Dolphins are mammals because they have all of the major characteristics of mammals; they breathe through lungs, they are warm-blooded, they produce milk for their offspring and they have hair. There is also evolutionary evidence that connects dolphins and whales to other mammals. read more
A mammal is a member of the class Mammalia. You can tell that a dolphin is a mammal because it has a number of characteristics that are only found in mammals rather than in fish, or any other kind of animal. read more
Fact #1: All mammals are united by having mammary glands that produce milk to feed their young. No other group of animals has this trait. In fact, the name “mammal” comes from having mammary glands. Fact #2: Dolphins have mammary glands that produce milk to feed their young. Conclusion: Dolphins are mammals. read more
Dolphins are a widely distributed and diverse group of aquatic mammals. They are an informal grouping within the order Cetacea, excluding whales and porpoises, so to zoologists the grouping is paraphyletic. read more