Orcinus orca

The average length of adult males is 8 meters, and the maximum record is 9.75 meters. The weight of females is 3.8 tons, and the weight of males is 5.5 tons. The average length of females is 7 meters, and the maximum length is 8.5 meters. There is obvious sexual dimorphism in body size, flipper size and dorsal fin height. The average weight and weight of females are slightly smaller than those of males. The dorsal fin of adult males is upright and can reach 1.0-1.8 meters in height. The dorsal fin of females is obviously sickle-shaped and less than 0.7 meters in height. The fin is bent to the right or left side.
The condylar base of the adult skull can be up to 1000 mm long. The width of the two premaxillae in front of the preorbital concavity is less than the width of the snout. The two pterygoids are far apart. The temporal fossa is large. The mandible is relatively short. It has an inconspicuous beak. The oval flippers are located in the front 1/4 of the total body length. The fl

The habitat of killer whales is mainly polar and temperate waters. They are widely distributed in the waters of the world, such as the North Sea of ​​Japan and Iceland. There seems to be no obvious restrictions on water temperature, depth and other factors. They usually prefer a depth of 20-60 meters, and can also visit shallow waters along the coastline or dive to 300 meters to find food. They have a fairly high habitat density in high latitudes, especially in waters with abundant prey. Killer whales can be divided into different ecotypes according to their habitats and habits. Killer whales of different ecotypes have slightly different appearances and different habits.

Killer Whale is the largest species in the dolphin family, and there is no subspecies.

Killer whales are highly social and have a complex social structure. They like to live in groups, ranging from small groups of 2-3 to large groups of 40-50. There are even reports of hundreds of individuals in a group, but this is only a temporary connection between a group of smaller groups. Individuals in a group are generally multiple generations of related individuals, consisting of about 20% mature males, 20% calves, and 60% females and immature males. Killer whales have limited dispersal from their mother group, and calves are always part of the mother group. Individuals in the group swim within 100 meters of each other and coordinate their activities. They may share prey and rarely leave the group for more than a few hours.

Killer whales teach group members to hunt and raise offspring through apprentices. They always stay quietly on the surface of the water for 2-3 hours a day, because their lungs are filled with enough air, so they can float safely on the sea, revealing their huge dorsal fins. The pectoral fins of group members often keep in contact, showing affection and solidarity. If a member of the group is injured or loses consciousness due to an accident, other members will come to help, using their bodies or heads to support the group so that it can continue to float on the sea. Even when sleeping, they huddle together to take care of each other and maintain a certain degree of wakefulness. They travel and eat together, use the group as a social organization, rest in a large family, and rely on each other to survive and grow up.

Killer whales can swim up to 160 kilometers a day. They often jump into the waves, float and peek, or slap the water with their tail or pectoral fins. In the shallow waters of the bay, they also like to use the notch on their tail to hook and pull seaweed, making a "whooshing" sound. Soon, their bodies are covered with translucent seaweed. Killer whales can swim at a maximum speed of 55 kilometers per hour and can hold their breath for about 17 minutes. When the air around them is cool, their low, branch-like jets can usually be seen. The water column of killer whales is slanted, thick and short, unlike the thin and tall baleen whales. Their response to ships varies from indifference to curiosity. Occasionally, groups are stranded, and groups are sometimes trapped in tide pools or bays. In the Arctic and Antarctic waters, fast-moving ice floes caused by wind are a major problem for killer whales, sometimes forcing them to stay in small narrow areas of water at the surface for quite a long time.

Killer whales use three types of vocalizations: whistles, discrete calls, and clicks. Voices are used for communication and navigation. When communicating between groups, they use discrete calls and whistles. Each small group has a discrete dialect that sounds slightly different from other small groups. This dialect can remain unchanged in the group for up to six generations. Clicks seem to be used only for echolocation. Killer whales do have good eyesight, but in dark water, their eyesight does not help them catch prey or navigate. Like other toothed whales, killer whales use sonar to sense their aquatic environment. Killer whales can not only emit ultrasonic waves to find schools of fish through echoes, but also use ultrasonic waves to determine the size of the school of fish and the direction of their swimming. This ability is very important for carnivores living in the ocean. It is very dark under the sea, and it is difficult to see distant predators in this environment.

