Orcas (Orcinus orca) often referred to as, Killer whales, get their name from their reputation of being ferocious predators, exhibiting almost hateful behaviors when toying with their prey. Interestingly, however, killer whales are not true whales. They are very large dolphins, reaching lengths of 33 feet (10 m) and weights of at least 10 metric tones (22,000 pounds). Killer whales and other dolphins are thought to be some of the smartest animals on the planet, challenging the great apes (chimps and gorillas) for the top spot. They are also extremely curious and often approach people to investigate. Their intelligence is likely both a result of and a driver of their complex social structures. They are intelligent, playful, powerful animals – a worrisome combination if you happen to be their preferred prey. Different killer whale populations specialize on different prey types, including large bony fishes; seals, sea lions, and other large marine mammals; and penguins; among other things.
Though all killer whales, worldwide, are considered to be members of the same species, there are several known populations that have slightly different appearances, sizes, and behaviors. These include populations that are somewhat territorial and do not migrate long distances (the so called resident populations) and those that are more migratory in nature (the so called transient populations). Furthermore, some transient populations stay near the coast and overlap with resident populations, while others are oceanic. Some killer whale scientists believe that these populations may represent different species, and recent research suggests that there may be as many as 16 different species of Killer Whale. To date, the new species have yet to be described, and the cosmopolitan species Orcinus orca is considered to cover all individuals around the world, regardless of behavior or appearance.
Though they are powerful hunters and are known to exhibit somewhat tortuous behavior towards large sharks and other marine mammals, killer whales have never been known to attack humans in the wild. This is a somewhat puzzling lack of aggressive behavior, as people would be extremely easy prey for this species. In captivity, however, male killer whales have killed several trainers in the last few decades. These large, marine predators are not meant to be kept in small tanks in captivity, and they seem to eventually snap and exhibit aggressive behaviors toward their handlers. In addition to their capture for display in public aquariums, low numbers of killer whales have been regularly hunted for food in some regions around the world.