Back to AnimalsDolphins are some of the most playful and intelligent animals on our planet. Even though dolphins spend their lives in the water, they are not fish, but are mammals. Dolphins can't breathe water like fish, but need to come to the surface to breath air. There are many kinds of dolphins. Perhaps the most famous are the Bottlenose Dolphin and the Killer Whale (that's right the Orca, or Killer Whale, is a member of the dolphin family).