1 . Bats (蝙蝠) are the only flying mammals (哺乳动物) in the world. They can’t see very well. People think that all bats are blind. People often hear “as blind as a bat”. Bats have no trouble flying on the darkest nights and finding their ways around very well. How can bats fly and see at night? They fly by radar (雷达)!

Bats’ radar system works the same way as the one that ships and planes use. When bats fly through the air, they make a sound that is too high for our ears to hear. If the sound hits things, it comes back. Bats’ ears receive the messages. The messages can tell bats where the things are.

Bats go out to look for food at night. In the daytime they hang in some dark places. Some people treat the bats as bad animals. In fact, they are useful animals.

How do animals sleep? Most people think they sleep in the same way as us. In fact, the ways they sleep are much more different—they can lie down, sit or stand while they sleep.

Swiss scientists did a study on 250 different mammals (哺乳动物). They found that the animals’ sleeping postures (姿势) had something to do with their size and weight. Small animals with short legs sleep on their stomachs. Their body shape is perfect for this posture. They also like to put their legs under their bodies. Rabbits and cats sleep this way. But larger animals sleep differently. They lie on their sides. That’s because this is more comfortable for their longer legs. Cows and hippos often sleep like this.

However, there are exceptions. Small animals such as mice sometimes sit down to take a short nap. Some large animals such as horses, zebras and giraffes sleep standing up. Do you know? Albatrosses (信天翁) are large seabirds. They can sleep while flying. They can even do that while flying at a speed of about 40 km an hour.

5 . There are many different kinds of kangaroos (袋鼠). They live in Australia. The smallest kangaroos are about a quarter of a metre long. The biggest kangaroos are taller than a man.

Kangaroos have very long, strong back legs. These are used for jumping. They also have long, strong tails (尾巴). Kangaroos’ front legs are much shorter, and are almost like arms. Kangaroos’ heads are small, but their ears are quite large.

Mother kangaroos have a pocket at the front. They have one baby each year. When it is born, the baby kangaroo is straight (直接) into its mother’s pocket. The baby kangaroos stay there for six months.

The biggest kangaroos stand more than two metres tail, and their legs are so strong that they can jump more than nine metres. They are very fast, and can travel at more than 50 kilometres an hour. They are very strong, but only eat fruit, leaves and grass.

7 . Animals grow up in different ways. Some newborn animals are helpless but their mothers protect them. A newborn kangaroo is very small. It is only a few centimeters (厘米) long. It closes its eyes and doesn’t have hair. It stays safe in its mothers pouch (育儿袋) for a long time.

A newborn monkey cannot walk. Its mother carries it everywhere. Other baby animals can walk soon after they are born. They learn to run with their mothers when danger is near. A baby zebra can run an hour after it is born. Some baby animals are born in a place that is safe. Baby wolves (狼) are usually born in big holes with little light. Other baby animals are born in the open. A baby elephant is often born on the open land.

Animals that drink their mothers’ milk are called mammals. A mother bear’s milk is rich. Baby bears have milk for a few months. This is the same with baby zebras. As baby animals grow, they need solid (固体的) food. Baby lions catch what their mother can catch!

9 . Animals grow up in different ways. Some newborn animals are helpless but their mothers protect them. A newborn kangaroo is very small. It is only a few centimeters long.

It closes its eyes and doesn’t have hair. It stays safe in its mother’s pouch（育儿袋）for a long time. A newborn monkey can’t walk. Its mother carries it everywhere.

Other baby animals can walk soon after they’re born. They learn to run with their mothers when danger is near. A baby zebra can run an hour after it is born.

Some baby animals are born in a place that is safe. Baby wolves are usually born in big holes with little light. Other baby animals are born in the open. A baby elephant is often born on open land.

Animals that drink their mothers’ milk are called mammals（哺乳动物）. A mother bear’s milk is rich. Baby bears have milk for a few months. This is the same with baby zebras. As baby animals grow, they need solid（固体）food. Baby lions eat what their mother can catch.