My Science School

At the North and South Poles there are areas that are covered by thick layers of snow and ice all year round, but the two areas are very different. The Antarctic region, around the South Pole, has land far under the ice. The Arctic region, around the North Pole, is actually frozen sea. It is possible for a submarine to travel right under the North Pole. Because in Polar Regions the sea is warmer than the land or ice, the Arctic, with more sea, is not as cold as the Antarctic.

Antarctica, or the South Pole region, is a continent which is covered with an immense ice shelf. The Arctic region, however, is mainly located in the north polar ocean and includes several larger islands such as Greenland, Spitzbergen, Franz Josef Land, Severnaya Zemlya Wrangel Island, Bank Island, Victoria Island, Ellesmere Island and various others that all boarder countries like Russia, Canada, Alaska and Greenland. The north polar ocean is covered by year round ice caps that generally extend far south during the Arctic winter and are made up of around 16 million square kilometers of ice. Polar bears live solely in the Arctic areas, while penguins on the other hand, are found in the southern Antarctic regions. For that reason polar bears and penguins never cross paths.

Unlike Antarctica, the Arctic is not a continent which is the predominant different between the two polar regions. Under the massive ice cap of the Arctic lies the Arctic Ocean whose depths reach 15,000 feet below the surface. Often times the two polar regions are confused due to their having such similar names. The Arctic was discovered by Phoenician sailors years before the common era (CE). They named the newly discovered region after a polar star which guided them to the end of the earth. The star was called “Arktos” by the Greeks during this time which meant “land of the big bear”. Coincidentally, this title helps many people remember that polar bears are found in the Arctic rather than Antarctica. Also found in the Arctic region is the arctic fox, different species of seals and whales, puffins, fulmars, and other bird species.

Though the Arctic is obviously a very cold region, it is still much warmer than Antarctica in the South. Known as “the land of the midnight sun,” the Arctic is located in a landmass above 12 frozen feet of ice.

1. Penguins are only seen in Antarctica. There are no penguins in the Arctic. In the Antarctic, there are no land predators which also mean it’s a bit easier for penguins to survive. The waters, however, are a different story!

2. Polar bears only exist in the Arctic. These larger-than-life bears roam the North in search of prey and habitat.

3. Arguably the biggest difference between the two regions is that Antarctica is a continent surrounded by oceans, while the Arctic is an ocean surrounded by continents and countries —north America, Europe, and Asia.

4. Because they are on opposite sides of the world, the Arctic and the Antarctic do not share the same seasons. The Arctic enjoys winter from October through March, while Antarctica’s winter is from March through September.

5. The Arctic has a considerable flora— with some 900 flowering plants. The Antarctic has very little vegetation, mostly lichens and algae. There are only two flowering plans in Antarctica.

There are seasonal variations at the Poles, but these are much more noticeable in the Arctic than in the Antarctic. During the Arctic summer the sea ice begins to melt and break away in large icebergs. Although the area around the North Pole is always covered by ice, the snow melts around the edges of the Arctic Circle so that Arctic animals can browse on the sparse vegetation. One result of this is that some Arctic mammals, which need camouflage to keep them safe from predators, change the colour of their coats from white in the winter to brown in the summer months.

The Arctic region contains a wide range of landscapes; plains, mountains, some very large significant rivers and lakes, rolling hills, huge stretches of tundra and the edge of the largest biome in the world, the taiga. The ice in the Arctic Ocean is largely formed from the frozen sea and contained by the surrounding land masses. It contains a large proportion of multiyear sea-ice that is 3-4m (10-13 feet) thick with some much thicker ridges. Greenland has the largest ice cap in the Arctic (and second largest in the world after the Antarctic ice cap) other than this permanent ice is quite rare and relatively small in extent. Ice bergs form when the edges of the Greenland ice sheet reach the sea, most of the ice in the Arctic even in the summer is frozen sea ice.

The ice you are standing on is 1m to 3m (3-10ft) thick floating on the Arctic Ocean, it is made of frozen sea water with some snow on top, sea level is usually no more than 1m below your feet and the sea bed another 4,260m below that. The ice may be flat and smooth or rough, having been broken up and refrozen together again. The ice is moving at anywhere from a snails' pace to walking pace. You are about 730km from the nearest land at the northern tip of Greenland. Temperatures here are estimated from those measured elsewhere in the Arctic, as there are no structures or a settlement out on the ocean, the ice is too unreliable and unstable.

