Are whales mammals?

All whales are mammals. Whales, along with dolphins and porpoises, are cetaceans, meaning that they are part of the order Cetacea, one of the taxonomic branches of marine mammals.

Like all other mammals, whales give birth to live young and feed them with self-produced milk. They are warm-blooded, producing their own heat from consumed food. Some hair usually grows around whales' blowholes, but the rest of their bodies is typically smooth skin. Beneath a whale's skin resides a layer of fat called blubber that acts as an energy reserve and as insulation. Unlike fish, whales do not have gills; instead, they have lungs. They must surface occasionally to inhale through their blowholes.