resistant to freezing, called "hardening" (Sayre, 23). The narrow conical shape of northern conifers, and their downward-drooping limbs, also help them shed snow (Sayre, 23).

Because the sun is low in the horizon for most of the year, it is difficult for plants to generate energy from photosynthesis. Pine and spruce do not lose their leaves seasonally and are able to photosynthesize with their older leaves in late winter and spring when light is good but temperatures are still too low for new growth to commence.

The adaptation of evergreen needles limits the water lost due to transpiration and their dark green color increases their absorption of sunlight. Although precipitation is not a limiting factor, the ground freezes during the winter months and plant roots are unable to absorb water, so desiccation can be a severe problem in late winter for evergreens.

Although the taiga is dominated by coniferous forests, some broadleaf trees also occur, notably birch, aspen, willow, and rowan. Many smaller herbaceous plants grow closer to the ground. Periodic stand-replacing wildfires (with return times of between 20-200 years) clear out the tree canopies, allowing sunlight to invigorate new growth on the forest floor.

For some species, wildfires are a necessary part of the life cycle in the taiga; some, e.g. Jack Pine have cones which only open to release their seed after a fire, dispersing their seeds onto the newly cleared ground. Grasses grow wherever they can find a patch of sun, and mosses and lichens thrive on the damp ground and on the sides of tree trunks. In comparison with other biomes, however, the taiga has a low biological diversity.

Fauna

The taiga is home to a number of large herbivorous mammals and smaller rodents. These animals have also adapted to survive the harsh climate. Many of the larger mammals, such as black bears, eat during the summer in order to gain weight and then go into hibernation during the winter. Other animals have adapted layers of fur or feathers to insulate them from the cold.

Due to the climate, carnivorous diets are an inefficient means of obtaining energy; energy is limited, and most energy is lost between trophic levels. However, predatory birds (owls and eagles) and other smaller carnivores, including foxes and weasels, feed on the rodents. Larger carnivores, such as lynxes and wolves, prey on the larger animals. Omnivores, such as bears and raccoons are fairly common, sometimes picking through human garbage.

A considerable number of birds such as Siberian Thrush, White's Thrush and Dark-throated Thrush, migrate to this habitat to take advantage of the long summer days and abundance of insects found around the numerous bogs and lakes. Of the perhaps 300 species of birds that summer in the taiga, only 30 stay for the winter (Sayre, 28). These are either carrion-feeding or large raptors that can take live mammal prey, including Golden Eagle, Rough-legged Buzzard, and Raven, or else seed-eating birds, including several species of grouse and crossbills.

Kingdom: Plantae

Division: Bryophyta

Class: Bryopsida

Subclasses

Sphagnidae

Andreaeidae

Tetraphidae

Polytrichidae

Archidiidae

Buxbaumiidae

Bryidae

Mosses are small plants that are rarely taller than 2 inches (50 mm). They typically grow close together in clumps or mats in damp or shady locations. They do not have flowers and their simple leaves cover the thin wiry stems. At certain times mosses produces spore capsules which may appear as beak-like capsules borne aloft on thin stalks.

Overview

Botanically, mosses are bryophytes, or non-vascular plants. They can be distinguished from the apparently similar liverworts (Marchantiophyta or Hepaticae) by their multi-cellular rhizoids.

Other differences are not universal for all mosses and all liverworts, but the presence of clearly differentiated "stem" and "leaves", the lack of deeply lobed or segmented leaves, and the absence of leaves arranged in three ranks, all point to the plant being a moss. The division Bryophyta formerly included not only mosses, but also liverworts and hornworts. These other two groups of bryophytes now are often placed in their own divisions.

In addition to lacking a vascular system, mosses have a gametophyte-dominant life cycle, i.e. the plant's cells are haploid for most of its life cycle. Sporophytes (i.e. the diploid body) are short-lived and dependent on the gametophyte. This is in contrast to the pattern exhibited by most "higher" plants and by most animals. In vascular plants, for example, the haploid generation is represented by the pollen and the ovule, whilst the diploid generation is the familiar flowering plant.

Life cycle

Most kinds of plants have a double portion of chromosomes in their cells (diploid, i.e. each chromosome exists with a partner that contains the same genetic information) whilst mosses (and other bryophytes) have only a single set of chromosomes (haploid, i.e. each chromosome exists in a unique copy within the cell). There are periods in the moss lifecycle when they do have a full, paired set of chromosomes but this is only during the sporophyte stage.