Antarctica is 98% covered in ice which means that away from coastal regions (and even including many coastal regions) the landscape is icy mountains, glaciers or smooth ice-sheet. There are no significant rivers and none that flow year round, lakes are small, rare and often permanently frozen over, there is very little land vegetation, and no grassland, shrubs or trees. There are small areas of tundra on the Antarctic Peninsula and larger expanses on a number of Antarctic and sub Antarctic islands (though nothing like the huge areas found in the Arctic).

The total surface area of Antarctica approximately doubles each winter as sea-ice forms around the coasts, in the summer this ice breaks up and drifts north mainly melting as it does so, Antarctic sea-ice is therefore mainly first year ice. The great ice sheets of Antarctica calve enormous ice bergs into the sea that are measured in square miles (sometimes hundreds or thousands of them), much of the ice in Antarctic waters especially in the summer is freshwater ice from glaciers and ice sheets.

The South Pole has the opposite to this with the sun at its highest around the 21st of December, midsummer to the North Poles midwinter. You are standing at an altitude of about 2,835m (9,300ft) on ice that is 2,700m (9,000ft) thick, it reaches down to rock which rises to just over 100m above sea level, this rock is pushed into the earth's mantle by the weight of the ice. Altitude sickness is a risk at the South Pole for new arrivals arriving by plane. The ice is made from accumulated snowfall that has built up because it never melts. The ice is moving towards the Weddell Sea in the west at about 10m (33ft) per year. You are about 1,300km from the nearest sea at the Bay of Whales. Temperatures have been measured at the South Pole since 1956 as there is a large research station there.

The Cacti of American deserts are probably the best known examples of these plants. They store water in their fat, fleshy stems, so that they can survive in times of very little rain. Their leaves are reduced to narrow spines, so that they have a very small surface area from which to give off water by evaporation.

The variety of beautiful and interesting succulents seems endless.  There are hundreds of types of succulents with fascinating shapes and colors.  Many desert succulents will live healthy lives much longer than humans.  Some of the best succulent plants also have medicinal uses topically and/or internally.

You can grow succulents from seeds.  They are also easy to propagate from the leaves and cuttings. They grow best when you use specially prepared soil for succulents.  With a little patience, you are almost guaranteed success in starting a new succulent plant.

A succulent is any plant that can store water in its roots, stems or leaves.  Succulents have at least part of their plant that seems over-sized, fleshy and thickened.  All cacti are succulents.  Many other plants are designated as succulents even though they are not cactus.  Most succulents originated in arid regions but there are some that come from rain forests and every other type of environment.

The Latin word translated into “succulent” is “sucus” which means sap or juice.  It is typical of most species of succulents to have a liquid juice or sap in its leaves or body.

The Encyclopedia Britannica describes succulents as; “Succulent, any plant with fleshy, thick tissues adapted to water storage. Some succulents (e.g., cacti) store water only in the stem and have no leaves or very small leaves, whereas others (e.g., agaves) store water mainly in the leaves. Most succulents have deep or broad root systems and are native to either deserts or regions that have a semiarid season.”

In desert regions all over the world, animals have developed similar ways to make the best use they can of the little water that is available. Some creatures stay in burrows underground during the heat of the day, only venturing out during the night, when it is cooler. Many desert animals do not have sweat glands, and their kidneys are able to remove most of the water from their urine. Several animals have ways of storing food as fat, for use when their normal food is scarce. As well as camels, these include lizards that have fat stores in their tails.

The desert is a huge, wide open space, meaning there isn’t much respite from the baking sun. For many desert animals, seeking shade is paramount to survival. Some animals cool off under the shade of a large cactus or rock. The Cape Ground Squirrel native to Africa uses its bushy tail as a parasol, bringing shade wherever it goes. Of course, there’s always shade to be found underground. Snakes, desert foxes, and skunks are just a few of the species of animals that burrow underground to avoid the hottest hours of the day.

When you’re tucked away in an underground burrow, the smartest thing to do is take a nap. Many burrowing desert animals are also nocturnal, meaning they sleep during the day and are active at night. The desert cools off significantly at night, allowing these critters to catch a break from the punishing heat.

