Living in water

Author: French Whiz Kids Association
Publisher:
Publish Date: 2003-01-01
Features: Living beings on Earth rely on breathing oxygen in the air to survive. Strangely enough, many animals and plants in freshwater or saltwater can also breathe oxygen. Aquatic organisms were the earliest forms of life. The evolution process from microorganisms to plants to animals took about 3 billion years in water. It wasn't until 400 million years ago that animals and plants began to conquer land. Later, after long evolution, some descendants of land-dwelling animals returned to aquatic life, but they could only breathe air like whales. Divers working underwater must carry oxygen tanks! Aquatic animals vary greatly in size and weight, just like terrestrial animals. They are busy hunting, communicating with their own kind, moving around, attacking, and defending themselves. Regarding their lives, we raise some basic questions: Why can these animals float and sink freely in water, or why isn't the surface their only habitat? Can they sleep in deep water? How do they find and capture prey? The answers to these questions will be found in the experiments in this book.