Life cycle of a typical moss (Polytrichum commune)The life of a moss starts from a haploid spore, which germinates to produce a protonema, which is either a mass of filaments or thalloid (flat and thallus-like). This is a transitory stage in the life of a moss. From the protonema grows the gametophore ("gamete-bearer") that is differentiated into stems and leaves ('microphylls').

From the tips of stems or branches develop the sex organs of the mosses. The female organs are known as archegonia (sing. archegonium) and are protected by a group of modified leaves known as the perichaetum (plu. perichaeta). The archegonia have necks called venters which the male sperm swim down. The male organs are known as antheridia (singular antheridium) and are enclosed by modified leaves called the perigonium (plu. perigonia).

Mosses can be either dioicous (compare with dioecious in seed plants) or monoicous (compare monoecious). In dioicous mosses, both male and female sex organs are borne on different gametophyte plants. In monoicous (also called autoicous) mosses, they are borne on the same plant. In the presence of water, sperm from the antheridia swim to the archegonia and fertilisation occurs, leading to the production of a diploid sporophyte.

The sperm of mosses is biflagellate, i.e. they have two flagella that aid in propulsion. Without water, fertilisation cannot occur. After fertilisation, the immature sporophyte pushes its way out of the archegonial venter. It takes about a quarter to half a year for the sporophyte to mature. The sporophyte body comprises a long stalk, called a seta, and a capsule capped by a cap called the operculum.

The capsule and operculum are in turn sheathed by a haploid calyptra which is the remains of the archegonial venter. The calyptra usually falls off when the capsule is mature. Within the capsule, spore-producing cells undergo meiosis to form haploid spores, upon which the cycle can start again. The mouth of the capsule is usually ringed by a set of teeth called peristome. This may be absent in some mosses.

In some mosses, green vegetative structures called gemmae are produced on leaves or branches, which can break off and form new plants without the need to go through the cycle of fertilisation. This is a means of asexual reproduction.

Classification of mosses

Two different types of mosses (and a lichen, in the smallest box) surround this tree trunk.

Ant on mosshillMosses were traditionally grouped with the liverworts and hornworts in the Division Bryophyta (bryophytes), within which the mosses made up the class Musci. This group, however, is paraphyletic and now tends to be split up. In such system, the Division Bryophyta refers specifically to mosses. They appear to be the closest living relatives of the vascular plants.

The mosses are grouped as a single class, now named Bryopsida, and divided into seven subclasses:

Andreaeidae

Sphagnidae

Tetraphidae

Polytrichidae

Buxbaumiidae

Bryidae

Archidiidae

Andreaeidae are distinguished by the biseriate (two rows of cells) rhizoids, multiseriate (many rows of cells) protonema, and sporangium that splits along longitudinal lines. Most mosses have capsules that open at the top.

The Sphagnidae, the peat-mosses, comprise the single genus Sphagnum. These form extensive acidic bogs in peat swamps. The leaves of Sphagnum have large dead cells alternating with living photosynthetic cells. The dead cells help to store water. Aside from this character, the unique branching, thallose (flat and expanded) protonema, and explosively rupturing sporangium place it apart from other mosses.

The Tetraphidae are unique as their name implies, in having only four large peristome teeth surrounding the opening of the capsule.

Polytrichidae have leaves with lamellae, which are flaps on the leaves that look like the fins on a heat sink. These help it retain moisture. They differ from other mosses in other details of their development and anatomy too.

The Buxbaumiidae are called 'bug mosses' because they usually have a very small and reduced gametophore and the whole plant is mostly the sporophyte capsule. The shape reminds one of a bug, which is the reason for its common name.

Most (>95%) mosses belong to the Bryidae.

The Archidiidae are distinguished by their extremely large spores and the way the sporangium develops.

Habitat

The mossed tree.

Moss growing in the shelter of the growth rings of a stump

Moss on a rock

Young sporophyte of the common hair cap moss (Polytrichum commune)Mosses are found chiefly in areas of low light and dampness; any area of the world. Mosses are common in wooded areas and at the edges of streams. A few species are wholly aquatic, such as Fontinalis antipyretica, and others such as Sphagnum spp inhabit bogs, marshes and very slow-moving waterways.

