Orca (killer whale)

Orcas (Orcinus orca), often referred to as "killer whales", are actually the largest member of the dolphin (Delphinidae) family. With between 48 and 52 large, conical shaped teeth, orcas are the top predators in the oceans.

They are black with white patches usually over the eyes, under the jaw, on the belly, and extending onto their sides. Female orcas can grow to 7.9m with a 0.9m dorsal fin, and males can reach 8.5m with a 1.3m dorsal fin.

Orcas can be distinguished from one another by studying their dorsal fins: shape, size, scars, nicks and marks on the fins and distinctive greyish-white saddle patches behind them all help identify individuals.

Where are they found?
Orcas can be found in all oceans, but they seem to prefer cooler, coastal waters. They are social animals and live in stable family groups called pods. Calves live and travel with their mothers even after they are fully-grown. Other members of the pod also care for the calves.

Each pod has its own "language", distinct from other pods by the "dialect" of sounds the pod uses. Orcas can easily recognize their own pod from several miles away based on their dialect.

What do they eat?
Orcas are often compared to wolves because both species are top predators, maintain complex social relationships, and hunt cooperatively as a pod. The orca diet consists of fish, squid, seals, sea lions and other whales and dolphins, and even sharks. Resident pods prefer fish whereas transient pods appear to target other marine mammals as prey.

How long do they live?
Orca males reach breeding age when they are around 6.7m long while females can breed when they are about 4.9m long. Orcas breed all year around and calves are born about 2.4m long after a 17-month gestation period. Female orcas usually give birth every three to ten years, and can live to be about 50 to 80-years-old.

Conservation concerns
Orca populations are stable, however, they are threatened by the same environmental changes that affect other whales, including habitat loss, pollution, and declining fish stocks.