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Every plant and animal on earth depends on other living organisms to survive. How these
living things interact with the sun, air, water, and each other is called an ecosystem.
Inside an ecosystem, the organisms work together to establish a balance that allows all of
its members to thrive.
When we talk about biomes, we mean a large group of similar ecosystems. All areas in
a biome have similar plants, animals, and weather. There are many different biomes on
Planet Earth, both on land, and in the water.
Let's explore some of the many biomes on Planet Earth.
First, let's visit the Marine Biome.
The Marine Biome is made mostly of saltwater oceans and is the largest biome on Earth.
It covers about 70% of the Earth's surface and is home to more than 230,000 known species.
Animals that live in the marine biome include fish, sharks, octopus, seahorses, dolphins,
manatees, seals, and whales, among many others. The blue whale, believed to be the largest
animal that has ever lived on the earth, lives in the marine biome.
Thousands of plant species live in the oceans, too. Ocean plants are extremely important,
because they provide more than half of the oxygen on earth - that's more than every forest
in the world. Algae, kelp, seaweed, and even tiny phytoplankton all live and grow in the ocean.
There are many separate biomes within the ocean, based on changes to the temperature,
nutrients, and amount of sunlight in the water.
One special type of Marine biome is a Coral Reef.
Coral reefs are only small areas of the ocean, but about 25% of known marine species live
there. They are built up over thousands of years by tiny animals called 'polyps.' The
polyps have a limestone skeleton, and as one generation of polyps die, the next generation
grows on top of them, making the coral reef gradually bigger and bigger.
Polyps depend on energy from algae that lives inside of them to survive. Since algae is
a plant, they need sunlight to create food. That is why coral reefs are only found in
warm, sunny water.
Reefs provide food and shelter for many species, but they are vulnerable to destruction by
pollution and overfishing by humans.
The last type of aquatic biome we will visit is the Freshwater Biome.
Unlike the marine biome, which is filled with salt water, freshwater biomes are filled with
water that has very low levels of salt. For the most part, animals that can survive in
salt water cannot survive in freshwater, and animals that can survive in freshwater cannot
survive in salt water.
Animals that live in or around freshwater biomes include fish, frogs, alligators, snakes,
otters, turtles, and beavers.
There are three main types of freshwater biomes. They are ponds and lakes - which have still
water - streams and rivers - which have moving water, and wetlands - which are a combination
of land and water.
Let's move on to land biomes.
First we're going to visit the Polar Regions.
The polar ice caps in the arctic and antarctic are harsh places to live. Plants cannot grow
on the ice, so most life in this biome is animal. By living at the edges of the ice
caps, the animals that survive there are able to find food in the ocean - fish, mostly,
or smaller animals.
The south pole is mostly populated by penguins.
Sea birds like albatrosses, petrels, and gulls, may also nest or visit there, and whales and
seals thrive in the waters off the coast.
At the north pole, you might find polar bears, as well as water-going mammals like seals,
walruses, and whales. Their thick layers of fur or fat help to insulate them against the
freezing cold.
South of the Arctic lies the Tundra.
The tundra is cold, an average of only 18 degrees F or negative 7 degrees celcius. There
are only two seasons here: a long, dark winter, and a short summer. Because it is so close
to the North Pole, during the winter the nights become longer and longer until the sun doesn't
rise at all. The situation is reversed in the summer: days become longer, until the
sun stays up all day and all night.
Beneath a thin layer of top soil, the ground is permanently frozen, even during the summer
when temperatures may reach 50 degrees F or 10 degrees celcius. This is called 'permafrost.'
There are few nutrients here to sustain plants or animals. There are no trees: the growing
season is too short. Plant life in the tundra consists of moss and grasses, or small shrubs.
There are still animals to be found in the tundra. Arctic foxes and hares, snowy owls,
musk ox, and caribou are just some of the animals that live there.
Still farther south lie the forests.
At colder latitudes, forests are dominated by evergreen trees. By keeping their needles
all year round, they are able to make the most of the weaker sunlight. Farther south
the pine trees mix with broadleaf trees that drop their leaves when the weather turns cold.
Forests grow where it is not too hot, and not too cold; places with lots of nutrients
and water available. As a result, a wide variety of plants and animals make forests their home.
Moose, deer, bears, wolves, foxes, rabbits, and squirrels, as well as many, many kinds
of birds and reptiles make their homes in forested biomes.
Another type of biome is Grassland and Savanna.
Grasslands are wide open land with low growing plants like grass and flowers. There is not
enough rain in a grassland to support tall trees, but too much water to be a desert.
A savanna is very similar to a grassland, but it may also have scattered trees.
Many different types of grasses grow on grasslands and savannas, and many large herbivores live
there. Often huge herds of grazing animals travel the grasslands together, seeking safety
in numbers from the predators that hunt them.
Although there are not many places for large animals to hide in the grass, there is plenty
of cover for small animals like mice, snakes, rabbits and birds.
In hotter climates we find the Tropical Rainforest.
Rainforests are forests that get a lot of rain, and tropical rainforests are very humid
and warm. Situated close to the equator, they stay warm year-round. Tropical rainforests
have the greatest biodiversity - that is, the greatest number of plant and animal species
- of any land biome in the world.
Trees in the rainforest usually grow to at least 100 feet or 30 meters in height, and
from the highest part of the canopy to the forest floor, tropical rainforests are teeming
with life. Some rainforest animals never touch the ground for their entire lives!
Small animals like monkeys, birds, snakes, frogs, and lizards are common in the rainforest.
Sloths, monkeys, bats, anteaters, jaguars, and thousands upon thousands of insects live
there, too.
The rainforest is an important producer of oxygen for the world, as well as a home for
about half of all the world's plant and animal species. Many new medicines have been found
because of research on plants that grow there. Tropical rainforests are so large and dense
that there are believed to be many unknown plant and animal species still to be discovered
there, but rainforests are threatened with destruction as humans cut them down for wood
and farmland.
The last biome we will visit today is the Desert.
Deserts are dry. Some are hot, and some are cold, but when most people think of deserts
they think of hot places.
Deserts in warm places may get very hot during the day, but because they are so dry, they
are not able to hold in the heat from the sun, and they may drop to below freezing at night.
Despite the harsh conditions, many plants and animals have learned how to survive in
the desert. Cactus are a very famous kind of desert plant, but grasses, shrubs, and
some kinds of small trees can grow there, too. Many kinds of desert plants - not just
cactus - have some kind of thorns or sharp spines to help protect them from hungry animals.
Many types of reptiles live in deserts: snakes, lizards, and tortoises. Birds like owls and
hawks and mammals like camels, foxes, and desert hares have all discovered ways to survive
and thrive in the desert, too.
I hope you enjoyed learning about biomes of the world today. Good-bye till next time!