Why is the orca a top predator?

Answer 1

The killer whale, (Orcinus orca), is the largest member of the group of marine mammals known as dolphins (family Delphinidae). They are called killer whales because they attack and consume whales or other large prey such as seals and sea lions.

General description: Adult killer whales generally grow to a length of approximately 27 feet (8.2 m). Females grow to an average length of about 23 feet (7 m). Adults may weigh as much as 10 tons. Killer whales are predominantly black in color with large white patches under the jaw and above and behind each eye. Much of the ventral surface of killer whales is also white and there are large white patches which extend from the ventral area onto the flanks. A gray or white saddle area is often found behind the dorsal fin. This area is highly variable and is one of the characteristics used to identify individual whales. The very tall dorsal fin is characteristic of this species. The dorsal fin of the male may reach 6 feet in height. Dorsal fins in females usually do not exceed 3 feet in height.

Distribution and migration: Killer whales occur in all of the earth's oceans and seas. They are found throughout the marine waters of Alaska but occur most commonly over the waters of the continental shelf from Southeast Alaska through the Aleutian Islands and northward into the Chukchi and Beaufort seas. Killer whales migrate northward throughout the Bering Strait in the spring as the pack ice retreats. They leave the Beaufort and Chukchi areas in the fall when the ice advances. Killer whales in the Pacific Northwest and Alaska occur in groups of animals called pods. Most pods in Alaska number fewer than 40 animals. The individuals which comprise each pod change very little. Killer whale pods are matrilineal and consist of a female and her offspring of both sexes. Some pods are seen throughout much of the year in certain areas and are termed "resident" pods. Other pods appear to move over broad areas and are termed "transient" pods. Killer whales are quite vocal, and each pod appears to have its own unique, recognizable type of calls which do not change over periods as long as 25 years.

Abundance: During the 1980s, photoidentification techniques were used for the first time in Southeast Alaska and in Prince William Sound to determine the number of individuals and pods of killer whales occurring in those two areas. Following the Exxon Valdez oil spill, these studies were expanded and carried out on a more systematic basis. As a result of this research, approximately 250 animals in 15 pods have been identified in Prince William Sound. Approximately 160 animals have been identified in Southeast Alaska; approximately 100 animals have been identified in the area from Kodiak to the Shumagin Islands; and another 100 animals have been identified in the Bering Sea. Because some areas of Alaska have never had any photoidentification research done, substantial numbers of killer whales may remain to be identified and counted.

Food habits: Killer whales are opportunistic feeders and have been observed to prey on virtually any large marine animal available. Resident pods appear to feed primarily on a wide variety of fish such as salmon, herring, halibut, and cod. Transient pods feed primarily on any available species of marine mammal. The stomach of a killer whale found stranded near Prince William Sound contained a harbor seal, a harbor porpoise, and a Steller sea lion. Killer whales also have been observed to prey on river otters, squid, and several species of birds. Killer whales may briefly leave the water to grab seals and sea lions from the shore. Animals within a pod often feed cooperatively. When preying on large animals such as gray or humpback whales, the killer whales may attack as a pack, tearing away at the prey animal from several angles. When preying on schooling fish, smaller killer whales may swim close to the beach to drive the fish from shallow waters out to the rest of the pod. Large groups of killer whales are often involved in hunting schools of fish. Smaller groups (2-8 animals) are more often used when preying on marine mammals such as seals or porpoises. Little is known about the diving behavior of killer whales. Typical dive times last 3 to 5 minutes although this is highly variable, depending on the type of activity in which the animal is engaged.

Reproduction: Killer whales are long-lived animals and reproduce slowly. The maximum age which these animals can attain has not been determined but may be at least 34 years, based on counts of growth lines in the teeth. The annual Birth Rate has been estimated at 4 to 5 percent but may be higher following the deaths of several animals in a pod. In stable pods, some females may not breed at all. Much remains to be learned about the reproductive behavior of killer whales. Females are believed to become sexually active at 10 to 16 years of age when they are approximately 14 to 17 feet long. Young are born at intervals of three to eight years, although animals born in captivity have borne young 19 months apart. The gestation period has been estimated at 15 to 16 months. In the north Pacific, most births appear to occur between fall and spring.

Sources of mortality: Humans are the only predators of killer whales. Killer whales have been taken throughout the world for meat and oil. Many killer whales have also been removed from the wild for public display. In recent years, killer whales have begun removing black cod (sablefish) from longlines set by Alaska fishers. This has resulted in several of the animals being shot. Such shooting is no longer legal.

Answer 2

There are many interesting facts about orcas. They can measure to 33 feet and weigh around 5,400 kilograms. Females can live to 90 years old and males for 50-60 years. They have no natural predators have been sighted in eating Great White Sharks and blue whales.

Answer 3

Because male killer whales (orcas) can be up to 33 feet! And can kill any creature in or near the ocean including the great white shark!

Answer 4

Orcas are actually dolphins!