Such aquatic or semi-aquatic mosses can greatly exceed the normal range of lengths seen in terestial mosses. Individual plants many inches long are common in Sphagnum species for example. Mosses are also found in cracks between paving stones in damp city streets. Some types have adapted to urban conditions and are found only in cities.

Wherever they occur, mosses require moisture to survive because of the small size and thinness of tissues, lack of cuticle (waxy covering to prevent water loss), and the need for liquid water to complete fertilisation. Some mosses can survive desiccation, returning to life within a few hours of rehydration.

In northern latitudes, the north side of trees generally will have more moss on average than other sides. This is assumed to be because of the lack of sufficient water for reproduction on the sun-facing side of trees. South of the equator the reverse is true. In deep forests where sunlight does not penetrate, mosses grow equally well on all sides of the tree trunk.

Cultivation

Moss is considered a weed in grass lawns, but is deliberately encouraged to grow under aesthetic principles exemplified by Japanese gardening. In old temple gardens, moss can carpet a forest scene. Moss is thought to add a sense of calm, age, and stillness to a garden scene. Rules of cultivation are not widely established.

Moss collections are quite often begun using samples transplanted from the wild in a water-retaining bag. However, specific species of moss can be extremely difficult to maintain away from their natural site (with its unique combination of light, humidity, shelter from wind, etc.).

Growing moss from spore is even less controlled. Moss spores fall in a constant rain on exposed surfaces—those surfaces which are hospitable to a certain species of moss will typically be colonised by that moss within a few years of exposure to wind and rain. Materials which are porous and moisture retentive, such as brick, wood, and certain coarse concrete mixtures are hospitable to moss.

Surfaces can also be prepared with acidic substances, including buttermilk, yogurt, urine, and gently puréed mixtures of moss samples, water and ericaceous compost.

Mossery

A passing fad for moss-collecting in the late 19th century led to the establishment of mosseries in many British and American gardens. The mossery is typically constructed out of slatted wood, with a flat roof, open to the north side (maintaining shade). Samples of moss were installed in the cracks between wood slats. The whole mossery would then be regularly moistened to maintain growth.

Commercial use of mosses

There is a substantial market in mosses gathered from the wild. The uses for intact moss are principally in the florist trade and for home decoration. Decaying moss in the genus Sphagnum is also the major component of peat, which is "mined" for use both as a soil additive and in smoking malt in the production of Scotch whisky.

There are growing concerns in parts of the world where this trade is growing, that significant environmental damage may be caused by the activities of commercial moss harvesters. In World War II, Sphagnum mosses were used as a sort of a band-aid on soldiers' wounds, as these mosses are highly absorbant with mild antibacterial properties. Some early people used it as a diaper due to its high absorbency.

In rural UK, Fontinalis antipyretica was traditionally used to extinguish fires as it could be found in substantial quantities in slow-moving rivers and the moss retained large volumes of water which helped extinguish the flames. This historical use is reflected in its specific Latin/Greek name, the approximate meaning of which is "against fire".

The arctic fox Occurs in two distinct colour morphs, "blue" and "white". Each colour phase also changes seasonally—"blue" moults from chocolate brown in summer to lighter brown tinged with blue sheen in winter. In winter, "white" is almost pure white, while in summer it is grey to brownish-grey dorsally, and light grey to white below. Colour morphs are determined genetically at a single locus, white being recessive. The "blue"

morph comprises less than 1% of the population through most of its continental range, but this proportion increases westwards in Alaska, and on islands. Head-and-body length: 55 cm (21.7 inches) (male); 53 cm (21 inches) (female). Tail length: 31 cm (12.2 inches) (male); 30 cm (11.8 inches) (female). Shoulder height: 25-30 cm (9.9-11.8 inches). Weight: 3.8 kg (8.2 lb) (male); 3.1 kg (6.7 lb) (female).

It is well-adapted to its habitat: its thick blubber and fur insulate it against the cold, its white color camouflages it from its prey, and it hunts well both on land and in the water. The polar bear also has a longer neck than other

types of bears, though scientists debate why.

