Some animals and plants in our world are very common, like houseflies, cats or daisies. They are not in danger of dying out. Otherspecies are very rare. Sometimes only a few of them are left. Such species may disappear forever.
Ever since life on earth began, animals and plants have died out and new ones have appeared. Dinosaurs, for example, roamed the planet during the earth’s middle ages. 65 million years ago they disappeared forever.
Animals and plants need each other to survive. They keep the world of nature in balance. If a certain plant dies out some animals may become extinct too, because they depend on the plant for food.
Why species become extinct
Long ago, most animals and plants became extinct because of natural events, like earthquakes or volcano eruptions. Climatic changes, like the beginning of the Ice Age, also led to the disappearance of certain species. Today, plants and animals are in danger mostly because of human beings.
Some plants and animals can survive in many areas. When they move to other places they adapt to their new environment very quickly. Others can only live in certain areas. We call such a living place a habitat. If a habitat is destroyed the species cannot find any more food or a place to live, sleep or have babies. So it dies out.
Habitats can be destroyed in many ways. More and more people live in our world. They need more space to live in. Rainforests, grasslands and other parts of nature are cleared and people start to settle there. They take away the natural home of plants and animals.
Pollution can also kill off certain species. Acid rain from factories goes down in rivers and lakes and can poison fish there.
The most endangered areas are the tropical rainforests. More than 50 % of all animals and plants live there. Every day, thousands ofacres of rainforest are destroyed and many species become extinct every day.
Ever since man appeared on earth he has killed animals and gathered plants. They have been used for food, medicine, clothes and to make homes. Cheetahs, tigers and other wild cats have been killed for their skins. Whales have been hunted for centuries because of their oil and blubber.
Most animals today are protected by international law, but many, like the black rhinoceros and theAfrican elephant are hunted illegally. Some species, like wolves, have been killed by humans because they were seen as a danger to farm animals.
Sometimes native animals become endangered when a new species comes to live in a place. Foxes were brought to Australia to kill off rabbits, which were seen as a pest. But instead of killing rabbits, the foxes killed kangaroos and other marsupials of Australia.
Parasites belong to the greatest threats to plants and animals. Tiny organisms, bacteria and fungi can destroy trees, kill birds and fish.
