There are "mama's boys" and "community bulls", killer whales may not be as simple as you think!

Among the whales and dolphins

Killer whales are undoubtedly special.

On the one hand, they have a black and white color scheme like a panda.

The appearance is very pleasing, earning the nickname "Fat Tiger"

On the other hand, they are also the

The well-deserved king

A deadly killer that scares other marine life

Killer whale ecotypes Source: References

As a nearly universal species, killer whales have long been considered a single species, Orcinus orca, but growing evidence suggests there may be more than one species.

Tiger of the Sea

One divided into three

Just recently, a group of scientists led by Phillip Morin, a geneticist at the National Oceanic and Atmospheric Administration (NOAA), published a paper in the journal Royal Society Open Science, dividing the original North Pacific killer whales into three independent species.

As early as the 1970s, after years of field investigations, Canadian marine biologist Michael Bigg was surprised to find that killer whales in the North Pacific can be divided into three very different ecotypes based on dietary preferences, social structure, acoustic and physical characteristics, and genetic differences: transient, resident, and pelagic.

Three killer whale ecotypes in the North Pacific

Image source: Southern Resident Orca Recovery

Chinese translation: The author

However, new research results show that** these three types of killer whales are not just different in lifestyle, but belong to completely different species.** Especially among the killer whales, the transient type and the resident type are the most distantly related to each other, and their divergence time is close to that of polar bears and brown bears.

Time of genetic differentiation within each type of killer whale

Source: References Chinese translation: Author

**Although the distribution of transient and resident killer whales overlaps, they have almost no intersection and interaction,** which can be described as "minority". Even if transient killer whales break into the territory of resident killer whales, they may be expelled by the larger resident killer whales. Hybridization is only possible in artificial breeding environments such as oceanariums.

The Fisherman, the Butcher and the Hermit

In most people's eyes, killer whales in all oceans look almost the same, all white and black, with round bodies and black dorsal fins that tower out of the water like sharks. But if you look closely, you can still find differences between them:

**In terms of physical characteristics,** the dorsal fin of the transient killer whale is generally sharper and straighter, while the dorsal fin of the resident killer whale is relatively rounded and curved. In addition, the average size of the transient killer whale is relatively larger than that of the resident killer whale. The white saddle spots on the back of the resident killer whale have small black spots, while the dorsal fin of the ocean-going killer whale is narrower, the tip is rounder, the color of the saddle spot is lighter, and the body size is also the smallest of the three.

A comparison of top views of a transient (left) and resident (right) killer whale.

Source: References

In addition to these differences in appearance, the three are very different in their dietary preferences, social structures and even calls, just like a fisherman, a butcher and a hermit.

When it comes to filling their stomachs, resident killer whales are professional fish eaters. Except for the Alaskan population, which eats a variety of fish, the rest of them almost only eat salmon. Because these fish are often only distributed in specific waters, they also stick to their own one-third of an acre.

Resident killer whales Image source: Xplore Our Planet

Resident killer whales are also typical matriarchal clans, with strong cohesion among members, and offspring will live with their mothers for life. In other words, male resident killer whales are "mama's boys", usually foraging for food in their own group under the protection of their old mothers, and only leave the group for a short time when they reach the age of "walking marriage" to mate with females in other groups.

Although transient killer whales (commonly known as "beagle killer whales") are also matriarchal, their group size is generally very small, with an average of only 3 to 7 individuals, and some individuals will leave their original group after entering adulthood. **They are well-deserved **** "wolves of the sea",** specializing in feeding on marine mammals such as seals, sea lions, porpoises, dolphins and some baleen whales.

Passenger killer whales Image source: Xplore Our Planet

**Eating habits also determine group culture. The calls of transient killer whales are far less noisy than those of resident killer whales. **This is because resident killer whales prefer to use echolocation to hunt, while transient killer whales tend to approach prey in stealth. Echolocation is only sometimes used to locate and lock escaped prey, reducing calls to hide their whereabouts.

Acoustic characteristics of three species of killer whales

Source: References Chinese translation: Author

In addition, the skull of the transient killer whale is wider and the jaw curve is more curved, which is more suitable for catching large prey. Transient killer whales are also called offshore killer whales. There is evidence that this type of killer whale is particularly fond of preying on various cartilaginous fish, which directly leads to severe wear of their teeth regardless of age.

The differences in teeth between the three species of killer whales due to their different diets

Chinese translation: The author

Ocean-going killer whale

Image source: Xplore Our Planet

Ocean-going killer whales are "social animals". They live in large groups, usually 20-50 individuals. Sometimes, in order to capture super-large prey such as blue whales (Balaenoptera musculus), they will form large groups of 70-100 individuals.

