Orcas (Orcinus orca) are often called killer whales, even though they almost never attack humans. In fact, the killer whale name was originally "whale killer," as ancient sailors saw them hunting in groups to take down large whales, according to Whale and Dolphin Conservation (WDC).
Today, orcas are recognized as among the most widely distributed mammals on the planet, occupying every ocean. They are incredibly social, diverse and ferocious marine predators with a diet ranging from penguins to great white sharks.
How big is an orca?
Orcas are the largest members of the dolphin family. Males are bigger than females, but they vary in size and weight, depending on the type of orca. The largest orca ever recorded was a staggering 32 feet (9.8 meters) long and weighed 22,000 lbs. (10,000 kilograms), according to SeaWorld. That's longer and heavier than most motorhomes.
Orcas are known for their long dorsal fin (the fin on the animal's back) and black-and-white coloring. The black-and-white coloring helps to camouflage them by obscuring their outline in the water. Just behind the dorsal fin is a patch of gray called a "saddle" — because it looks like a riding saddle.
An orca's body is cylindrical and tapers at each end to form a hydrodynamic shape. This shape, along with the orca's large size and strength, makes it among the fastest marine mammals, able to reach speeds in excess of 30 knots (about 34 mph, or 56 km/h). Orcas have massive teeth, which can grow up to 4 inches (10 centimeters) long, according to National Geographic.
What do orcas eat?
Orcas are apex predators, at the top of the food chain. No animals hunt orcas (except for humans). Killer whales feed on many different types of prey, including fish, seals, sea birds and squid. They can also take down whales larger than themselves, such as minke whales, and they are the only animal known to predate on great white sharks, according to The Natural History Museum in London. Killer whales have even been reported to kill swimming deer and moose, according to a chapter on orcas in "Primates and Cetaceans" (Springer, 2014).
Orcas use many different techniques to catch prey. Sometimes they beach themselves to catch seals on land, jumping from the water onto land. Orcas will also work together to catch larger prey or groups of prey, such as schools of fish, according to the International Union for Conservation of Nature's (IUCN) Red List. They can use echolocation to identify their prey by creating sounds, or sound waves, that travel through the water. These waves echo off objects, including prey, which the orcas can use to locate them, according to SeaWorld.
Orca attacks on humans
There is no record of an orca ever killing a human in the wild. This is because humans are not part of their natural diet. Occasionally, an orca may mistake a human for something they do eat, such as a seal. In 2017, an orca was caught on camera charging at a surfer during the Lofoten Masters surfing competition in Norway. The orca seemed to pull out of the attack just before making contact. The Norwegian Orca Survey said in a Facebook post that the orca likely realized the surfer was not a seal at the very last second.
In 2005, a 12-year-old boy was "bumped" by a killer whale near Ketchikan, Alaska, in what may have been an aborted attack — similar to the surfer in Norway — or simply curiosity on behalf of the orca, according to the Associated Press, via The Seattle Times. The Associated Press reported that a surfer was bitten in California in the early 1970s, which is the only relatively well-documented case of a wild orca actually biting a human. Orcas in captivity, however, have attacked and killed people.
Although wild killer whales do not intentionally harm people, they have attacked boats. There were many reports beginning in the summer of 2020 of orcas ramming into and causing damage to sailing boats off the coast of Spain and Portugal, according to BBC News. Three juvenile male orcas were involved in most of the attacks, and marine biologists investigating the incidents believe that the young males were playing with the boats by targeting the rudders and pushing the boats around.
Life in the pod
Orcas are very social creatures and live in family groups called pods, which have up to 50 members, according to the University of Michigan's Animal Diversity Web (ADW). These pods are made up of related mothers and their descendants, known as matrilines. A male orca will stay with its mother for life, while daughters may spend time away after having calves of their own, according to the wildlife charity Whale and Dolphin Conservation (WDC). Pods often have their own distinctive calls, or dialects, to communicate, but they will associate with other pods and can come together to form even larger, temporary groups.
Size: Up to 32 feet (9.8 m) long
Life span: Up to 100 years
Conservation status: Data deficient
A female killer whale will give birth to one offspring at a time every three to 10 years. The gestation period usually lasts for around 17 months according to SeaWorld. Orcas work together to take care of the young, and other females in the pod will often help with the rearing.
Female killer whales have an average life span of 50 years, but some individuals are estimated to have lived up to 100 years. Males live shorter lives, with an average life span of 29 years and a maximum life span of 60 years, according to the Center for Whale Research in Washington state.
Where do orcas live?
Killer whales are the most widely distributed mammals, other than humans and possibly brown rats, according to SeaWorld. They live in every ocean around the world and have adapted to different climates, from the warm waters near the equator to the icy waters of the North and South Pole regions.
Orcas have been known to travel long distances. For example, one study found that a group of orcas traveled from the waters off of Alaska to those near central California, according to IUCN — a distance of more than 1,200 miles (1,900 km).
