| Name | Orca | Diet | Carnivorous |
| Scientific name | Orcinus orca | Weight | 3 to 10 metric tons (3.3 to 11 short tons) |
| Pronunciation | Awe-rkah | Length | 5 to 9.8 meters (16.4 to 32 feet) |
| Classification | Mammalia, Artiodactyla, & Cetacea | Location | Cosmopolitan distribution |
The Orcas
Orcas, also known as the wolves of the sea for their pack-hunting behavior, are the largest members of the dolphin family!
These marine mammals are renowned for their specific black-and-white coloration.
Apart from this, their highly complex social structures and ability to learn things are among the many adaptations that wildlife enthusiasts and scientists find awe-inspiring about them!
If you’re eager to learn about these apex predators, keep reading! We’ve gathered a long list of incredible facts about orcas!
Taxonomy and Classification
Orcas are sometimes called killer whales. Scientifically, they’re known as Orcinus orca and are part of the Delphinidae family alongside other oceanic dolphins.
Their family dates back to 11 million years ago. Shortly after their appearance, the orca lineage diverged, giving rise to Orcinus meyeri, the oldest known member of the Orcinus genus.
Approximately 5 million years ago, the killer whale appeared as well, the only Orcinus species that survived till the present time.
Genetic studies show that the closest extant relative of the orca is the snubfin dolphin.
Although scientists do not currently recognize orca subspecies, studies show that at least five types could be classified as orca races, types, or subspecies.
Physical Characteristics
Orcas are most renowned for their distinctive coloration, making it impossible to mistake them for another aquatic creature.
Their bodies are covered in a black-and-white pattern as follows:
- Black on the upper side that contrasts with two round eye spots.
- White on the underside, extending from the lower jaw to the genital area and becoming narrow between the flippers; then, the white patch gets a bit wider and extends into lateral flank patches.
- The fin is black on top and white on the underside.
- The genital area is colored differently in males and females, whereas newborns are yellow or orange in that region.
Although this pattern is quite well outlined, there may be some minor differences depending on the population.
For example, the pack ice population of the Antarctic is rather grayish than black, and its eye patches are larger than in the Type A population.
The form of the eye patches also differs slightly. The Ross Sea orcas, for example, have a teardrop-like eye patch that’s slanted forward, whereas pack ice orcas have oval-shaped eye patches.
Besides this, melanistic and albino orcas are known as well. (Check the Diet and Feeding section to learn about orca types.)
The pectoral fins of an orca are large and rounded. They are much larger in males than in females, as are the dorsal fins, which are twice as large in males.
Male orcas also have longer lower jaws, but they are powerful in both sexes and equipped with strong teeth.
Like other marine mammals, killer whales have something called a blubber that is 7.6–10 centimeters (3–4 inches) thick.
This is an insulating layer of vascularized adipose tissue beneath the skin.
Apart from their well-known coloration, orcas are famous for being the largest extant members of their family.
Males are bigger than females, measuring approximately 6–9.8 meters (19.7–32 feet) and weighing between 6 and 10 metric tons (6.6–11 short tons).
Females, on the other hand, measure only 5–7 meters (16.4–23 feet) and weigh 3–4 metric tons (3.3–4.4 short tons).
Habitat and Distribution
Orcas have a cosmopolitan distribution. However, scientists argue they prefer higher latitudes and coastal areas.
The most concentrated populations are in the northeast Atlantic off Norway, the north Pacific, the Southern Ocean, and the Gulf of Alaska.
Killer whales are sometimes spotted in freshwater rivers, as well, such as the Columbia River, Fraser River, and Horikawa River.
Specialists couldn’t establish any migratory routes, although they’ve seen some populations swimming along the coasts of Washington and British Columbia each summer.
As mentioned, orcas prefer coastal waters, so they’re not deep divers. However, they can go to depths of 100 meters (feet) if necessary.
Behavior and Social Structure
Orcas have quite a fulfilling lifestyle! Their daily routines include foraging, resting, traveling, and having fun with other orcas!
Like other dolphins, orcas often slapped their tails and jumped out of the water.
They even hold their heads above the water to see what happens in their surroundings! These activities are used just for fun, communication, or courtship displays.
These aquatic mammals are highly social. They have evolved to create complex social structures that can only be compared to those of higher primates and elephants.
Orca family groups are led by the eldest female, called the matriarch. The groups include all daughters and sons of the matriarch, her granddaughters and grandsons, and so on, sometimes up to four generations.
The group members are always together, except for when they are mating, which doesn’t take more than a few hours.
These family groups are called matrilines. One to four matrilines form a pod, and multiple pods form a clan. In turn, several clans form a community.
Pod members communicate through whistles, clicks, and pulsed calls.
Each pod has distinct vocalizations, called dialects, learned throughout their lives through contact with other pod members.
This takes us to another aspect highly discussed in the world of science – the intelligence of an orca.
It has been suggested that orcas can actually teach other orcas stuff and exhibit various teaching techniques and abilities to solve problems!
They’ve even learned how to trick fishermen and steal fish from longlines!