Not all creatures shy away from the sunlight. Silver ants, a species of insect native to the Sahara Desert, have an incredible adaptation that keeps them cool even in the blazing sunlight of midday. These ants are covered in metallic hairs that not only lend the ants their distinctive metallic color, but also reflect the sunlight, preventing it from reaching the ants’ bodies.

Earth’s driest deserts get around half an inch of precipitation per year, in the form of condensed fog. Water is so scarce that most desert animals obtain water not by drinking it, but from food sources. Desert plants often contain a small amount of water, enough for these efficient animals to survive on. Desert birds and reptiles often get water by eating insects.

Once a desert animal has obtained a few drops of precious water, it’s important to make it last as long as possible. Many desert creatures have evolved to be able to store water in their bodies. A tiny amount of excess water can be used to cool off. Some species of desert birds can evaporate water from their mouths in order to cool themselves. Other animals, like Fennec Foxes, have huge ears that spread the excess heat out over a large surface area.

When all else fails, some desert animals simply hibernate during particularly hot and dry periods. These animals burrow into the ground, lying dormant until the temperature drops slightly, or water becomes available.

More than a third of the Earth’s land is covered by desert, but very little of it has the sandy appearance that we usually think of when deserts are mentioned. Most of the world’s deserts are barren, stony places.

Most of the world's surface is covered in water, in the form of oceans. The remaining landmass of Earth amounts to approximately 29 percent of the surface. Of this remaining 29 percent, deserts of all types constitute an estimated 33 percent, or one-third, of the Earth's total landmass. This large percentage is due in part to the vastness of the world's largest desert -- Antarctica.

Though sand dunes and cacti might immediately spring to mind when people think about deserts, the term "desert" is actually more inclusive and refers to a variety of different land types, from arid canyons to frigid polar plains. Deserts, which make up a large amount of the Earth's land mass, are home to a diverse collection of plants, animals and landforms.

Deserts are primarily defined by their dryness. A desert can be any land area that has an annual deficit of water -- that is, an area where more moisture evaporates than is taken in through any form of precipitation. In more concrete terms, a desert is commonly defined as any area that receives less than 254 millimeters (10 inches) of precipitation (in the form of snow or rain) in a given year.

Because the definition of a desert is so broad and focused on aridness, there are many different and varied types of deserts. In general, deserts may be hot, like the Sahara, or cold, like Antarctica. Beyond that, deserts may be broken into several more categories, depending on their geographic and physical features and how they form. For example, rain shadow deserts are formed when landforms like mountains interrupt cloud cover and prevent precipitation on the protected, or leeward, side of a mountain range.

Antarctica averages less than 5 centimeters (2 inches) of precipitation in the form of snow each year. The icy nature of Antarctica is due to the accumulation of snow, which, despite its small amount, still falls faster in most regions than it can evaporate due to frigid temperatures. This massive polar desert accounts for approximately 14.2 million square kilometers (5.5 million square miles) of the Earth's surface. The largest hot desert on Earth is Africa's Sahara desert, which makes up 8.6 million square kilometers (3.3 million square miles) of the planet's surface. This arid land receives an average of less than 25 millimeters (1 inch) of rain each year.

Camels are among the largest desert animals, but they are so well adapted to dry conditions that they have been domesticated for thousands of years by people living in desert areas. They are kept mainly as beasts of burden but are also eaten and used as racing animals! Camels’ feet are able to splay out to prevent them from sinking into loose sand. They are able to close their nostrils to keep out sand, and their eyes are also protected by long eyelashes. The fat in their humps is a food store. Camels very rarely sweat, so they are able to conserve the water in their bodies much more efficiently than human beings.

Desert adapted camels have evolved physiological adaptations that reduce the amount of water lost or are able to tolerate significant amounts of water loss [9]. Where green forage is available in mild climates, the camel may go several months without drinking. During the winter and cold seasons of the year camels can go without water for months. They do not even drink when offered water. Under very hot conditions, it may drink only every eight to ten days and lose up to 30 percent of its body weight through dehydration. When the mean temperature reach 30-35°C, camels can go 10-15 days without water but when the temperature exceeds 40°C, shorter periods between watering is necessary.

The digestive and urinary tracts are well specialized in water conservation. Cattle lose 20 to 40 liters of fluid daily through feces, whereas camels lose only 1.3 liters. This is one of the primary methods for resisting water deprivation in the desert. Fluid is absorbed in the end part of the intestines, where the small fecal balls are produced.

