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Science Lesson 3:
Life Science: Ecosystems
The world is made up of different biomes, which are different areas classified by the environment and the plant and animal life living there. There are five major biomes, each with their own characteristics. Much of what makes a biome unique is its relationship to water, whether it is plentiful or scarce.
Aquatic:
This is the most common biome, because water covers 75% of the earth. There are two kinds of aquatic biomes: freshwater and saltwater.
Freshwater biomes are inland ponds and rivers that do not contain much salt. Animals and plants that adapt to freshwater environments cannot live in high salt environments. These biomes usually have a limited number of aquatic species, because they may or may not be connected to other bodies of water.
In freshwater biomes, you will find fish, plankton, algae, insects, frogs, toads, lizards, and other aquatic life. Wetlands such as swamps have many trees and plants, but also a great deal of standing water. Different kinds of plant life exist in wetlands, such as pond lilies and cattails. Ponds, rivers, and wetlands are also home to many birds, such as ducks and geese, and mammals such as otters and beavers.
Saltwater regions include most oceans and a few inland bodies of water such as the Dead Sea and the Great Salt Lake. The oceans contain a wide variety of animal life, from the very small plankton and krill, through crustaceans and fish, all the way to huge creatures such as sharks and whales. These animals have adapted for a high salt environment and so cannot survive in freshwater environments.
Such environments also include a variety of plant life from algae to seaweed and kelp. Coral reefs are also found in warm shallow waters, often close to the shore of continents, such as Australia. Corals contain elements of both plant and animal life.
Because the oceans are very deep, there are different layers of ecosystems at various depths, each containing different kinds of plants and animals.
Desert:
The desert biome is marked with having very little rainfall, less than 50 cm/year. Deserts cover about a fifth of the earth’s surface in areas such as north Africa, the southwestern U.S., Mexico and Australia. Most deserts occur at low altitudes and high temperatures, though some deserts such as those in Nevada in Utah that are cold deserts. The driest place on earth is also the coldest in Antarctica.
The plants and animals who live in the desert have adapted to survive on little water. Plants include grasses and cacti, and animals include reptiles, small birds, arachnids, and small mammals such as mice, rabbits, and foxes that can survive on little water. Many animals take shelter during the day and come out to hunt or gather food at night when things are cooler.
Many deserts experience wide swings in temperature between day and night, with high daytime temperatures and low temperatures at night.
Forest:
Forests are a biome that contain dense concentrations of trees and plants. Today, forests occupy about a third of the world’s area, though it was formerly much more. Many forested areas have been reduced by mankind.
There are three major types of forests, including tropical forests, temperate forests and boreal forests.
Tropical forests or jungles occur near the equator. They are warm throughout the year, and do not have winter, but instead have the “rainy season” and the “dry season”. These forests always get around 12 hours of sunlight every day. These forests receive a great deal of rainfall as well, leading to an environment that supports a variety of plant and animal life. There are thousands of species of plants and animals that live in these forests.
Plans include ferns, orchids, vines, mosses and palm trees in addition to hundreds of kinds of trees. Animals include tropical birds such as parrots and toucans, bats, small mammals, insects and larger predators such as jaguars and large snakes.
Temperate forests occur farther away from the equator in North America, Asia and Europe. They have a more moderate climate in temperature and rainfall than in forests. Some forests contain mostly deciduous trees, which are those who lose their leaves in the fall and regain them in the spring. Others have evergreen trees, such as pine trees that never lose their leaves.
Animals include bears, foxes, deer, mountain lions, rabbits, birds, squirrels, wolves and others.
Boreal forests, also called taiga are forests that are the farthest away from the equator found in Canada, northern Europe and Asia, Alaska and other places. They have relatively warm summers and long, dry, cold winters. Most of the moisture falls as snow, and most of the trees are evergreen trees.
Animals include moose, bears, foxes, wolves, deer, bats and hawks.
Grassland:
The grassland biome is characterized by land that is covered with grasses and shrubs rather than trees. There are two different kinds of grasslands: tropical grasslands or savannas, and temperate grasslands.
Savannas cover much of the surface of Africa, Australia, South America and India, and are tropical grasslands covered by individual trees. They have warm climate with a rainy season and a dry season like a jungle. The dry season causes naturally-occurring fires, which actually help maintain the balance of the savanna.
Animals on the savanna include giraffes, kangaroos, mice, snakes, lions, beetles, zebras, buffaloes, leopards, hyenas and elephants.
Temperate grasslands have almost no trees, but many grasses as small shrubs. Temperatures vary more from season to season than on the savanna, and there is less rainfall. This kind of grassland is found in the central U.S., parts of Russia, South Africa, and some areas of South America.
Animals you might find in a grassland include foxes, mice, deer, coyotes, grasshoppers, snakes, owls and badgers, among many more.
Tundra:
The tundra is the coldest of all biomes and has low precipitation. The plants and animals who live here are mostly simple because the conditions are so harsh. There are two kinds of tundra: the arctic tundra and the alpine tundra.
Arctic tundra is found in and around the North Pole. It has cold, desert-like conditions. A layer of the soil is permanently frozen, which is caused permafrost. Thus, the soil here does not drain away water well. There are no plants with deep root systems, but there are still many lichens, mosses, shrubs and grasses. Animals that exist there include lemmings, hares, squirrels, caribou, polar bears, migratory birds, and insects.
These are animals that have adapted to be able to survive during long winters, some of which hibernate through them, such as bears. Others migrate south when the weather is cold, such as birds.
Alpine tundra is found all over the world on mountains, where the cold climate is caused by high elevation. The soil here is well drained, which allows for other kinds of trees and plant life. The animals you might find here are mountain goats, sheep, elk, grouse, and a variety of insects.
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