Some researchers stated that, after throwing a snowball out toward an orca, she repeated the activity by launching a ball of ice toward them!
Could it be that these creatures are smart enough to learn such things?
Diet and Feeding
Orcas are apex predators that feed in groups. That’s why they’re often nicknamed the wolves of the sea.
The type of prey they prefer highly depends on each population, as it seems they specialize in preying on different animals.
Only the groups living in tropical regions have a more generalized diet.
Check out below how these groups are divided and what they prefer feeding on.
- The North Pacific populations
- Residents (they reside in the northeast Pacific and feed on fish)
- Transients or Bigg’s (they reside in the northeast Pacific and feed on marine mammals)
- Offshore (they reside in the northeast Pacific and feed on schooling fish, possibly mammals, and sharks)
- The North Atlantic populations
- Type 1 (herring- and seal-eating orcas residing in Norway and Iceland; mackerel-eating orcas residing in the North Sea)
- Type 2 (orcas feeding on baleen whales)
- The Antarctic populations
- Antarctic or Type A (orcas feeding on minke whales)
- Pack ice or Type B1 (orcas living between Adelaide Island and the Antarctic peninsula and feeding on seals)
- Gerlache or Type B2 (orcas living in the Gerlache Strait and feeding on seals and penguins)
- Ross Sea or Type C (orcas feeding on Antarctic cod)
- Sub-Antarctic or Type D (orcas feeding on fish)
The fish-eating orcas are known to hunt over 30 fish species, among which are the following:
- Salmon
- Herring
- Chinook
- Sockeye
- Pink Salmon
- Chum salmon
- Eagle rays
- Common threshers
- Blue sharks
- Smooth hammerheads
- Shortfin makos
- Broadnose sevengill sharks
- Whale sharks
- Great white sharks
When preying on herring, orcas rely on a technique called carousel feeding, during which a group releases bursts of bubbles or flashes their undersides to catch the herring in a ball.
Once the fish are trapped, the orcas rely on their tail flukes to slap the ball, killing around 15 herring simultaneously.
Killer whales use a different technique when they aim at sharks. They initially lure the sharks to the surface and then use their tails to strike them.
When going after bottom-dwelling rays, orcas corner them, pin them to the ground, then bring them to the surface, where they delight in a tasty meal.
Here are other animals orcas prey upon:
- Smaller dolphins
- Porpoises
- Beluga whales
- Narwhals
- Sperm whales
- Gray whales
- Great whales
- Seals
- Swimming terrestrial animals, like deer
- Penguins
- Cormorants
- Gulls
If they choose to feed on a dolphin, orcas usually rely on a chasing technique, or they may try to separate an individual dolphin from a group.
Larger whales are attacked through a chasing technique, followed by a violent attack when the opportunity presents itself.
When going for marine mammals, orcas first try to disable them by throwing them in the air, ramming them, or landing on them. This prevents any injuries.
Stomach content showed that killer whales also engage in cannibalistic behavior, although scientists believe they just scavenged orca carcasses.
Reproduction and Life Cycle
Killer whales mate with members of other pods to avoid inbreeding (since each pod consists only of relatives). Sometimes orcas even go for members of different clans.
It is believed that they recognize how distantly related they are based on their vocalizations. However, not all orcas have the possibility of attaining such high genetic diversity.
Once fertilization occurs, females undergo a gestation period of 15–18 months, bearing only one baby, which is calved most often during the winter.
Each female gives birth only once in five years, and even then, 37–50% of calves die within the first seven months.
Mothers start the weaning process when their young are 12 months old. They are completely weaned when they’re two years old.
During this time, mothers teach their young feeding and hunting techniques, as well as how to socialize with other members of their pod.
Females become sexually mature at ten years old, although they’re most fertile at 20. Males mature later, at roughly 15 years of age.
However, they do not use their reproductive abilities until they turn 21.
Female orcas are among the few animals in the world that go through menopause, which typically occurs when they’re 40. After this, they can live well for 10–40 more years.
Males have a shorter life expectancy, as they only live up to 29 years on average. Some reach 60 years, although this happens rarely.
Ecological Role and Interactions
Since orcas are apex predators in their habitats, their ecological role is undeniable.
They maintain ecosystem balance, regulate population numbers, and thus keep their habitats healthy.
Besides this, many scientists regard the orca as an indicator species. This means that specialists rely on their well-being to understand how healthy and balanced the oceans are.
Orcas do not have any natural predators, and although highly social within their communities, they do not get along with other animals.
In fact, they’re known to harass and kill other marine mammals without any apparent reason.
Sea lions have also been observed attacking killer whales without reason. Either way, the interaction between killer whales and other marine mammals is highly complex.
Conservation Status and Threats
The orca is currently listed as Data Deficient on the IUCN Red List. This means that specialists assume orcas are abundant, but there isn’t enough information about them that would confirm the species is Least Concern.
Besides this, considering how many orca populations exist, it’s difficult to provide a global assessment.
Studies from 2006 suggest that at least 50,000 mature killer whales were alive back then.
Many populations have not been studied, so the authors argued that this estimation was an understatement.
