* Warm-blooded: They regulate their own body temperature.
* Give birth to live young: They don't lay eggs.
* Nurse their young: They produce milk to feed their babies.
* Have hair or fur: Though some whales have very little or no hair, they still have follicles and are descended from hairy ancestors.
* Breathe air: Though whales live in the ocean, they need to come to the surface to breathe air.
They also share some similarities in their social structures:
* Herd animals: All three species live in groups, often with complex social hierarchies.
* Communicate through sounds: They use a variety of vocalizations to communicate with each other.
While they may seem very different, whales, cattle, and elephants are all part of the same large and diverse family of mammals.