Whales are divided into two main kinds – baleen and toothed. These two groups are broken into smaller and smaller groups until they get down to individual species.

Using terms such as ‘whales’, ‘dolphins’, and ‘porpoises’ can be misleading when people want a clear picture of how whales are related. The killer whale, for example, is actually the largest dolphin!

Scientists need to be accurate and consistent in their descriptions. That is why they use specific characteristics to classify life forms such as whales into related groups. This practice is known as taxonomy. It’s an essential tool in gaining a systematic picture of living things.

What's the difference?


People often use the term ‘whale’ to refer to the large animals in the group. These can be both baleen whales (the filter feeders) and toothed whales (which hunt single prey).


Dolphins usually have a beak and always have conical teeth that taper to a fine point.


Porpoises have no beak. Their teeth are flat and spade-shaped.

A comparison

Blue whale – Balaenoptera musculus

Blue whales are about 30 metres (98 feet) long – the largest animals to ever live. They are sleek swimming machines that move amazingly fast – sometimes called the greyhounds of the sea.

Sperm whale – Physeter macrocephalus

That big rectangular head is in fact the world’s largest nose! It’s also a massive sound generator. The sperm whale’s submarine shape is perfectly adapted for deep diving – it can swim down to 2000 metres (6500 feet). And it’s the largest toothed predator on earth.

Humpback whale – Megaptera novaeangliae

The first word of the humpback whale’s scientific name, Megaptera, means big wing. That’s because they have the longest flippers in the whale world – or the longest arms on the planet! Their flippers can grow to 6 metres (19 feet) long.

Pygmy right whale – Caperea marginata

The pygmy right whale is the smallest of the baleen whales. It has small flippers and a characteristic arched mouth. Very little is known about this species.

Gray’s beaked whale – Mesoplodon grayi

These torpedo-shaped whales have a prominent beak – the males grow a tusk-like tooth on either side of it. They have tiny flippers which tuck into little dents along their bodies.

Hector’s dolphin – Cephalorhynchus hectori

This is the world’s smallest dolphin at 1.5 metres (5 feet) long. There is one species, but two different types – Hector’s dolphin and Maui’s dolphin. Both are unique to New Zealand and can be identified by their rounded dorsal fin.

Diverse but rare and mysterious

Beaked whales are the largest family of whales after dolphins, yet little is known about them. They’re seldom seen at sea, and some species are known only from skeletal remains found on beaches. Te Papa holds the largest collection of beaked whales in the world.

The case of beaked whale skulls in the exhibition represents five groups in the beaked whales family. Most species of beaked whale belong to the genus Mesoplodon (meaning ‘armed with a tooth in the middle of the jaw’).

Some species appear very similar. One reliable method for defining individual species is to examine the shape and position of the tusk-like tooth. These teeth only erupt only in the males.