Orca whales are toothed whales. ©Getty Images

Orca whales are toothed whales. ©Getty Images

Orcas are toothed whales, and are the largest of the same toothed whale family as dolphins. Most whales are toothed whales. Toothed whales do not chew their food, but swallow it whole. Their teeth are for catching their prey.  

All whales are mammals.  Orcas  are found in all the world's oceans, and are very social, living in groups called pods.  It is believed that each pod has its own way of communicating, rather like having a slightly different language.

An orca breaching. ©Getty Images

An orca breaching. ©Getty Images

They are large animals, males growing to about up to 8 m long and about 5000 kg, and females growing to about 6 m long and about 4000 kg. They are very fast and powerful.

Killer whales

Orcas, also known as killer whales,  are the largest of any predators of mammals - they feed on marine mammals such as walruses, seals and even the calves of other whales.  They also feed on fish, squid and marine birds.  Orcas hunt in packs,  and use tactics such as changing leaders during a chase so that they don't tire as quickly as the animal they are chasing. They have been seen attacking seals in shallow water, sometimes even landing themselves on the beach to get them. They sometimes slap the water with their tails to make a wave that washes prey such as penguins or sea lions off ice and into the water in order to catch them.

Whales sometimes pop their heads out of the water to look around. It is called 'spy hop'. ©Getty Images

Whales sometimes pop their heads out of the water to look around. It is called 'spy hop'. ©Getty Images

The body

Orcas have sleek streamlined bodies, tapered at both ends. They are easily identified with their striking black and white skin. They have a black dorsal fin and pectoral flippers. The dorsal fin helps keep them stable as they swim at high speed. Each orca's dorsal fin looks slightly different, and many are slightly bent for reasons that are unknown. Orca's bodies are dark on top and white underneath. This coloration helps them hunt because they are camouflaged when viewed from above or below.