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  The Mammals of Texas - Online Edition

Killer Whale
Order Cetacea : Family Delphinidae : Orcinus orca (Linnaeus)

Killer Whale (Orcinus orca).  Illustration by Pieter A. Folkens.Description. Killer whales are the largest of the dolphin family. Adult males reach up to 9.4 m in length although 8.2 m is average. Females typically reach 7 m in length with the maximum about 8.5 m. Maximum weight is about 7 metric tons. Body form is stocky, the snout is blunt, and the flippers are large and paddle-shaped. In males the dorsal fin may be up to 1.8 m tall, but is considerably shorter in females. Coloration is black dorsally and white ventrally from the chin to slightly behind the anus. An area of white extends up the side posterior to the dorsal fin and an oval white patch is located just above and behind the eye. Each side of both jaws has 10-12 slightly curved teeth that are about 13 cm in length and interlock when the mouth is closed. The teeth are oval in cross section.

Distribution in Texas. Killer whales are distributed worldwide, including polar seas. They are rare in the Gulf of Mexico. Known in Texas on the basis of one stranding on South Padre Island and one sighting in waters off of Port Aransas.

Habits. Killer whales are most often observed as gentle giants of marine aquariums but they are, in fact, the supreme carnivore of the world’s oceans. At sea they are usually seen in "pods" of 5-20, although up to 150 have been seen together at one time. Large groups probably consist of several pods which have temporarily aggregated. Pods themselves appear very stable for many years, with little emigration or immigration. They are highly cooperative and the group functions as a unit when hunting, making these delphinids extremely efficient predators. Groups usually contain adults of both sexes but sometimes females with young will form their own groups.

Food items include squid, fish, skates, rays, sharks, sea turtles, sea birds, seals, sea lions, walrus, dolphins, porpoises, and large whales such as fin whales, humpback whales, right whales, minke whales, and gray whales. They are even known to attack the sperm whale and blue whale. On the Atlantic coast of South America, as well as on islands of the Indian Ocean, killer whales have been observed lunging through the surf — and coming right onto the beach — in pursuit of elephant seals and sea lions. After such an attack the whales have to wriggle and slide back into depths adequate for swimming. In captivity, killer whales eat about 45 kg of food per day but free ranging animals probably require much more. Although these are obviously proficient and voracious hunters, killer whales are not known to have ever attacked a human.

The reproductive habits of these whales are poorly known. The males may mate with more than one female and mating may occur throughout the year, although most calves seem to appear in autumn or winter in shallow waters. Their period of gestation is about 12 months. Calves are approximately 2.4 m long at birth and reach sexual maturity when 4.9-6.1 m in length.

Illustration credit: Pieter A. Folkens.