Skip to content

How did whales evolve?

Looking at a whale’s body and biology, there are plenty of clues that their ancestors lived on land. They breathe air and nurse their young with their own milk, they also have paddle-shaped flippers which encase hand bones with five ‘fingers’. As embryos, whales have tiny back limbs which disappear before birth.

Hippos are the closest living relatives of whales, but they are not the ancestors of whales. Both hippos and whales evolved from four-legged, even-toed, hoofed (ungulate) ancestors that lived on land about 50 million years ago. Modern-day ungulates include hippopotamus, giraffe, deer, pig and cow. Unlike the hippo’s ancestor, whale ancestors moved to the sea and evolved into swimming creatures over a period of about 8 million years.

Fossils of gigantic ancient whales called Basilosaurus were first mistaken for dinasaur fossils but were later recognised as mammals. These prehistoric whales were more elongated than modern whales and had small back legs and front flippers. Their nostrils were situated halfway between the tip of the snout and the forehead and they had earbones just like those of modern whales. Basilosaurus shows the link or intermediate between whales and their terrestrial ungulate ancestors.

The theory is that some land-living ungulates favoured munching on plants at the water’s edge which had the added advantage of allowing them to easily hide from danger in shallow water. Over time their descendants spent more and more time in the water and their bodies became adapted for swimming. Their front legs became flippers and a thick layer of fat called blubber replaced their fur coats to keep them warm and streamlined. Eventually, their tails became bigger and stronger for powerful swimming and their back legs shrunk. Gradually, their nostrils moved to the top of their heads so that they could breathe easily without the need to tilt their heads while swimming. As some of these creatures began to feed on a different diet, they evolved into baleen filter feeders and lost their teeth.

Amazing facts about whales and dolphins

Dive deeper into the world of whales and dolphins and learn more about their lives.

A humpback whale pokes its head partway out of the water, a behavior called spyhopping
two dolphins diving down out of the water
Northern Resident orca, Fife, swimming at the surface
Breaching North Atlantic right whale

Facts about whales

Amazing facts about whales, the largest mammals to live on Earth.

Facts about dolphins

From the orca to the tiny vaquita, learn more about these creatures.

Record breakers

Whales and dolphins hold some incredible records.

Brain power

Just how intelligent are whales and dolphins?

Make a difference

Join our team  - no matter which way you choose, your commitment helps whales, dolphins, and our shared planet.

Save the whales, save the world.

Humpback whale poking its head out of the water, a behavior called spyhopping

Adopt

Adopt a whale and help us protect these amazing creatures.

Bottlenose dolphin calf breaching with its whole body out of the water

Join

You can join our team and help us save whales and dolphins

Breaching North Atlantic right whale

Donate

Your gifts help us take action for whales and dolphins.

Orca spyhop

Shop

Support WDC by shopping for yourself or a friend.