Whales themselves were never land animals, but
their ancestors were. The first mammals
(animals that give milk and have hair) lived on
land. Some of the species that evolved from these
first mammals were carnivores and hunted other
mammals. Some of these evolved into predators
that lived in water. Some of their descendants
became even more adapted to living in water.
There’s a good whale “family tree” at:
whale family tree.
One interesting thing to notice is that even the
whales that have no teeth are the descendant of
carnivores. Another interesting thing is that
whales are more closely related to hippos than to
other marine mammals, like seals, walruses, and
The ancestors of the whales are long gone, so
how do we know that some of them lived in land
and some lived in water? Scientists study the
skeletons (or fossils of the skeletons) of
animals. They look for clues like flippers
instead of paws. Another big clue is whether a
skull has nostrils on the nose, or whether the
nostrils are on the top of the head—a blowhole. No
land mammals have a blowhole.
Some mammals spend all of their lives in water,
some of them live in water most of the time, but
also spend time on land. Take a look at pictures
of seals and sea lions. How are they like whales?
How are they different? Remember that I said
that mammals have hair? Do whales have hair? Do
whale fetuses have hair before they are born?
If you are interested in questions like these,
you may want to study marine biology, anatomy, or
Thanks for asking,