Latin name: Orcinus orca

Killer Whale - Photo: Brendon Grunewald

Killer Whale – Photo: Brendon Grunewald

The Orca is found in all oceans and seas of the world, from the deepest waters to the coast. They occur less in waters furthest from land and those which are not as productive in the tropics and sub-tropics. The degree of ice cover limits their polar distribution, and they do not normally migrate from warm to cold waters like the baleen whales do – they seem sturdy enough to be able to survive in one or the other, or both.

Classification

The Orca was classified by Linnaeus in 1758, with the original name of Dephinus orca – ‘demon dolphin’. In 1860, however, a new genus was created, Orcinus, in recognition of the differences between this species and the smaller dolphins. Despite its size and common name, however, the Orca is, in fact, the largest dolphin, and is more closely related to them than to the ‘great’ whales. The False Killer Whale and Pygmy Killer Whale are quite separate species.

Local Names

Killer Whale; Orca Dolphin; Blackfish; Grampus; Great Killer Whale.

Description

The Orca is a well-known cetacean, made famous by captivity shows. It has a striking skin combination: the primary colour is black, but there is the addition of a grey ‘saddle’ behind the dorsal, and a brilliant white that covers three areas. Working back from the head, the first of these is the almost elliptical patch behind each eye. The second is on the underside of the jaw, extending back along the throat and belly to the flanks and vent area, where it forms a shape similar to the three prongs of a fork, two reaching up along the flanks while the third covers the vent area. The undersides of the tail flukes are also white. In some regions of the world the primary colour, black, is more of a dark grey. In males, the dorsal fin can reach up to 1.8m in height, and reaches straight up into the air, shaped rather like a triangle. In females the fin is smaller, about half the size, and more curved. The head is rounded, with an indistinct beak, inside of which are 10-12 pairs of large teeth in both the upper and lower jaws. This stocky species reaches a maximum length of 9.75m for males and 8.53m for females. The maximum body weights are 10.5 tonnes and 7.4 tonnes respectively.

Recognition at sea

The male Orca’s dorsal fin is a tell-tale giveaway, being as tall as a man and shaped like a huge triangle. The blow is low and bushy, and they travel in pods of between three and twenty-five individuals, including at least one large male.

Habitat

Orcas occur from the polar regions to the equator, and are often found among ice floes. They can adapt to almost any conditions, and appear to be at home in both open sea and coastal waters. Occasionally they may enter estuaries, but when they do, they never stray far from the sea.

Food & Feeding

Known as the ‘Wolves of the Sea’, Orcas are fearsome predators. They have the most varied diet of all cetaceans, and can tackle prey of all shapes and sizes. Their co-ordinated hunting strategies – working as a team and not as individual units within the pod, akin to a pack of wolves – show their intellegence and cunning. Hunting in this fashion increases the yield of prey per individual, so that none go without. In some areas of the world, one Orca will hunt but shares the catch with the other members of its pod. Hunting normally occurs during dives of less than 100m, with members of the pod co-operating in keeping the prey at or near the surface. Known prey include a variety of both warm and cold-blooded creatures – at least five species of seals, the dugong, thirty species of fish, turtles, some two species of squid, seven species of seabird, and at least twenty-four species of cetacean, including the massive Blue Whale.

Behaviour

The typical family pod can reach a maximum of around fifty individuals, but most often numbers between 3-25. From behavioural studies in Canada, there are two types of pod recognised: residents and transients. Transients form smaller pods of between 1-7 individuals, roaming over a larger area and feeding mainly on mammals. They vocalise less frequently, often change direction abruptly when swimming, and remain underwater for up to fifteen minutes at a time. Residents, on the other hand, form larger pods, have smaller home ranges, and feed mainly on fish. They vocalise frequently, keep to predictable routes, and rarely stay underwater for more than four minutes. Both transients and residents are acrobatic at the water’s surface; breaches, spy hops, and tail slaps are common, and there is little aggression within a pod. Mass strandings are rare, but have been known to occur. Studies have also shown that there are differences in vocalizations between pods. It seems each pod (or communities of pod, such as superpods where more than two pods congregate) has its own dialect, and this changes from pod to pod. Cetologists working in Canadian waters can now tell which pod is nearby simply by the differences in vocalizations. The degree of difference between pods’ dialects reflect the degree of social interaction between the pods – for instance, if two pods’ vocalizations are very similiar, then they interact with each other, maybe coming together as a superpod.

Longevity

Between 25-90 years, with females having a longer lifespan.

Estimated Current Population

Unknown, but locally common.

The Influence of Man

Orcas are normally a secondary target for whalers, although catches for meat and oil have been considerable in some areas. Norway, Japan and Russia took a combined total of 5,537 Orcas between 1938-81, with 916 of those killed in the 1979-80 whaling season. Greenland takes 2-3 every year. The other ‘market’ for Orcas concerns the live capture for public display, the most famous of which is probably Sea World. These cetaceans were taken mostly from the north-eastern Pacific Ocean (67 between 1962-73) and from Icelandic waters (84 between 1975-88, and still rising), and have shown to adapt well to captivity. Some calves have been captive-bred, and the annual survival rate of Orcas in Canada and the USA is 91%. Highlighted in the film Free Willy, captive Orcas (such as Lolita, Corky and Keiko) are currently at the centre of a major campaign movement around the world, which aims to rehabilitate the animals and release them back into the wild. Other problems that face the Orca stocks concern mainly food supplies – since Orcas do prey on fish such as herring and salmon, there is often competition between the cetaceans and fishermen for the fish – which most often results in the fishermen (or, in the case of Icelandic Orcas in 1956, the US Navy) ‘clearing the area’. Less evident is the fact that, since Orcas are at the top end of the food chain, much of their food is likely to carry high contamination from water pollution.

Geographic Distribution

Killer Whale Habitat

Killer Whale Habitat