Killer whale
The killer whale, Orcinus orca, is perhaps the most recognized species of cetacean in the world. They can be found throughout the world’s oceans, they are viewed at Oceanariums around the world, and they have been depicted in movies such as Orca and Free Willy. Although most people only have the chance to view them at oceanariums, watching wild killer whales in their own habitat is a truly breath-taking experience. One of the best places to view these animals is in the Pacific Northwest (Washington State and British Columbia), where two different races of killer whales can be found. The whales found here, which have been intensively studied since 1970, are separated into two distinct groups, or races, based on home range, group size, foraging strategy, and behavior. These differences are summarized in the “Quick Facts” section.
One of the most remarkable differences between Resident and Transient killer whales is their foraging strategy. Residents eat fish almost exclusively, whereas Transients specialize in hunting other marine mammal species. Transients primarily feed on seals, sea lions and small cetaceans, but they have been known to kill and eat large baleen whales, even the largest of all, the blue whale! Residents and Transients do not interbreed or associate closely with eachother. In fact, there are physical differences in the shape and placement of the dorsal fin between the two races, indicating that they have been reproductively isolated for many generations.
Killer whales live and travel in family groups called pods. Vocalizations analyzed from different pods showed that each pod has its own dialect, a set of sounds that every member of the pod learns. This distinct set of sounds is produced often by the whales and is probably used to maintain contact between pod members while foraging or travelling. In addition, separate dialects help to prevent inbreeding, or mating within a pod since pods will join together for mating.
Several pods in a given region may have similarities in their dialects, i.e., some of the sounds that make up their dialect may be the same. These pods are thought to be more closely related and are said to be in the same clan. Therefore, a clan is a language group consisting of a group of pods sharing some of the calls of their dialects. Thus, recording and analyzing sounds made by killer whales is an excellent way for researchers to determine family relationships among communities of killer whales. It also serves to illustrate the highly organized social structure of killer whales.
