What are orcas?

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 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, not fish.  

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.

A pod, or group, of orca whales swimming underwater. ©Getty

A pod, or group, of orca whales swimming underwater. ©Getty

Behaviours

Orcas are aggressive hunters, also known as killer whales. They  are the largest of any mammal predator - 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.  

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

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

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.

Like all whales, orcas sometimes leap their whole bodies out of the water and then land with a huge splash. This is called breaching. Whales also put their heads out of the water to look around, keeping their bodies vertical. This is called a spy hop.

Leaping out of the water is called breaching. ©Getty

Leaping out of the water is called breaching. ©Getty

Body and Appearance

Orcas are large animals. The males grow to up to 8 m long and weigh about 5000 kg, and females grow to about 6 m long and about 4000 kg.

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.

The underside of an orca’s flukes. ©Getty

The underside of an orca’s flukes. ©Getty

Orca bodies are dark on top and white underneath. This coloration helps them hunt because they are camouflaged when viewed from above or below. Even their tails, or flukes, are black on top and white underneath.