Aquatic animals include fish, shrimp, crabs, sea animals, etc., and aquatic plants include water onions, rudbeckia, water lilies, loosestrife, gorgonians, plantain, pike grass, etc. Aquatic animals mainly refers to the animals living in the water, and most of the aquatic animal species are basically in the process of species evolution has never been separated from the water life of animals, but there are also such as aquatic insects, whales, etc. by terrestrial animals transformed into aquatic animals aquatic animals.

Aquatic plants generally refer to plants that can grow in water, and the most important feature of these plants is that the gaps between the cells are more developed, and also has a special aeration organization, which ensures that the plant can have enough oxygen to grow when it is underwater.

In addition, aquatic plants have a large leaf area, but the development of the epidermis is weak, some plants in special circumstances almost no epidermis, and in the water when the leaves will gradually split into filaments or ribbons, which is used by aquatic plants to increase the area of carbon dioxide, light, inorganic salts absorption of the main means.