The killer whale, or orca, is a toothed whale belonging to the oceanic dolphin family of which it is the largest member.
Although it is actually a dolphin, it got the name killer whale because of its fierce reputation. Ancient sailors who witnessed their viscous attacks on larger whales referred to them as "whale killers.” Over time, this name was eventually changed to killer whales.
Although whales and dolphins do not resemble most other mammals, they are known to be closely related to the even-toed hoofed mammals (e.g. pigs, cattle, camels, hippopotami, etc.). This relationship is based on DNA studies and extensive fossil evidence.
The orca is one of the world's most powerful predators. They are immediately recognizable by their distinctive black-and-white coloring and rather large dorsal fin. This fin is tall and erect in the male, but shorter and curved in the female.
Male killer whales are generally larger than the females. An adult male will weigh between 8,000 to 12,000 pounds and have a length of 20 to 26 feet. They can be found worldwide in all oceans from Arctic pack ice to the tropics. They exploit a variety of habitats from shallow coastal areas to deep waters off the continental shelf.
Although they can be found in open ocean, they seem to be most abundant in coastal waters. Killer whales live on a variety of prey including fish, seals, baleen whales, seabirds, and sea turtles. They live in pods of three to 30 individuals. Some pods are migratory and eat mainly marine mammals, while others are resident and eat mainly fish. Larger prey is often hunted in a coordinated, cooperative manner.
A gray whale that is twice the size of a killer whale and correspondingly as strong, becomes terrified when a pack of killer whales appears. When polar bears are in the water, they are subject to attack by killer whales. Recent studies have shown that even a group of fearsome and dangerous white sharks will leave a prime hunting area and not return for up to a year when a pod of killer whales pass through the area.
Killer whales are relatively slow reproducers and their numbers suffer from pollution, commercial fishing gear, and whaling by several countries. In addition, others are captured for use in aquariums and zoos where they are easily trained. However, these animals only have a life expectancy of about a quarter of what they enjoy in the wild.
Larrie Stone is a retired Dana College science professor.