The polar bear is a circumpolar species found in and around the Arctic Ocean whose southern range limits are determined by pack ice (its southernmost point is James Bay in Canada). While their numbers thin north of 88 degrees, there is evidence of polar bears all the way across the Arctic. Population estimates are generally just over 20,000. Their main population centers are:

Wrangel Island and western Alaska

Northern Alaska

Canadian Arctic archipelago

Greenland

Svalbard-Franz Josef Land

North-Central Siberia

Their range is limited by the availability of sea ice that they use as a platform to hunt seal, the mainstay of their diet. The destruction of its habitat on the Arctic ice, which may be caused by global warming, threatens the bear's survival as a species; it may become extinct within the century. Signs of this have already been observed at the southern edges of its range.

Size and weight

The polar bear is the largest living land carnivore, twice the weight of a Siberian tiger. Most adult males weigh from 400 to 600 kg (880 to 1300 lb) and exceptionally, up to 800 kg (1750 lb). The Kodiak sub-species of the brown bear, an omnivore, is sometimes as large. The largest polar bear on record was shot at Kotzebue Sound, Alaska in 1960. This male was estimated to weigh about 880 kg (1960 lb). Mounted, it stood 3.38 m (11 ft 11 in) high.

Females are about half the size of males and normally weigh 200 to 300 kg (450 to 650 lb). Adult males measure 2.4 to 2.6 m (95 to 102 in); females, 1.9 to 2.1 m (75 to 83 in). At birth, cubs weigh 600 to 700 g.

Beavers are best known for their natural trait of building dams in rivers and streams, and building their homes (aka lodges) in the eventual artificial pond. They are the second largest rodents, after the capybara. Beavers continue to grow throughout life. Adult specimens weighing over 25 kg (55 lb) are not uncommon. Females are as large as or

larger than males of the same age, which is uncommon among mammals.

The European Beaver (Castor fiber) was hunted almost to extinction in Europe, both for fur, and for castoreum, a secretion of its scent gland believed to have medicinal properties. However, the beaver is now being re-introduced throughout Europe. Several thousands live on the Elbe, the Rhone and in parts of Scandinavia. In northeast Poland there is a thriving community of Castor fiber.

They have been reintroduced in Bavaria and The Netherlands and are tending to spread to new locations. The beaver finally became extinct in Great Britain in

the sixteenth century: Giraldus Cambrensis reported in 1188 (Itinerarium ii.iii) that it was to be found only in the Teifi in Wales and in one river in Scotland, though his observations are clearly first hand. In October 2005, six European beavers were re-introduced to Britain in Lower Mill Estate in Gloucestershire, and there are plans for re-introductions in Scotland and Wales.

The American Beaver (C. canadensis) is the national animal of Canada; it is depicted on the Canadian five-cent piece and was on the first Canadian postage stamp, the Three Penny Beaver. However, in several areas of that country, it is considered a pest. The American Beaver is also the state animal of Oregon, the state mammal of New York (after the historical emblem of New Netherland) and the mascot of Oregon State University.

It is also a common school emblem for engineering schools, including the California Institute of Technology and the Massachusetts Institute of Technology. It is also an emblem for London School of Economics and the name of its student newspaper - The Beaver.

The extinct North American Giant beaver (Castoroides ohioensis) was one of largest rodents that ever evolved. It disappeared, with other large mammals in the Holocene extinction event, about 10,000 years ago.

The habitat of the beaver is the riparian zone inclusive of stream bed. The habit of the beaver for hundreds of thousands of years in the Northern Hemisphere has been to keep these watery systems healthy and in good repair, although to a human observer, seeing all of the downed trees, it might sometimes seem that the critters are doing just the opposite.

Beaver work as a keystone species in an ecosystem by creating wetlands that are utilized by many other species. The ability of beavers to radically alter landscape is amazing. Next to humans, no other extant animal does more to shape its landscape. Introduced to an area without its natural predators, as in Tierra del Fuego, beavers have flooded thousands of acres of land and are considered an unstoppable plague.

Dams

The dams are created both as a protection against predators, e.g., coyotes, wolves and bears, and to provide easy access to food during winter. It is both the sound of water in motion and the current that stimulates the beavers to build. If, for example, a pipe is placed under the dam to drain it the beavers may stuff it with a tree trunk unless the pipe inlet is protected with a large cage-like filter.

They may repair any damage to the dam and build it higher as long as the sound continues. However, in times of high water, they often allow spillways in the dam to flow freely. Beavers have even attempted to build dams in response to recordings of water flowing even in the absence of water.