Killer whale family

No more, no less

Let us shift our attention to the North Atlantic on the other side of the earth. More than ten years ago, scientists compared the remains of stranded killer whales and found that their tooth wear could be roughly divided into two categories, which undoubtedly suggested that the killer whales here have two completely different ecotypes.

North Atlantic Type I killer whale (top) and North Atlantic Type II killer whale (bottom)

Image source: Xplore Our Planet

**They are the "omnivorous" North Atlantic Type I killer whales that love to eat fish and seals, and the "specialist" Atlantic Type II killer whales that only eat cetaceans. **The former mainly feeds on fish, and the hard fish scales cause serious wear and tear on their teeth; while the latter's long and sharp teeth are suitable for hunting marine mammals, and their body size is correspondingly larger.

In the vast and changing environment of the ocean-dominated Southern Hemisphere, the degree of ecotype differentiation of killer whales here (centered in Antarctica) is far more obvious than that of killer whales in other waters of the world. Killer whales in the Southern Hemisphere can be roughly divided into four categories: A, B, C, and D.

Four killer whale ecotypes in the Southern Hemisphere

The Antarctic A-type killer whales are the largest of all killer whales. The average length of female whales is 6.4 meters, while the average length of male whales is 7.3 meters, and the largest male whale is as long as 9.2 meters. Their eye spots are large and elongated, almost parallel to the body.

Antarctic Type A killer whale

Image source: Xplore Our Planet

Type A killer whales live in the open waters off the Antarctic and feed primarily on a variety of marine mammals, particularly Antarctic minke whales (Balaenop bonaerensis).

Antarctic Type A killer whales hunting Antarctic minke whales

Image source: orcazine

Antarctic B-type killer whales can be roughly divided into two categories: B1 type killer whales and B2 type killer whales. Their eye spots are the largest of all killer whales and are oval in shape. When these two types of killer whales migrate north in the summer, diatoms attach to their bodies, giving them a unique yellow-brown color.

B1 killer whale (top) and B2 killer whale (bottom)

Image source: Xplore Our Planet

The two species differ significantly in appearance, location and dietary preferences. B1 species live mainly near the loose ice around the Antarctic continent and prefer pinnipeds such as the fur seal (Leptonychotes weddellii).

On the contrary, B2 killer whales are not only half the size of the former, but also prefer to forage in open water, away from floating ice areas. They mainly feed on penguins, especially Gentoo penguins (Pygoscelis papua).

B2 killer whale hunting penguins

Image source: YouTube

The Antarctic C-type killer whale is the smallest known killer whale ecotype , with males less than 6 meters long and females only about 5 meters. Their eye spots are slender and evil, hanging upside down, like a scimitar. Because they usually hide under the thick ice in East Antarctica, they are extremely difficult to observe. There is currently controversy over their diet, but it is certain that Antarctic cod (Dissostichus mawsoni) occupies an important position in their diet.

Antarctic C-type killer whale

Image source: Xplore Our Planet

If it is a big challenge to distinguish other killer whales, then the unique appearance of the Antarctic D-type can definitely make you recognize it at a glance: their eye spots are very small ** and their heads*** are also unusually round. **

Antarctic Type A killer whale (left) and Antarctic Type D killer whale (right)

Image source: CTV

This peculiar killer whale ecotype was not discovered until 1955 on Paraparaumu Beach in New Zealand, and was initially considered a special variant. The distribution area of ​​Type D killer whales is still unclear, but it seems to be only found in the subantarctic waters between 40°S and 60°S, and most sightings occur in the open ocean.

Antarctic D-type killer whale stranded on a beach in 1955

Image source: CTV

The North Pacific killer whale "split" is an opportunity for scientists to start working on the major ecotypes distributed in other waters in the future, and killer whales may be split into 10-15 species. These taxonomic distinctions may have an impact on conservation, allowing experts to make more informed decisions when managing different killer whale populations.

References:

Under a new proposal, our local orcas — resident and Bigg's killer whales — would each become a new species

Revised taxonomy of eastern North Pacific killer whales (Orcinus orca): Bigg's and resident ecotypes deserve species status.

Orcas on the Edge – Killer: It's a Name, Not an Accusation

Observations of a distinctive morphotype of killer whale (Orcinus orca), type D, from subantarctic waters

Genetic Insights into the Biogeography and Evolutionary History of the Killer Whale

https://xploreourplanet.com/sea/types-of-killer-whale

Unlocking the Secrets of the Type D Killer Whale

Types of Killer Whale: Guide to Killer Whale Types

Author: Song Zhe

A lover of animals and linguistics

Love identifying strange animals

Editor: Dong Xiaoxian