Marine Mammals

Dugong / Dugong dugon / Family - Dugongidae

Mammals generally live on the land, however a few have made their homes in the sea.

Although marine mammals are beautifully suited to their life in the sea, they must all return to the surface at regular intervals to breathe. Many however, are completely free of the land and give birth to live young in the sea.

Whales, dolphins and dugongs are mammals that can be seen in the Great Barrier Reef area. Whales and dolphins are collectively referred to as cetaceans. There are about 80 species of cetaceans worldwide with about 27 species found in the waters of the Great Barrier Reef.

Cetaceans are divided into two groups: those with teeth and those without. Beaked whales, pilot whales and dolphins all have teeth. In fact, dolphins are really small-toothed whales. The largest toothed whale is a sperm whale.

In general, cetaceans over about six metres are called whales and anything smaller is referred to as a dolphin or porpoise. Exceptions are the pygmy sperm whale which only grows to 3.7 metres, and the killer whale (Orca) which belongs to the same group as dolphins.