Destroying a beaver dam without removing the beavers takes a lot of effort, especially if the dam is downstream of an active lodge. Beavers can rebuild such primary dams overnight, but may not defend secondary dams as vigorously.

Recent studies involving beaver habitual activities have indicated that beavers may respond to an array of stimuli, not just the sound of running water. In two experiments Wilson (1971) and Richard (1967, 1980) demonstrate that although beavers will pile material close to a loudspeaker emitting sounds of water running, they only do so after a considerable period of time.

Additionally the beavers, when faced with a pipe allowing water to pass through their dam, eventually stopped the flow of water by plugging the pipe with mud and sticks. The beavers were observed to do this even when the pipe extended several meters upstream and near the bottom of the stream and thus produced no sound of running water.

Beaver dams can be disruptive; the flooding can cause extensive property damage, and when the flooding occurs next to a railroad roadbed, it can cause derailments by washing-out under the tracks, or when a beaver dam bursts and the resulting flash flood overwhelms a culvert. This disruption is not limited to human geography; beavers can destroy nesting habitat for endangered species, and often destroy mature trees for which they have no use.

Yet dam building activity restores wetlands, the land's most beneficial ecosystem. Such wetland benefits include flood control downstream, biodiversity (by providing habitat for many rare as well as common species), and water cleansing, both by the breakdown of toxins such as pesticides and the retention of silt by beaver dams. The latter also reduces erosion as well as decreasing turbidity that is the limiting factor for aquatic life.

Beavers have been known to build very large dams,the largest known was discovered near Three Forks, Montana and was 2,140 feet long, 14 feet high, and 23 feet thick at the base. When objectionable beaver flooding occurs, modern water level control devices can be installed for a cost-effective and environmentally sound solution. Unwanted damage to trees can be prevented by wrapping chicken wire or sheet metal around the base of trees.

Lodges

The ponds created by well-maintained dams help isolate the beavers' home, their lodge, which is also created from severed branches and mud. The lodge has underwater entrances to make entry nearly impossible for any other animal (however, muskrats have been seen living inside beaver lodges with the beavers who made it). A very small amount of the lodge is actually used as a living area.

Contrary to popular belief, beavers actually dig out their den with an underwater entrance after they finish building the dam and lodge structure. There are typically two dens within the lodge, one for drying off after exiting the water, and another, drier one where the family actually lives.

Danger signal

When startled or frightened, a swimming beaver will rapidly dive while forcefully slapping the water with its broad tail. This creates a loud 'slap', audible over large distances above and below water. This noise serves as a warning to other beavers in the area. Once a beaver has made this danger signal, all nearby beavers will dive and may not reemerge for some time.

Fur trade

Beaver pelts were used for barter by Native Americans in the 17th century to gain European goods. They were then shipped back to Great Britain and France where they were made into clothing items. Widespread hunting and trapping of beavers led to their endangerment.

Eventually, the fur trade fell apart due to declining demand in Europe and the takeover of trapping grounds to support the growing agriculture sector. A small resurgence in beaver trapping has occurred in some areas where there is an over-population of beaver; trapping is only done when the fur is of value, and normally the remainder of the animal is also utilized as animal feed.

Pines are native to most of the Northern Hemisphere. In North America, they range from the Arctic south to Nicaragua and Hispaniola, with the highest diversity in Mexico and California. In Eurasia, they range from Portugal and Scotland east to the Russian Far East, Japan, and the Philippines, and south to northernmost Africa, the Himalaya

and Southeast Asia, with one species (Sumatran Pine) just crossing the Equator in Sumatra. Pines are also extensively planted in many parts of the Southern Hemisphere.

Morphology

Pines are evergreen and resinous. The bark of most pines is thick and scaly, but some species have thin, flaking bark. The branches are produced in regular "pseudowhorls", actually a very tight spiral but appearing like a ring of branches arising from the same point.

Many pines are uninodal, producing just one such whorl of branches each year, from buds at the tip of the year's new shoot, but others are multinodal, producing two or more whorls of branches per year. The spiral growth of branches, needles and cone scales are arranged in Fibonacci number ratios.

The new spring shoots are sometimes called "candles"; they are light-colored and point upward at first, then later darken and spread outward. These "candles" offer foresters a means to evaluate fertility of the soil and/or vigour of the trees.