Are there different types of orca?
All orcas are currently listed under one species, Orcinus orca. However, there are recognizable differences between populations, and biologists have identified several distinct forms, known as ecotypes, which may actually be different species or subspecies, according to the National Oceanic and Atmospheric Administration (NOAA).
Killer whale ecotypes can vary in size, diet and behavior. There are currently 10 described ecotypes: five in the Northern Hemisphere and five in the Southern Hemisphere, according to WDC. In the North Pacific, scientists have identified resident orcas, which tend to have small ranges — hence the name — and specialize in catching fish. Bigg's killer whales, or transient orcas, can also be found in the North Pacific. These orcas travel great distances and hunt mammals such as seals and whale calves. Offshore orcas can also be found in this region. They live far from coastlines and have been seen eating fish and sharks, but relatively little is known about them.
The Northern Hemisphere is also home to North Atlantic Type 1 and Type 2 killer whales. Type 1 orcas are generalist eaters and have been observed eating fish and seals around European countries, including Norway and Scotland. Type 2 orcas are rarer and mainly eat other whales and dolphins.
In the Southern Hemisphere, there are Type A, Type B (large), Type B (small), Type C and Type D killer whales.
—Type A orcas travel in and out of Antarctic waters, following the migration of their main prey, minke whales.
—Type B (large) animals are also called pack ice orcas, because they hunt seals in Antarctic pack ice.
—Type B (small) killer whales, also called Gerlache orcas, have been seen eating penguins, but their complete diet is unknown.
—The same is true for Type C and Type D orcas, though both of these have been observed eating fish.
—Type C, or Ross Sea orcas, are the smallest ecotype and are usually found in eastern Antarctica.
—Type D, or subantarctic orcas, are very rare, and there is still much to learn about them.
Are orcas endangered?
The orca is currently listed as "Data Deficient" by the IUCN, which means its conservation status is unknown. Scientists didn't have sufficient data when it was last assessed in 2017 due to the uncertainty regarding its taxonomic classification — whether orcas should be split into different subspecies or species. The IUCN noted that as a single species, the killer whale is abundant and widely distributed. However, they still face threats from human activities and some regional populations, such as the orcas dependent on bluefin tuna in the Strait of Gibraltar, have declined significantly.
Human civilizations around the world kill orcas directly and indirectly. They are still hunted for food in small numbers, or as a means to control their population, in Greenland, Japan, Indonesia and the Caribbean, according to the IUCN. Contaminants in the ocean and seas, such as chemicals and oil, pose a threat to orcas along with disturbance by boats, overfishing and other disruptions to their food supply and climate change, according to IUCN.
Killer whales are protected in the U.S under the Marine Mammal Protection Act (MMPA). Southern resident killer whales are also listed under the Endangered Species Act as they are at particular risk of extinction, due to threats like noise from boat traffic and a decline in the salmon population — their preferred food. A subpopulation of transient killer whales (AT1) is also listed as "depleted" under the MMPA. The population consists of just seven individuals, following a dramatic decline in the wake of the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, according to NOAA.
A SeaWorld orca named Tilikum was the focus of the popular 2013 documentary "Blackfish," which took a critical look at killer whales in captivity. Tilikum was involved in three human deaths, including that of SeaWorld trainer Dawn Brancheau in 2010. The documentary created a public backlash against SeaWorld, and in 2016 the marine park chain announced that it was ending its killer whale breeding program, Live Science previously reported. Tilikum died of a bacterial infection at SeaWorld in 2017 at the age of 36.
Another famous captive orca was Keiko, who played Willy in the 1993 film "Free Willy." Keiko lived in a marine park in Mexico, but after the film's release, an international campaign was launched to return him to the wild Icelandic waters from which he was captured when he was about 2 years old. Keiko was trained to catch wild fish and was released off the coast of Iceland in 2002. He swam to the coast of Norway but died of pneumonia, 18 months after his release, at the age of 27, according to BBC News.
An all-white orca named "Iceberg" was spotted in waters around the Commander Islands, off the east coast of Russia, in 2010, Live Science previously reported. The ghostly white dorsal fin of this mature male stood out dramatically from those of its black-and-white podmates. Researchers at the Far East Russia Orca Project (FEROP), who discovered Iceberg, found more white orcas in Russian waters, and suggested that most are albino, although it is not known for certain, according to WDC. Albino orcas could indicate inbreeding in the population.
- Whale and Dolphin Conservation (WDC)
- SeaWorld: Killer whale
- National Geographic: Orca
- IUCN Red List of Threatened Species
- University of Michigan's Animal Diversity Web (ADW)
- NOAA Office of Protected Resources: Killer whale
- Center for Whale Research
This article was updated on March 23, 2021 by Live Science staff writer, Patrick Pester.