The rumen helps maintain water balance in two ways. First, the rumen of hydrated ungulates and the foregut of camels contain a large volume of water, approximately equal to 20% of body weight, and may buffer ungulates against short term water deprivation. During the first few days of dehydration, fluid contained in the rumen is used to maintain water balance of blood and body tissues and represents a large portion (50–70%) of the water lost during dehydration. Second, after dehydration in some species, the rumen plays a role in the prevention of hemolysis and osmotic tissue shock during rapid rehydration.

The kidney is an important organ involved in the removal of unwanted nitrogenous substances, excess water and relative maintenance of osmotic concentration of the blood. The camel’s kidneys play a major role in the process of conserving water through increasing the osmolality of urine. The kidney is characterized by a long loop of henle, and a well-developed medulla. During dehydration, the kidneys reduce water losses both by decreasing the glomerular filtration rate and by increasing the tubular re-absorption of water.

The long loops of henle, which are four to six times longer than in cattle, have the function of both concentrating urine and reducing its flow. A dehydrated camel urinates only drops of concentrated urine being shown by white stripes of salt crystals on the hind legs and tail. This concentrated urine not only serves to conserve water, but also allows camels to drink water which is more concentrated than sea water (above 3% NaCl), and to eat salty plants (halophytes) that would otherwise be toxic. Anti-diuretic hormone (ADH) is important in regulating the volume of urine excreted and its concentration. ADH is produced in the hypothalamus and is released into the blood stream in response to increased blood osmolarity. Larger release of ADH leads to a fast renal response that causes increased re-absorption of water. This leads to a smaller volume of more concentrated urine being excreted.

The body of camels can tolerate loss of water over 30% of body weight whereas most mammals die if they lose half of this value. Rehydration following a period of water deprivation is important for animal survival. A camel may drink more than one third of its body weight as it rehydrates. In terms of actual water intake reported 110 liters in 10 minutes. In other animals rehydration at these levels would lead to over hydration and possibly death. The camel is able to do this as large amounts of water can be stored for up to 24 hours in the gut to avoid a rapid dilution of the blood.

No plants or animals can survive if they have no water at all for a long period, but in the desert regions of the world many living things have adapted so that they can thrive with very little water. Deserts are places with very little rainfall, but they are not always hot. Some are very cold at night or in the winter. Animals and plants have to be able to deal with extreme temperatures as well as a lack of water.

On average, a human can only go for an average of three days without water depending on the climate because the human body loses a substantial amount of water through sweating, breathing, and excretion. Every drop of sweat, exhaled breath, and wet excrete increases the chances of death of any desert animal through dehydration. There are a few animals that can survive for years without drinking any water. Some of the popular examples include the desert tortoise, kangaroo rat, the thorny devil, water-holding frog, African lungfish, and desert spade-foot toads.

Kangaroo Rat

The kangaroo rat of North America is one of the most specialized animals living in the desert environments and can go for its entire life without water. The small rodent gets its name from is long hind legs (similar to the Australian Kangaroo) that enable it to leap long distances as they search for food and water. Some of the adaptations to the arid environment include large cheek pouches that are lined with fur as opposed to saliva which enables the rodent to carry seeds without losing much-needed moisture. Other adaptations, such as highly specialized kidneys with additional tubules, help them in the conservation of water in the body through the extraction of water from urine. The urine of a kangaroo rat is about five times as concentrated as human urine. The kangaroo rat has an oily coat and does not sweat which goes a long way in conserving water in the body. In addition to that, kangaroo rats feed on seeds that are safely hidden in burrows. The seeds once consumed are metabolized to yield energy and water.

Water Holding Frog

The water holding frog (Cyclorana platycephala) is commonly found in Australian desert areas and has truly unique adaptation mechanisms to the harsh arid environment. During wet seasons, the water holding frog lives like ordinary frogs and then burrow into the soil when dry conditions set in to escape the hostile conditions. The frog has the unique capacity to absorb significant amounts of water through its skin which is then stored in its bladder and body tissues. Once the frog burrows into the soil, it encloses itself in a cocoon made up of its skin to keep from losing water. While in this condition the frog feeds on its skin and can stay in this condition for several years.