Pines are mostly monoecious, having the male and female cones on the same tree, though a few species are sub-dioecious with individuals predominantly, but not wholly, single-sex. The male cones are small, typically 1-5 cm long, and only present for a short period (usually in spring, though autumn in a few pines), falling as soon as they have shed their pollen.

The female cones take 1.5-3 years (depending on species) to mature after pollination, with actual fertilization delayed one year. At maturity the cones are 3-60 cm long. Each cone has numerous spirally arranged scales, with two seeds on each fertile scale; the scales at the base and tip of the cone are small and sterile, without seeds. The seeds are mostly small and winged, and are anemophilous (wind-dispersed), but some are larger and have only a vestigial wing, and are bird-dispersed (see below).

At maturity, the cones usually open to release the seeds, but in some of the bird-dispersed species (e.g. Whitebark Pine), the seeds are only released by the bird breaking the cones open. In others, the fire climax pines (e.g. Monterey Pine, Pond Pine), the seeds are stored in closed ("serotinous") cones for many years until a forest fire kills the parent tree; the cones are also opened by the heat and the stored seeds are then released in huge numbers to re-populate the burnt ground.

Pines grow well in acid soils, some also on calcareous soils; most require good soil drainage, preferring sandy soils, but a few, e.g. Lodgepole Pine, will tolerate poorly drained wet soils. A few are able to sprout after forest fires, e.g. Canary Island Pine. Some species of pines, e.g. Bishop Pine, need fire to regenerate and their populations slowly decline under fire suppression regimes.

Several species are adapted to extreme conditions imposed by elevation and latitude; see e.g. Siberian Dwarf Pine, Mountain Pine, Whitebark Pine and the bristlecone pines. The pinyon pines and a number of others, notably Turkish Pine, are particularly well adapted to growth in hot, dry semi-desert climates.

The seeds are commonly eaten by birds and squirrels. Some birds, notably the Spotted Nutcracker, Clark's Nutcracker and Pinyon Jay, are of importance in distributing pine seeds to new areas where they can grow. Pine needles are sometimes eaten by some Lepidoptera species (see list of Lepidoptera which feed on Pines) and also the Symphytan species Pine Sawfly.

Mosquitoes are believed to have evolved around 170 million years ago during the Jurassic era (206–135 million years ago) with the earliest known fossils from the

Cretaceous era (144–65 million years ago). They evolved in the land mass that is now South America, spreading initially to the northern continent Laurasia and re-entering the tropics from the north. Ancestral mosquitoes were about three times the size of the existant species and they are a sister group to the Chaoboridae (biting midges).

The family Culicidae belong to the order Diptera and contains about 3500 species in three subfamilies: Anophelinae (3 genera), the Culicinae (9 genera and >80% of all the species) and the Toxorhynchitinae (1 genus). The genera include Anopheles, Culex, Psorophora, Ochlerotatus, Aedes, Sabethes,

Wyeomyia, Culiseta, and Haemagoggus. Within the family Anophelinae six subgenera are recognized: Stethomyia, Lophopodomyia, Kerteszia, Nyssorhynchus (all South American), Cellia (Old World only) and Anopheles (worldwide).

Mosquitoes are principally nectar feeders with only the females requiring a meal of blood. In contrast to this rule the Toxorhynchites never drinks blood. This family includes the largest of the extant mosquitoes (colloquially referred to as "mosquito eaters") and their larvae are predatory on the larvae of other mosquitoes. Attempts have been made in the past to use these as mosquito control agents but with variable success.

In the English language, the word Mosquito (Span., little fly) dates back to 1583; The word was adopted to replace the term "biting flies" to prevent confusion with the house fly. It is derived from the word musca (Latin fly, cf. Skt maksh) and is related to the Italian moschetta and the French moustique.

The female mosquito (in almost all species) sucks the blood of mammals, including humans. Mosquito bites often swell up hours after happening, causing a red ringed white bump about a centimeter in diameter. This bump can itch for days and over-scratching the bite can cause it to bleed.

Mosquito bites can transmit diseases, such as malaria and West Nile Virus, so authorities in many areas take measures to reduce mosquito populations through pesticides or more organic means. An easy way to reduce mosquito populations in a residential area is the removal of standing water (where mosquitoes breed), and the use of repellents, such as DEET.