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The whales sing, not because they have an answer, they sing because they have a song.
| There are five classes of vertebrate animals (those with backbones)--birds, reptiles, amphibians, fish, and mammals. Mammals, including humans, are warm-blooded, have hair, breathe air into lungs, give live birth, and nurse their young. Most mammals live on land, but some can fly (bats) and many live in the ocean. |