Years ago, as we know, zoos kept animals in cages. Cages made it easy for visitors to see the animals, but a small cage is not a good place for an animal to live in. Today animals live in open areas. There are usually plants and a little lake around, like the animals' habitats. Visitors usually stay in the bus to see the animals outside. Zoos help to protect all kinds of animals. They protect animals in the zoo as well as animals in the wild. How do they do this? Zoos tell people how animals live in the wild and how to help protect their environment. The number of many kinds of plants and animals is becoming smaller and smaller. Mammoths, which are related with Asia elephants, are now extinct(.Scientists say that 74 different kinds of living things are disappearing a day! Zoos are working together to help animals-our friends. A mammoth is a kind of   _   that has gone extinct.
plant bird animal tree