How did whales end up living in the ocean?

Have you ever wondered how whales - who are air-breathing mammals - ended up living in the ocean? Their evolution journey from land to sea is remarkable. We know whales are superbly adapted for underwater life….but where did they come from?

Modern whales are most closely related to hoofed mammals from a group called ungulates. This group includes giraffes, camels, deer, and hippos (the whales’ closest living relative).

Looking at a whale’s body and biology, there are plenty of clues to show that their ancestors were land mammals. For example, whales, like all mammals nurse their babies with their own milk. More clues are found in the whale’s skeleton – inside their front flippers they have arm, hand, and finger bones, and they still have hip bones which are left from a time when their ancestors had back legs.

Using the fossil record, we can track the whale’s evolution journey as they transformed into marine specialists. Scientists can recognise extinct whales from their unique earbones and skulls. There was a series of transitional whales who were amphibious (they could walk and swim) before the fully marine whales appeared.

Transitional whales had features of both land and marine mammals. Over time their front legs became flippers, their back legs shrunk, their tails became powerful for swimming, their nostrils became blowholes, and their eyes moved to the sides of their heads so they could see prey under the water.