Killer Whales Essays - Megafauna, Baleen Whales, Apex Predators

Killer Whales The scientific order of all types of whales is Cetacea. This large order is broken down into three further groups as well: the toothed whales or Odontoceti, which includes killer whales, dolphins, porpoises, beluga whales, and sperm whales, the baleen whales or Mysticeti, which include blue whales, humpback whales, gray whales, and right whales, and the Archaeoceti order, which are all now extinct. The genus of these species is Orcinus orca. Family. The killer whale is the largest in its family of delphinid. Bottlenose dolphins, common dolphins, and Pacific white-sided dolphins are included in this group as well. The scientific name for this family is Delphinidae. Fossil Record. Modern forms of both odontocetes and mysticetes can be seen in the fossil record of five to seven million years ago. Scientists believe that early whales arose about fifty-five to sixty-five million years ago from, now extinct, ancient land mammals that happened to venture back into the sea. Habitat And Distribution: Distribution. Killer whales can be found in all oceans of the world. They are the most numerous in the Arctic Ocean and the Antarctic. However, their distribution is limited by seasonal pack ice. Habitat. The main living environment for killer whales is open oceans but they can also be found in coastal waters as well. Migration. Killer whales are very important in the oceans because they cause much of the migration of many fish and other prey. The movements of the killer whale to and from certain areas cause the other prey to move as well. Population. The worldwide population of killer whales is unknown, however they are not endangered whatsoever. Specific populations in a few areas have been estimated in recent years and some areas of the Antarctic alone have about 180,000 killer whales. The population can be distinguished because killer whales travel in pods, or groups. The resident pods can vary from as few as five to as many as fifty whales. The transient pod size varies from one and seven individuals. Physical Characteristics: Size. Male killer whales average about twenty-two to twenty-seven feet and usually weigh between 8,000 and 12,000 pounds. The largest male ever recorded was thirty-two feet and weighed about 21,000 pounds. As a male approaches adulthood, it acquires the typical male characteristics: it gains weight, and its pectoral flippers, dorsal fin, and flukes grow larger than those of females. Female killer whales average about seventeen to twenty-four feet and usually weigh between 3,000 and 8,000 pounds. The largest female recorded was twenty-eight feet and weight about 15,000 pounds. Body Shape. The killer whale has a sleek, streamlined body. Its physical characteristics are adapted for life in an aquatic environment. Coloration. Killer whales are easily recognized by their distinct coloration. The dorsal surface and pectoral flippers are black, except for the area below and behind the dorsal fin. The ventral surface, lower jaw, and undersides of the tail flukes are mostly white and the undersides of the tail fluke are lined with black. A white "eyespot" is located just above and slightly behind each eye and a gray saddle is located behind the dorsal fin. The distinctive coloration of killer whales is a type of disruptive coloration, a camouflage in which the color pattern of an animal contradicts the animal's body shape. By the flickering, filtered sunlight of the sea, other animals may not recognize a killer whale as a potential predator. Thus, making it easy for the killer whale to get to its prey. Body Parts. A killer whale has distinct pectoral flippers, or forelimbs. They have the major skeletal elements of the forelimb's of land mammals, but they are foreshortened and modified. They are rounded and paddle-like and are used mainly to steer and, with the help of the flukes, to stop. The flukes are the lobe of the tail on a killer whale. They are flattened pads of tough, dense, fibrous connective tissue, completely without bone. A large male killer whale may have tail flukes measuring up to nine feet from tip to tip. All traces of hind limbs have disappeared except for two reduced, rod- shaped pelvic bones, which are buried deep in the body muscle. These reduced hind limbs are not connected to the vertebral column however. The dorsal fin, like the flukes, is made of dense, fibrous connective tissue with no bones. It acts as a keel, stabilizing a killer whale as it swims. The arteries in this fin help to maintain body temperature. In males, the dorsal fin is tall and triangular and in females it may by