• Whales are mammals.

• All mammals share some features.

• Whales belong to a group of mammals called the

Cetacean.

• Cetaceans have two features that other mammals

don’t have.

• Cetaceans are split into four groups.

No

Cetacean group Baleen plates? Teeth? Echo-location?

Baleen

Sperm

Other toothed

Beaked

Yes

No

No

No

Teeth in lower jaw only

Many teeth

Few teeth

No

Yes

Yes

Yes

• From the evidence so far, baleen whales are more

different.

• There are 11 species of baleen whale.

• They include blue whales and sperm whales.

Q5, Q6• But in the 1990s new

evidence was found.

• Scientists looked at

DNA from 16 species

of cetaceans.

• The DNA showed

that:

- Sperm whales

were more closely

related to baleen

whales than other

groups.

- Beaked whales are

only distantly

related to any of the

other groups.