Dolphins have great vision, although they can only see limited colors. They live in the water, but they do not drink from it. Instead, they get any necessary moisture from the food they eat.
As mammals, dolphins need oxygen to live, are warm-blooded and give birth to live young like humans give birth to babies. Dolphins nurse their young with milk. Baby dolphins are born with fine hair found on other mammals, although they soon lose it. There are many species of dolphin, and each species boasts a different number of teeth. For instance, both the false killer whale and killer whale or orca have only 10 to 14 teeth on each side of their mouths, while the short-beaked common dolphin has 240 teeth.
Dolphins can see both above and below the water, and they have great night vision. When using their vision below water, a substance coats the dolphins' eyeballs in order to protect them from the salt. However, dolphins can only see shades of gray and the blue-green spectrum.
In order to communicate with each other, dolphins whistle and squeak and use body language. They can also locate food or other dolphins under water using echolocation or high-frequency sounds.