There are roughly 35 species of dolphins and porpoises. The smallest is the vaquita, which is a delicate four feet long. Dolphins are mammals, like people. Although they live in the water, they breathe air. Although most dolphins live in the ocean, some live in rivers or even in lakes that are formed when part of a river is cut off.
Dolphins have ears, but they hear through their jaws.
Dolphins eat fish, squid and crustaceans like shrimp.