Nonetheless, this doesn’t mean killer whales are safe and sound in their habitats.
They were deliberately hunted in the past. Even today, some fishermen shoot whales because of the depredation of longline fisheries.
Additionally, bio-accumulating contaminants highly affect orca populations by causing neurotoxicity, immunotoxicity, and reproductive issues.
Whale-watching tourism is another threat to orcas’ existence. The boats disturb their homes, whereas the noises produced by the vessels disrupt their foraging behavior.
Furthermore, the gases emitted by the vessels can negatively affect their health.
Another threat to some populations is the disappearance of their preferred prey as a consequence of habitat degradation and overfishing.
Killer whales may also be at risk of suffering from climate change, but this aspect hasn’t been thoroughly studied.
Unique Adaptations and Survival Strategies
Here are some unique adaptations orcas have developed:
- Orcas sleep with half of their brains awake because they cannot instinctively breathe; they have to be conscious to be able to breathe. To do so, they close only one eye at a time while sleeping.
- Orcas have excellent echolocation abilities, which means they rely on the echoes produced by their calls to identify prey.
- Their pulse drops to 30 beats per minute when they swim underwater.
- Orcas hear things through their lower jaws! The fat body in their hollow jawbones picks up sounds and transmits them to their ears.
- Orcas are highly intelligent, which is why they can specialize in hunting various animals.
- The fact that they often hunt in groups is part of why they’re such efficient hunters.
Cultural Significance and Human Interactions
Indigenous cultures consider orcas the ocean’s most powerful animals.
In their mythology, killer whales are described as highly complex creatures that take human form underwater and build towns under the sea.
Other cultures, such as the Ainu people, portray orcas as fortune-bearing animals.
In Western cultures, however, orcas were seen from a negative perspective due to their predatory lifestyle. They were historically described as enemies of other animals.
Nevertheless, people have changed their perspective over the years, thanks to scientific awareness.
Since then, it’s been the other way around – orcas have become the subject of people’s fascination!
They’re now kept in aquariums and seen by thousands of people. On the other hand, due to their highly social nature, many organizations working toward protecting animals argue against keeping orcas in captivity, as this leads to pathologies, stress, self-harm, and attacks on tankmates and humans.
In the wild, orcas haven’t been historically aggressive toward humans. However, since 2020, the number of killer whale attacks on sailing vessels has been rapidly increasing, reaching 500 by 2023.
Can it be that the constant intrusion into their territories makes them mad and they’re taking their revenge?
Future Prospects and Research
Orcas are undoubtedly fascinating creatures that have aroused the interest of thousands of scientists.
Their complex social structures and captivating hunting and learning abilities, indicating high intelligence, are by far the most discussed topics worldwide.
Other specialists focus their studies on outlining orca populations, distribution, and migratory routes.
This can help researchers assess how many individuals are left and determine whether their species is endangered.
We can help by keeping our vessels at least 50–100 meters (160–330 feet) away from orcas, avoiding circling them, and refraining from producing sudden noises that can startle them.
Additionally, we should avoid throwing stuff into the water that does not belong there, as this rubbish affects the ecosystem’s health.
Reporting any orca sightings with their description, precise location, and number of individuals can contribute to studies about their distribution.
Conclusion
Having been around for a few millions of years, orcas are now among the world’s most famous aquatic creatures.
They are apex predators in their habitats and rely on complex hunting techniques that allow them to kill a wide range of animals.
But that’s only 1% of the adaptations they’ve acquired over time! Orcas have excellent echolocation skills, are highly intelligent, can protect themselves well, and sleep with half of their brains awake!
Although their species is not considered endangered, orcas are threatened by multiple human-induced factors, such as increased whale watching, a high number of vessels that disturb underwater noises and produce exhaust gases, and others.
That’s why it’s of the essence for us to spread awareness and contribute to conservation efforts!
FAQs
Why is an orca called a killer whale?
Orcas, which are, in fact, part of the dolphin family, are called killer whales because they hunt large whales.
This nickname was initially whale killer.
However, not all orcas specialize in killing whales.
Is an orca faster than a shark?
Orcas can reach swimming speeds of 45–56 kmh (28–35 mph), although they usually travel at 13 kmh (8 mph).
Great white sharks, for instance, have a maximum swimming speed of 40 kmh (25 mph) and can reach 56 kmh (35 mph) for short bursts.
Sources:
- https://en.wikipedia.org/wiki/Orca
- https://uk.whales.org/whales-dolphins/facts-about-orcas/
- https://www.nwf.org/Educational-Resources/Wildlife-Guide/Mammals/Orca
- https://www.fisheries.noaa.gov/species/killer-whale
- https://seaworld.org/animals/all-about/killer-whale/characteristics/
- https://www.whaleresearch.com/about-orcas
- https://www.doc.govt.nz/nature/native-animals/marine-mammals/dolphins/killer-whale-orca/
- https://tethys.pnnl.gov/sites/default/files/publications/Jefferson_et_al_1991.pdf
- https://www.iucnredlist.org/species/15421/50368125
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