Thorny Devil

The thorny devil (Moloch horridus), which is also commonly referred to as the thorny dragon, is typically found in desert areas in Central Australia. The thorny devil captures rainfall and dew during drier conditions through layered scales on its body that have a hinge which enables it to trap moisture and water droplets between the scales. The collected water is then transported under the skin to the mouth. The process is enabled by tongue movements that create the needed pressure to draw water to the back of the mouth.

The Desert Spadefoot Toad

The spadefoot toad (Scaphiopus couchi), which was recently discovered in the Colorado Desert, has some of the greatest adaptations to desert conditions. These animals have managed to survive in a few isolations such as the edge of dunes and dry washes due to their unique environmental conditions. Spadefoot toads living in the dunes burrow into the permanently wet layer in the sand and remain there for the whole dry period. Others bury themselves beneath dense vegetation. Adult toads retain several layers of partially shed skin which reduce moisture loss by forming semi-impermeable membranes and can remain in that condition for years. The high osmotic concentration greatly increases its ability to retain water and perhaps even extract moisture from damp conditions. These toads also exhibit an extremely accelerated growth rate. Their eggs take less than 48 hours to hatch, and within ten days the tadpoles develop legs. In less than three months, the young toads grow to half the adult size.

As in most other habitats, the colouring of animals in the rainforest is very varied. Some are brilliantly coloured, to attract mates or to warn predators that they are poisonous. Other creatures have green or dark colouring to camouflage them amongst the vegetation. This hides them from their enemies and enables them to creep up on their prey unseen.

Parrots, macaws, parakeets… these rain-bowed tropical birds put to shame the brown and gray birds that are so common in Illinois and Chicago. Even Chicago's brightest birds—cardinals, blue jays, gold finches—are vibrant, but single-colored. Why are bright and multi-colored birds so common in tropical rain forests, and nowhere to be found in temperate climates like Chicago? Do the changing seasons make bright birds sitting ducks in the winter? Do jungle birds eat bright berries and fruits instead of brown and black seeds? What gives?

We can eliminate one option right away: a parrot's color has nothing to do with its diet. While a flamingo gets its pink color from the food it eats (brine shrimp and blue-green algae) and a cardinal is red in part because of the seeds in its diet, a parrot's color is determined by its genes. The incredible colors of the blue-and-yellow macaw do not come from tropical mangoes and imported blueberries.

It must be some other quality of the tropics that creates brighter birds: is it the rainfall? The year-round high temperatures.

The truth is that tropical birds don't tend to be more colorful. Dr. Nicholas Friedman of the Okinawa Institute of Science and Technology explains, "If you look at birds in the tropics, there are a lot of colorful birds that stand out. But there are really more species in general there and there are just as many more of the little brown ones".

In other words, the tropics are much more diverse in general than temperate or dry climates. The rainfall and year-round high temperatures contribute to rainforests having many more animal and plant species than other places. Of these many more animal species, some are brightly colored birds, but there are even more species that are plainly colored. The birds that are exported from the rainforests for zoos or as pets are the brightest birds, and these are the tropical birds that we in Chicago are familiar with. This leads to the overall impression that birds from the rainforest are more colorful as a rule.

The many habitats to be found in rainforests can be thought of as layers. In real forests, of course, these layers overlap each other a good deal.

Emergent Layer

These giant trees thrust above the dense canopy layer and have huge mushroom-shaped crowns. These trees enjoy the greatest amount of sunlight but also must endure high temperatures, low humidity, and strong winds.

The emergent layer consists of the tallest trees, with umbrella-like branches poking through the mass of leaves below. In this layer live free-flying birds and bats, including birds of prey.

Canopy Layer

The broad, irregular crowns of these trees form a tight, continuous canopy 60 to 90 feet above the ground. The branches are often densely covered with other plants (epiphytes) and tied together with vines (lianas). The canopy is home to 90% of the organisms found in the rain forest; many seeking the brighter light in the treetops.

The tree canopy consists of the leaves of mature trees. Their tops spread out to reach as much of the light as possible. As well as birds and fruit bats, monkeys and squirrels live in this layer, feeding on the fruits, nuts and leaves of the trees in the canopy.

Understory

Receiving only 2-15% of the sunlight that falls on the canopy, understory is a dark place. It is relatively open and contains young trees and leafy herbaceous plants that tolerate low light. Many popular house plants come from this layer. Only along rivers and roadways and in tree-fall and cut areas are sunlight sufficient to allow growth to become thick and impenetrable. 

