Is a dolphin a mammle

Yes, a dolphin is a mammal!

Even if the dolphin swims in the ocean, it is in fact a mammal, like whales.

Like other mammals, dolphins give live births (meaning their offspring is not hatched from eggs but alive and functional as soon as it exits the mother's body)

The mother dolphin also feeds its offspring milk, something that only mammals can do.

Finally, dolphins don't have gills like fish and must surface frequently to breathe the air.