Have you ever heard of water bears? They have lived on the earth for more than 500 million years, long before dinosaurs. Though called "bears", they look completely different from bears! The largest ones are only 1. 4 mm long. Each of their eight legs ends with a claw（爪）. They also have sharp mouths! Some of the places they live may surprise you! They live deep down in the ocean. It's too dark to see well, and the weight of water from up above is very heavy. But tiny water bears can survive in such difficult environment. In space, there is no air, water or food. But water bears can live there! Astronauts took some water bears outside the space ship. Surprisingly, most of them lived. Some even laid eggs! The eggs even hatched （孵） into healthy babies!
There is no rain in dry valleys of Antarctica for two million years. But water bears can survive in such a place! How? First, they curl（蜷缩） into a ball. Then they do nothing. They can stay this way for more than 10 years! When they get wet again, they uncurl and start to move around. Sometimes wind or water moves them away when they curl up in a ball.
Besides the places mentioned above, water bears also live around us, but it's not easy to find them If we are careful and lucky enough, maybe we can find one.
