Killer Whales Research Paper

Killer Whale, largest member of the dolphin family. Killer whales occur in more parts of the world than probably any other cetacean (see Whale). They occur in all oceans, both in the open ocean and close to shore, but are more common in the colder, more productive waters of both hemispheres than in the Tropics. Resident populations may cover an area of several hundred square kilometers. Transient populations often move through an area rapidly, swimming more than 1000 km (more than 600 mi) along a shoreline in a matter of days. Killer whales are black or deep brown overall, with striking white patches above the eye and from the lower jaw to the belly, and a fainter grayish-white saddle patch just under and behind the dorsal fin. Males are somewhat
larger than females, with mature females reaching lengths of up to 8.5 m (up to 28 ft), and mature males reaching lengths of up to 9.8 m (up to 32 ft). All killer whales have a prominent triangular dorsal fin in the middle of the back, but that of the adult male may grow to 1.8 m (5.9 ft) tall.
The flippers of both sexes are large and oval, unlike those of any other toothed whale. Killer whales may be solitary or live in groups of 2 to more than 50 animals. They feed on fish, squid, marine birds, pinnipeds (see Seal), and even other cetaceans. They generally cooperate during hunting, especially when feeding on large, warm-blooded animals such as penguins, seals, and porpoises. Killer whales have even been known to prey on blue whales, the largest species on earth. In most areas, killer whales have specialized feeding habits. In the Pacific Northwest of the United States and the Pacific Provinces of Canada, for example, resident populations feed mainly on salmon and other near-shore fishes, while transient populations feed primarily on harbor seals and porpoises. In several places in the southern hemisphere they habitually beach themselves as they rush ashore to take seals or sea lions in the turbulent surf zone, moving back to deeper water afterward. Killer whales use echolocation to gather information about their surroundings—that is, they send out high-frequency clicks that bounce off prey and other objects and they interpret the returning
echoes. Killer whales communicate by means of rapid-fire click trains that sound like rasps and screams, although when they are on the prowl for marine mammals, which have acute underwater hearing, they can be silent for hours at a time. Groups of killer whales seem to be remarkably stable, with males and females staying in their natal pods, or groups, for life.
Consequently, researchers believe that, to keep inbreeding to a minimum, mating does not occur between members of the same pod as often as it does between members of different pods. The female gives birth to a single calf 16 or 17 months after mating. The calf is nursed for 14 to 18 months. Killer whales are an important subject of mythology for many indigenous peoples, especially the Native Americans of the Pacific Northwest. The whales have not been hunted extensively by humans, although they have been hunted by some shore whaling operations, and some individuals have been taken as aquarium show animals from the waters around the Pacific Northwest and Iceland. Killer whales are perceived by many near-shore fishermen to be in competition with human fishing activity. Scientific classification: The killer whale belongs to the family Delphinidae of the suborder Odontoceti, order Cetacea. It is classified as Orcinus orca. The feeding activities of whales are directly related to their mouth and jaw structure and whether they possess baleen or teeth. Baleen whales are filter feeders with expandable mouths and
throats. Right whales have long, thin streamers of baleen for catching small prey. They swim slowly forward with open mouths continuously straining primarily krill, but also copepods and other small organisms from the water. Rorquals use a different style, called lunge feeding, to prey on krill and fish. These baleen whales move quickly into a dense school of prey and take a great gulp of up to 70 metric tons of water. With the mouth partly closed, the baleen curtains interlace from above and below, forming a filter at the front and sides of the mouth. The whale’s throat muscles then contract, and water is forced out through the baleen as the food is trapped inside the mouth and then swallowed. Whales are found in all the world's oceans and even in a few rivers. One species of dolphin, the pink river dolphin, lives only in the Amazon River and its larger tributaries. Some better-known whales, including the blue, finback, humpback, and gray whale, range widely and migrate between the tropics in winter and subpolar waters in summer. Humpbacks have separate populations in the northern and southern hemispheres and do not seem to cross the equator. Sperm whales and killer whales, or orcas, are wanderers without specific migratory routes. An individual sperm whale might, in its lifetime, swim around the world. Bibliography The Beautiful Whales. Word Count: 837