Orcas or killer whales (Orcinus orca) are odontocetes and the largest species of dolphins. They are easily recognisable with their striking black and white or cream markings and extremely long, tapered dorsal fins.
Adult male orcas can grow to over 9 metres long and weigh over 7.5 tonnes, while females can grow to 8 metres or longer and weigh up to 4 tonnes.
Orcas have 10 to 12 pairs of interlocking, powerful, conical teeth in both jaws. They are carnivorous and opportunistic hunters who feed on a wide range of species including:
- fish, such as salmon
- sea birds, including penguins
- pinnipeds, such as seals, sea lions and walruses
- other whales.
Orcas hunt in groups (pods) of 3 to 40 individuals using highly effective, cooperative hunting techniques, which is why they have the nickname ‘wolves of the sea’. Orcas are apex or top-level predators. That means they are at the top of the food chain with virtually no predators of their own. However this places them at risk of health effects from the marine pollutants and contaminants they absorb from the food they eat.
Orcas are highly social animals that live in small nuclear or extended family groups. They have a “cosmopolitan” distribution, which means they are found in many parts of the world.