WHALES

killer whale

by Sarah Blue, Shawn Buell, Stephanie Creed, and Scott McCarthy

Appearance

Killer whales have a sleek, streamlined fusiform body; their physical characteristics are adapted for life in an aquatic environment. When male killer whales approach adulthood, they acquire typical male characteristics; they gain weight, and their spectoral flippers, dorsal fins, and flukes grow longer than those of the females. Each lobe of the tail is called a fluke; flukes are flattened pads of tough dense, fibrous, connective tissue, complete without bone. Longitudinal muscles of the back, both above and below the spine, and caudal peduncle move the flukes up and down.

Male killer whales average between 22 and 27 feet long and usually weigh between 3,000 and 12,000 pounds. Female killer whales average between 17 to 24 feet long and weigh between 3,000 and 8,000 pounds. The largest male killer whale ever recorded weighed 21,000 pounds and was 32 feet long.The largest female killer whale recorded was 28 feet long and weighed 15,000 pounds.

A whale is a very large and powerful animal. Different types of whales have different defence systems. Some whales have a very powerful tail slap. A tail slap would be powerful enough to kill a human. Some whales have very sharp teeth and powerful jaws such as the killer whale.

Habitat

During the summer months, most whales inhabit the icy waters of the Arctic and Subarctic, where water temperatures may be as low as 0 degrees C (32 degrees F). They swim among icebergs and ice floes. Whales are generally found in shallow coastal waters, often in waters barely deep enough to cover their bodies, foraging along the productive continental shelf areas. They may also be found in deeper waters. In the summer, many populations are found in warmer waters. Many species of whales seem to be well-adapted to both cold ocean habitats and warmer fresh water habitats. Some types of whales are coastal, that is, they stay near shore, and others are oceanic, that is, they roam the open seas. Several species give birth and rear young in protected coastal bays and lagoons.

Behavior

Whales live in groups called pods. The size of the pods usually varies from less than 5 to about 30 individuals. A pod is a cohesive long-term social unit, usually consisting of males, females and calves of varying ages. Several smaller pods may join occasionally to form larger groups of 50 or more whales called herds.There is an occasional trade of members between pods, especially during breeding season.

Whales in a pod appear to make strong social bonds; certain animals prefer associating with one another. As with most species, there is a social hierarchy within a group of whales; this social hierarchy is dominated by the females.

Food Supply

Killer whales are the dominant predators in the ocean, and are opportunistic feeders; their diet varies from one region to another. They eat about 67% fish, 27% marine mammals, and 6% skid. Killer whales in the Bering Sea (near Alaska) eat 65% fish, 20% squid, and 15% marine mammals. Food for the killer whale consists of different kinds of fish like salmon, cod, flat fish, hake, herring and smelts; they also eat sea birds. They also prey on seals, sealions, walruses and occasionally prey on sea otters and penguins. Whales eat 3% to 4% of their body weight in food per day. A baby whale eats up to 10% of its body weight during growth periods.

Whales are like packs of wolves and lions; they often hunt in pods for food. They work together to encircle and herd the prey into small areas before attacking. Killer whales slide out on sand bars to pursue prey. They also surface from under the ice floes to knock prey into water. They don't chew their food; they swallow their food whole or tear it into large chunks. Beluga whales are opportunistic feeders; they prey on about 100 different kinds of primarily bottom-dwelling animals. They eat octopus, squid, crabs, shrimp, clams, snails, sandworms, and fish such as capelin, cod, herring, and smelts.

Life Cycle and Young

Male whales become sexually mature at about eight to nine years of age, and females at about four to seven years. Breeding generally takes place in small bays in March through May, about 10 months after calving. A single dominant male may mate with several females.

A baby whale swims close to its mother and can be carried in the mother's slip stream, a type of wake which develops as the mother swims. This helps the mother and calf to keep up with the pod. A calf may nurse for 12 months. To nurse, a calf swims on its side and suckles from nipples concealed in abdominal mammary slits.

A killer whale calf's upper teeth erupt at two to four months.The lower teeth erupt at three or four months. Calves begin to take in a few fish at three to four months.They eat solid food consistently at four to five months. Calves grow about 2.6 feet (80 cm) during their first year, and about 2.2 feet (67cm) during their second year. Calves can vocalize within days of birth, but sound production is shaped with age. Vocal behavior is not predetermined; calves learn during the course of development which calls to make and under what circumstances.

Enemies and Endangerment

A whale does not have very many enemies. One of a whale's most dangerous enemies is the human species. Humans have been killing whales sincee the 12th century; whalers around the world have killed thousands of whales. Other threats to whales are toxins, oil spills, diseases, and garbage in the oceans. Oil spills are very dangerous because not only do they kill whales, but they will kill any thing in the oceans. Garbage kills marine life around the world every year. Disease also kill whales and marine life; sickness could cause a whale to become disoriented and to beach itself, causing it to die. There are many different toxins in the world such as radiation, but humans have been making an attempt to clean it up.


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