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 »

Although hermit crabs must keep their gills moist in order to be able to breathe, they cannot breathe underwater. In fact, they will die if they are submerged in water because their gills will not provide the oxygen they... More »

Some reptiles that live in caves include salamanders, snakes and frogs. These reptiles go to the caves to find a cool place to get away from the summer heat. Salamanders are a common reptile in U.S. caves, particularly i... More »

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Although hermit crabs must keep their gills moist in order to be able to breathe, they cannot breathe underwater. In fact, they will die if they are submerged in water because their gills will not provide the oxygen they... More »

Fish require oxygen for survival just like other animals, but they filter it from water using specialized organs called gills. A fish draws in oxygen-rich water and passes it through its gills. The organs absorb the oxyg... More »

Depending on the species, sea crabs eat plankton, worms, fish, shrimp and other crabs. Crabs that live in the deep sea survive on foodfalls, which are scraps of meat that fall to the ocean floor after being killed by ano... More »

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 »