Fish have gills because these organs are used to extract oxygen from the surrounding water in which a fish lives. Gills are different from lungs because gills generally work unidirectionally: water moves in one direction... More »

The function of a fish's gill rakers is to strain and retain food particles. Gill rakers are a set of tooth-like processes present on the inner side of the gill arch in most bony fish. More » Pets & Animals Marine Life Fish

Fish gills act as the equivalent of a mammal's lungs by taking in oxygen and releasing carbon dioxide. Oxygen and carbon dioxide travel across small, thin-walled blood vessels in both lungs and gills. In terms of evoluti... More » Pets & Animals Marine Life Fish

Fish use their gills to breathe by extracting oxygen from the surrounding water. The oxygen that fish and other animals with gills use is bonded to hydrogen molecules and is dissolved in the water. Water molecules are co... More »

Fish live in the water and breathe by absorbing oxygen through their gills. Fish are cold-blooded animals, so their internal body temperature is influenced by the environment. Many fish have scales and use their fins to ... More »

A fish breathes through its gills, extracting oxygen from the water. Other sea animals, such as whales, breathe oxygen from the air because they are mammals. More »

The vast majority of crabs have gills, much like fish, which extract oxygen dissolved in water. Even when they are on land, the gills can still absorb oxygen as long as they are kept moist. There is also a small selectio... More »