The killer whale: 6 facts about a powerful apex predator
- Killer whales are technically dolphins.
- These apex predators can even eat sperm whales.
- They have hierarchical societies with their own vocal dialects.
Orcas, known as killer whales, despite the fact that they are not whales, are highly intelligent animals that live in all the oceans of Earth. They are actually one of the most widely distributed mammals in the world, apart from humans.
They do tend to prefer colder waters, though. According to the US National Oceanic and Atmospheric Administration (NOAA), orcas are more abundant in colder waters, like those around Alaska, Norway, and Antarctica.
As of August 2022, there are at least 57 specimens held in captivity at sea parks and aquariums around the world. However, this practice is widely disapproved by animal welfare organizations, along with a large part of the general public, and is forbidden by some national laws, such as Canada’s Ending the Captivity of Whales and Dolphins Act.
The main argument against their captivity is that orcas are very social animals who, in the wild, live in tight-knit family groups and do not manage well when kept on their own. They also need a lot of daily exercises. They can swim up to 40 miles (64 kilometers) a day in search of food. So they don’t really thrive in concrete tanks, and they generally have shorter lives in captivity. Many people also object to their use for entertainment, as in trained dolphin shows.
1. Killer whales have a life expectancy of 50-80 years in the wild
In their natural habitat, orcas can live between 50-80 years, although this varies with sex. In captivity, however, their average lifespan is reduced to between 10-45 years.
In the wild, male orcas have an average lifespan of around 30 years, with a maximum life expectancy of 50-60 years. Female wild orcas tend to live longer than males. The average life expectancy of a wild female orca is around 50 years, with some living between 80 and 100.
"Granny", the oldest known, was estimated by the Center for Whale Research to be around 105 years old when she died in 2017.
2. Killer whales tend to start reproducing when they are 20 years old
Male orcas reach sexual maturity at around the age of 20 to 25, and they don’t typically mate until at least the age of 20. Between ages 12 and 15, their dorsal fin begins to grow taller and straighter, which indicates the beginning of sexual maturity.
Female orcas usually reach sexual maturity in their mid-teens. The average birthing rate is around one viable calf every 9 or 10 years. Female orcas are reproductive until around the age of 40 years old.
Mating and calving take place year-round, with gestation lasting from 15 to 18 months. As mammals, orcas feed their calf (they only have one per pregnancy) with milk. Calves will usually nurse until the age of two but will eat some solid food from around age one.
3. Killer whales are actually dolphins
One of the most interesting facts about orcas is that they are not whales at all, but dolphins. Killer whales, scientifically known as Orcinus orcas, are in fact the largest delphinid species, with an average length of 20 to 27 feet (6 to 8 meters) for males and 16 to 26 feet (5 to 7 meters) for females.
Male orcas weigh around 12,000 pounds (5,400 kg) or more, while females tend to weigh between 8,000–11,000 pounds (3,500-5,000 kg).
Killer whales belong to the family of toothed whales (Odontoceti), a suborder of cetaceans.
Not all whales have teeth; the blue whale, for example, uses baleen to feed itself. But oceanic dolphins, such as narwhals, beluga whales, and killer whales, do have teeth. Orcas have, in fact, 40 to 56 cone-shaped, interlocking teeth that can grow up to three or four inches (almost eight or nine centimeters) long.
Like bottlenose dolphins and porpoises, orcas also have rounded heads that end in a bulbous beak.
In short, they are physically more similar to dolphins than to whales.
4. Killer whales or whale killers?
Killer whales do actually kill some whales as part of their diverse diet, which includes fish, seals, squid, sea birds, sharks, octopods, and others sea animals. Although generalists, Orca pods can be picky - preferring one type of food over others.
Killer whales can even feed on blue whales, the largest animal on Earth, although they usually go after calves and not adults.
In fact, it is thought that Orcas were originally nicknamed “whale killers” by ancient sailors who saw them preying on larger whales. At some point, the nickname turned into “killer whales”. Their Latin name, Orcinus orca, translates to ‘whale of the kingdom of the dead.'
While it is true that orcas are at the top of the food chain, they have never killed a human in the wild, and attacks only tend to occur if they misidentify the human as prey. In most cases, the Orca appears to cease its attack once it realizes the mistake. In captivity, there have been a few deaths attributed to killer whales, almost all involving trainers or marine park staff, but it is not clear if these are due to accidents involving large whales in a small space, or whether confinement made them more aggressive.
5. Killer whales have the second largest brain in the animal kingdom
A killer whale can weigh between 8,000 and 16,000 pounds (3,600 to 7,260 kg). And its brain accounts for about 15 pounds (7 kg) of that weight. Scientists estimate that killer whales have an encephalization quotient or EQ (a relative measure of brain size compared with what would be expected based on body size alone) of around 2.5 —similar to that of a chimp, but much lower than some other dolphin species — bottlenose dolphins have an EQ of 5.3 (human EQ is 7.4).
Although larger brains are not necessarily smarter, research has shown that killer whales have spindle cells in their brains. These brain cells —which can also be found in humans and great apes— are believed to play a role in the processing of complex emotions, such as love and empathy, and perhaps grief. In humans, the cells occur in parts of the brain that are thought to be responsible for our social organization, intuition, and rapid “gut” reactions.
In 2018, a southern resident orca named Tahlequah, a member of one of the smallest orca communities located near British Columbia carried her dead calf’s body for 17 days. The calf had died shortly after birth, and her mother seemed to refuse to leave her in the sea—a behavior that scientists linked to grieving.
When other members of the pod helped the mother push away the dead calf, scientists believed they were observing a mourning ritual.
Other behavioral studies of killer whales reveal that they are not only emotionally intelligent but also socially intelligent. They live in groups called “pods”, which are led by a matriarch who holds and passes on collective knowledge, such as foraging strategies, to the new generations. Scientists interpret this as a form of “cultural transmission.”
Another sign of high brain development in the killer whale is given by a 2001 study based on a mirror test. In it, the authors studied the behavior of the killer whale in front of a mirror and concluded that it seemed to “possess the cognitive abilities required for self-recognition.”
6. Killer whales have their own language
Nobody calls into question that animals communicate in their own way. But each pod of killer whales tends to develop its own linguistic code. They use different sounds —such as whistles, pulsed calls, and clicks— to form a unique vocal dialect that is stable over time and that only the members of that pod know.
Mothers pass on this distinct vocal dialect to their offspring through social learning and imitation during the process of cultural transmission.
Scientists have counted up to 17 discrete calls per killer whale pod, with several possible modulations.