Aquatic animals are animals that live in waters similar to seas, oceans, rivers, lakes and reservoirs. For this purpose, they have characteristics that instruct them to survive in special environmental conditions in water. These aquatic animals use different breathing strategies such as gills, in other words, pulmonary respiration in marine mammals, or skin diffusion respiration in Eels and other species.

Aquatic animals can be classified in different ways, for example by their habitat (marine or freshwater) or their ability to move. However, the most appropriate way to classify different aquatic species is according to the animal group. To which they belong. Aquatic animals are sponges, cnidarians, echinoderms, crustaceans, fish, most mollusks, amphibians, some insects, reptiles, poultry and mammals.