Coral reefs are one of the most ancient ecosystems. The first stages of coral reef evolution began 350 million years ago. For a long time, scientists believed that giant panda bears from China were more like raccoons than bears. Today, we know that giant pandas are really bears. Koala bears from Australia are not real bears.
Koalas belong to a group of animals called marsupials.
Marsupials have a pouch where they carry their young. Kangaroos are also marsupials. There are 18 different penguins species. Penguins can live for 20 years and they only live in the deep southern hemisphere. They cannot fly but are very nimble in the water.