Very little light filters through the leaves of the canopy. In the mid-zone, creepers called lianas hang in great ropes among the trees. Here there are monkeys, squirrels, birds and bats again, but also some snakes and tree frogs.

Forest Floor

The forest floor receives less than 2% of the sunlight and consequently, little grows here except plants adapted to very low light. On the floor is a thin layer of fallen leaves, seeds, fruits, and branches that very quickly decomposes. Only a thin layer of decaying organic matter is found, unlike in temperate deciduous forests.

The forest floor is very dark. Larger mammals, such as deer, tapirs, elephants, jaguars and bush pigs, forage among the fallen leaves or prey on each other or smaller animals.

Rainforests are being cut down at an alarming rate for two main reasons. Both large commercial farming companies and individual families clear the forest to gain land to cultivate and graze animals, although the rainforest soil is not suitable for this use. Secondly, forests have been felled to supply tropical hardwoods for furniture-making and building. Woods such as mahogany have been highly prized in wealthy countries for hundreds of years.

More than half of Earth’s rain forests have already been lost due to the human demand for wood and arable land. Rain forests that once grew over 14 percent of the land on Earth now cover only about 6 percent. And if current deforestation rates continue, these critical habitats could disappear from the planet completely within the next hundred years.

The reasons for plundering rain forests are mainly economic. Wealthy nations drive demand for tropical timber, and cash-strapped governments often grant logging concessions at a fraction of the land’s true value. “Homesteader” policies also encourage citizens to clear-cut forests for farms. Sustainable logging and harvesting rather than clear-cutting are among the strategies key to halting rain forest loss.

• Logging interests cut down rain forest trees for timber used in flooring, furniture, and other items.


• Power plants and other industries cut and burn trees to generate electricity.


• The paper industry turns huge tracts of rain forest trees into pulp.


• The cattle industry uses slash-and-burn techniques to clear ranch land.


• Agricultural interests, particularly the soy industry, clear forests for cropland.


• Subsistence farmers’ slash-and-burn rain forest for firewood and to make room for crops and grazing lands.


• Mining operations clear forest to build roads and dig mines.


• Governments and industry clear-cut forests to make way for service and transit roads.


• Hydroelectric projects flood acres of rain forest.

Rainforests in different parts of the world often have similar species, but because they have developed separately for thousands of years, they each have their own characteristics. Both South American jaguars and African leopards have spotted skins that camouflage them in the dappled light of the forest floor. Like leopards, jaguars have rings of black spots on their coats, but they also have smaller spots within those rings.

Body structure: The jaguar is stockier and more muscular than the leopard, with a compact body, a broader head and powerful jaws.  The jaguar’s tail is also generally shorter than the leopard’s tail.

Fur pattern: Though jaguars and leopards both have coats that feature rosette patterns, a jaguar’s rosettes have spots inside them. Both jaguars and leopards can have either golden colored fur or appear black, which is called melanistic.

Body size: The leopard is considered the smallest of the four “big cats.” The other three are the tiger, lion, and jaguar.

Behavior: Jaguars and leopards can both swim very well.  Though jaguars love to spend time in the water, leopards will avoid it.

Jaguars are braver than leopards when it comes to facing off with another species that’s bigger.  Leopards tend to shy away at the sight of a bigger animal like a lion or hyena while jaguars will boldly stand their ground or even attack anaconda or large caimans in their native habitats.

Habitat range: In the wild, jaguars and leopards inhabit totally different continents. The jaguar once roamed from Argentina in South America all the way up to the Grand Canyon in Arizona.  Today, jaguars have been almost completely eliminated from the US and are endangered throughout their range, stretching down to Patagonia in South America.

On the other hand, leopards are found throughout most of Africa and Asia, from the Middle East to the Soviet Union, Korea, China, India, and Malaysia.

Strictly speaking, tropical rainforests should fall within the tropics — between the Tropic of Capricorn and the Tropic of Cancer. In fact, most are found even nearer to the equator. South America, Africa and Asia have large areas of rainforest.

CENTRAL AMERICA

This region was once entirely covered with rainforest, but large areas have been cleared for cattle ranching and for sugar cane plantations. Like other major rainforests, the jungles and mangrove swamps of Central America contain many plants and animals found nowhere else.  Central America is famous for its large number of tropical birds, including many kinds of parrots.

