Species: Orcinus orca
Basic orca facts:
The orca, or killer whale, is the biggest member of the dolphin family.
Orcas are apex predators, with no animals that hunt them (except for humans). They even prey on large whales and sharks. Orcas are sometimes called the wolves of the sea, because they hunt in groups like wolf packs.
Male killer whales measure 20-26 feet (6-8 meters) long, and weigh as much as 22,000 pounds (10,000 kilograms). Females are slightly smaller, at 16-23 feet (5-7 m) in length and an average weight of 16,500 pounds (7,500 kg).
The orca whale's large size and strength make it among the fastest marine mammals, able to reach speeds in excess of 30 knots (about 34 mph, or 56 kph).
Scientists predict that the one species of orca will likely be split into three or five different sub-species eventually.
What do killer whales eat?
Orcas eat different foods in different locations. In the Pacific Northwest, their diet is 90 percent salmon, but other populations eat turtles, seals, herring and tuna.
With their 5-inch-long (13 centimeters) teeth, orcas can kill and eat sharks by holding them upside down underwater for 15 minutes. They can also eat birds; a captive whale discovered that it could regurgitate fish onto the surface, attracting sea gulls, and then eat the birds. Four other killer whales then learned to copy the behavior.
Orcas are highly social and intelligent creatures. Some populations are composed of matrilineal family groups, known as pods, which are the most stable of any animal species. There appear to be both resident and transient pod populations of killer whales. Resident populations eat more fish, while transient populations feed on seals and other marine mammals.
Female killer whales mature at around age 15. Mothers calve, with usually a single offspring, about once every 5 years after a 17-month pregnancy. In resident pods, birth occurs at any time of year, although winter is the most popular. Mortality is extremely high during the first six to seven months of life, when nearly half of all calves die. According to observations in several regions, all male and female killer whale pod members participate in the care of the young.
Females breed until age 40, meaning that on average they raise five offspring. The lifespan of wild females averages 50 years, with a maximum of 80–90 years.
Males sexually mature at the age of 15 but do not typically reproduce until age 21. Wild males live to around 29 years on average, with a maximum of 50–60 years.
Where orcas live:
Orca whales are found in all oceans and most seas, from the Arctic to the equator. Due to their enormous range, numbers and density, distributional estimates are difficult to compare, but they clearly prefer higher latitudes and coastal areas.
Very occasionally, killer whales swim into freshwater rivers, where they have been documented 100 miles (161 kilometers) inland.
Conservation Status: Not enough data
Because orcas may actually be different species, it's difficult to know how threatened they are.
Some experts say that the combined effect of declining prey resources and the effects of pollutants has caused a 30 percent global reduction over three generations.
In late 2005, the "southern resident" population of killer whales that inhabits British Columbia and Washington state waters were placed on the U.S. Endangered Species List.
Habitat disturbance caused by noise and conflicts with boats is also a significant worldwide threat.
Odd facts about orcas:
Orcas have the second-heaviest brains in the marine mammal world.
Orcas are the widest ranging mammals after humans.
Individual killer whales can often be identified from their dorsal fin and saddle patch. Variations such as nicks, scratches, and tears on the dorsal fin and the pattern of white or grey in the saddle patch are unique. Published directories contain identifying photographs and names for hundreds of North Pacific animals.
Killer whales feature strongly in the mythologies of indigenous cultures, with their reputation ranging from being the souls of humans to merciless killers.
Orcas and Pilot whales are the only non-human species in which the females go through menopause and live for decades after they have finished breeding.
All members of a resident orca pod use similar calls, known collectively as a dialect. Dialects are composed of specific numbers and types of repetitive calls. They are complex and stable over time. Call patterns and structure are distinctive within complex female-led social structures.
Because females can reach age 90, as many as four generations travel together. Individuals separate for only a few hours at a time, to mate or forage.