THE AMAZON

The Amazon jungle is the world's largest tropical rainforest.  The forest covers the basin of the Amazon, the world's second longest river. The Amazon is home to the greatest variety of plants and animals on Earth.  A 1/5 of all the world's plants and birds and about 1/10 of all mammal species are found there.

AFRICA

Central Africa holds the world's second largest rainforest.  To the south east, the large island of Madagascar was once intensively forested, but now much of it is gone. Africa contains areas of high cloud forest, mangrove swamps and flooded forests.  The island of Madagascar is home to many unique plants and animals not found anywhere else.

SOUTHERN ASIA

The rainforests of Asia stretch from India and Burma in the west to Malaysia and the islands of Java and Borneo in the east.  Bangladesh has the largest area of mangrove forests in the world. In Southeast Asia the climate is hot and humid all year round. In the mainland Asia it has a subtropical climate with torrential monsoon rains followed by a drier period.

AUSTRALASIA

Millions of years ago, Australia, New Zealand and the island of New Guinea formed part of a great forested southern continent, isolated from the rest of the world.   Today these countries contain many different species of animal that occur nowhere else. Undergrowth in Australia's tropical forests is dense and lush.  The forests lie in the path of wet winds blowing in from the Pacific.

Rainforests are tropical evergreen forests. They have at least 4000mm (156 inches) of rain each year. The climate is warm and moist all year round, giving conditions in which green plants can produce huge amounts of vegetation, flowers and fruit. There is always plenty to eat for insects and the animals that, in turn, feed on them. The rainforest also offers an extraordinarily wide range of habitats for living things.

Rainforests are areas of extremely high biodiversity compared to other ecosystems. In the rainforests of Borneo, scientists have documented more than 15,000 plant species, including 2,500 species of orchids! Biologists estimate that tropical rainforests contain about 50% of the world’s terrestrial plant and animal species, yet they encompass only about 6% of the world’s land area.

Rainforests have 170,000 of the world’s 250,000 known plant species. The United States has 81 species of frogs, while Madagascar, which is smaller than Texas, may have 500 species. An area of rainforest the size of two football fields (one hectare) may have more than 400 species of trees, while an equal area of forest in the United States may have fewer than 20. Europe has 570 butterfly species, while Manu National Park, a single reserve in Peru, has 1,300 species.

Because rainforests are located in tropical regions, they receive a lot of sunlight. The sunlight is converted to energy by plants through the process of photosynthesis. Since there is a lot of sunlight, there is a lot of energy in the rainforest. This energy is stored in plant vegetation, which is eaten by animals. The abundance of energy supports an abundance of plant and animal species.

The canopy structure of the rainforest provides an abundance of places for plants to grow and animals to live. The canopy offers sources of food, shelter, and hiding places, providing for interaction between different species. For example, there are plants in the canopy called bromeliads that store water in their leaves. Frogs and other animals use these pockets of water for hunting and laying their eggs. Many species in the rainforest, especially insects and fungi, have not even been discovered yet by scientists. Every year new species of mammals, birds, frogs, and reptiles are found in rainforests.

As grasslands usually have few trees or rocks to offer cover to smaller animals, many of them live in burrows underground. In North America, prairie dogs (Cynomys ludovicianus) live in huge numbers in connected burrows, sometimes causing the ground to cave in. The South American pampas also has many burrowing animals, including viscahas (Lagostomus maximus) and cavies (Cavia aperea), related to guinea pigs. The American bison, coyote, and gopher are just some of the animals that live in the grasslands.

Grasslands cover 25 percent of the world’s surface and it is the preferred habitat for animals like the wildebeest, coyote, and pronghorn. The grasslands provide animals with a variety of diets like grass, shrubs, twigs and even fellow animals for prey. The climate in the grasslands also changes depending on the seasons hence during the dry season, when water and grass are in short supply, animals move to other grasslands.

Swift Fox

Despite the resemblance to a domestic cat regarding size, the fox lives in near harsh conditions of North America especially in Colorado, New Mexico, Kansas, Oklahoma, and Arizona in grasslands. The survival of the fox in the grasslands is based on its omnivore diet of fruits and insects. Thanks to conservation efforts by wildlife authorities, the swift fox was saved from possible extinction. The lifespan ranges from 3-6 years in wild grasslands but in zoo, parks, and other forms of captivity, the swift fox can live for up to 14 years.

Prairie Dog

The structure of the prairie dog is similar to that of a squirrel, but it is their warning call to each other whenever danger lurks that sounds familiar to that of a dog. The grasslands are their preferred dwelling grounds because it provides them with hiding areas so they can protect themselves against harsh weather elements like floods and blizzards during the winter. The grasslands provide grass, seeds, and insects to prairie dogs. Predators do have a hard time trying to hunt the Prairie dog down thanks to the superior anti-predator techniques it has. If a predator is spotted, it employs an alarm response to alert fellow dogs.

Giant Anteater

Also known as the giant ant bear, the giant anteater feeds on ants, insects, and termites depending on the season of the grasslands. It tracks down its prey using scent. The giant anteater can be found in the grasslands of South and Central America. Predators like the puma or jaguar frequently hunt down this animal, but the giant anteater avoids them by galloping away. If cornered, it can use the hind legs, which are equipped with sharp claws to tear apart potential foes in defence. The mobility skills of this animal are remarkable as it can swim across rivers no matter the size. The climate changes cannot affect the animal due to its ability to adapt to cold weather and hot weather.

Gopher

The gopher is a rodent which uses tunnels as a means of protection and gathers food. Like other rodents, it has a small size and claws that are adapted to digging tunnels. Male gophers are slightly larger in size and weight than female gophers. The lifespan of gophers is five years and they can survive despite the threats from known predators like snakes. The gopher lives in the grasslands of Central America and South America.

Badger

Known for producing pelts which are used for making shaving belts, the badger is a sturdy animal that lives in the grasslands in North America. Determining the exact classification of the badger is not easy due to the existence of several species of badgers. However, the badger belongs to the Taxon Mephiditae family. In the past, badgers were hunted for their meat and hide, but due to conservation efforts they are no longer hunted today.

For most grazing animals, being part of a herd is their best defence against attack. Although individual animals, especially young, old or sick ones, may be picked off by predators, most animals will be safe. There are also more animals to watch out for danger while the rest graze. When attacked, the best defence of an antelope or zebra is its speed. At least over short distances, it can usually outrun its attackers. Wildebeest and some other heavier animals also have a powerful kick, which can break the bones of a lion or hyena if well aimed.

Defense mechanisms are very important to all animal life. Animals in every biome must eat to survive. With predators being high on the food chain and always on the lookout for a meal, prey must constantly avoid being eaten. Adaptations that prey employ ads to the chances of survival for the species. Some of these adaptations include defense mechanisms that can give prey an advantage against their enemies.

There are several ways animals avoid falling prey to a predator. One way is very direct and comes naturally. Imagine you are a rabbit and you have just noticed a fox preparing to attack. What would be your initial response? Right, you'd run. Animals can use speed as a very effective means of escaping predators. Remember, you can't eat what you can't catch!

Another defense mechanism is camouflage or protective coloration. One form, cryptic coloration, allows the animal to blend in with its environment and to mask its identity. Cryptic coloration is important to the survival of many new-born and young animals, as it is often their main defense against being detected by predators. Some animals blend in so well with their environment that it is very difficult to identify them. For example, some insects and other animals can look like leaves; both in their visual appearance and their behavior. It is important to note that predators also use cryptic coloration to avoid detection by unsuspecting prey.

When faced with danger, some animals pretend to be dead. This type of adaption is known as thanatosis. Opossums and snakes can even emit a fluid that produces a foul smell, thus adding to the pretense. Such behavior tricks predators into thinking that the animal is dead. Since most predators avoid dead or rotting animals, this type of defense mechanism is often very effective.

Some animals try to avoid predators by simply running, flying or swimming away as fast as they can. This is a very common defense mechanism that many animals use. Many animals that use speed as a defense live in open habitats, which don’t provide many places to hide from predators. Many animals that rely on speed also have excellent vision or hearing, so they can detect predators before they get very close.

To sum it all up, the predator-prey relationship is important to maintaining balance among different animal species. Adaptations that are beneficial to prey, such as physical defenses, ensure that the species will survive. At the same time, predators must undergo certain adaptive changes to make finding and capturing prey less difficult.

Without predators, certain species of prey would drive other species to extinction through competition. Without prey, there would be no predators. The animal organisms in such an environment could become endangered or even extinct. The predator-prey relationship ensures that the cycle of nutrients in biomes continues. Thus, this relationship is vital to the existence of life as we know it.