The social form of killer whales is matriarchal, and the choice of mating partners is more complicated. It is not determined by the power of males: for example, the patriarch of a whale group can sometimes live to 80 years old, and there are also examples of mating in their later years. The objects they choose to mate are generally older males within the whale group. Scientists are not clear about the criteria for female whales to choose their partners. They rarely observe the scene of mating. They only know that there is a mother, but not where the father is. There is no father-son or father-daughter relationship in a whale group. The male's responsibility is to go out and find food, and then lead the whale group to hunt collectively. The division of labor is clear, and there is no high or low status; the mother-daughter and mother-son relationship is very stable, a lifelong relationship, and generally will not leave the group. The reason for the emergence of orphans is usually injury or getting lost. When the group is too large, it will "split up" and form a new group.

Sometimes killer whales hunt in groups. They use ultrasound waves emitted from the forehead (the part used by dolphins to produce echolocation, which will focus the sound into a beam) to communicate and contact each other and plan tactics. They will also work together to gather the fish into a large ball, and then take turns to drill into it to feed. When hunting fur seals, killer whales will observe the cracks and ditches that lead directly to the beach before high tide. When the tide is high, the ditches will be filled with water and form a shallow area on the beach. At this time, killer whales will rush onto the beach along the ditches and deliberately strand themselves to take the opportunity to prey on fur seals or sea lions. Sometimes a killer whale will show its large dorsal fin to attract the attention of the fur seal group. At this time, another killer whale will quietly approach and kill the fur seal. When the prey escapes, another killer whale will rush up to take over the prey. Similarly, killer whales sometimes float on the sea surface with their abdomens facing up, motionless, much like a dead body. When squid, seabirds, sea beasts, etc. approach it, it suddenly turns over and opens its big mouth to eat them. Sometimes it will use its tail to knock out prey, such as sea lions, and then prey.

Killer whales eat an average of 45 kilograms of food per day, but in fact they can eat much more than this. They swallow small prey whole, but often tear up larger prey before eating. Food includes fish, other cetaceans, pinnipeds, sea otters, birds, reptiles, and cephalopods. Of the 362 stomachs collected from killer whales in the Antarctic, 217 contained fish, 75 contained remnants of minke whales, 35 contained pinnipeds, and 35 contained cephalopods.

Killer whales have a very developed brain and a powerful body, which allows these highly intelligent animals to chase and kill many of the top predators in the ocean. They often hunt in groups and use coordinated social behaviors and communication to hunt prey larger than themselves, such as large whales. Some members of the killer whale family have at least nine shark delicacies on their menu, including the great white and mako sharks that scare many animals.

Killer whales are polygamous. In the Northwest Pacific, most mate between May and July. In the Northeast Pacific, they mostly give birth between October and March. Adult males are 5.2-6.2 meters long, and adult females are 4.6-5.4 meters long. Females give birth to their first viable calf between 11-16 years old. Killer whales can mate year-round, and they can reproduce whenever female animals enter estrus, which can happen several times a year. However, most reproduction occurs in the summer, and killer whales are usually born in the fall. Females reach sexual maturity between 6 and 10 years old. Males reach sexual maturity between 10 and 13 years old. Female killer whales begin mating at 14-15 years old. The youngest female on record was 11 years old. Females give birth to a calf every 6-10 years, and they stop reproducing around 40 years old. Generally, 4-6 offspring are produced in 25 years. Killer whales only give birth to one calf at a time, and occasionally twins. Before weaning, newborn calves are 2-2.4 meters long and weigh about 136 kilograms at birth. The smallest newborn calf recorded in the North Pacific was 2.28 meters long. Calves need to suckle for about a year. Some studies show that almost half of all newborn calves die before their first birthday.

Historically, killer whales have been directly hunted in Japan, Norway, and the former Soviet Union. There is no fishery that directly hunts killer whales. The rise of killer whale performances in aquariums in the 1960s has led to the rapid development of the live capture fishery. With the development of killer whale breeding technology in captivity, the demand for live capture has decreased. Killer whales are not in danger of extinction, but human hunting may have caused the decline of populations in some areas. As of 2017, there are an estimated 70,000 killer whales in Antarctica (2017), about 8,500 killer whales in the tropical waters of the eastern Pacific, at least 850 in Alaskan waters, and possibly more than 2,000 off the coast of Japan. In summer, there are about 8,000 killer whales distributed in Antarctic waters, and other areas of the distribution range may be between hundreds and thousands. Currently, whalers in Japan, Indonesia, Greenland, and the West Indies continue to catch killer whales. Although the number of kills is small, it may have a considerable impact on local populations.

Killer whales have no predators other than humans. There are several potential sources of natural mortality that may affect killer whales: being trapped in coastal lagoons or narrow bays, accidental strandings, disease, parasites, biotoxins, and starvation. However, it cannot be ruled out that human factors may make killer whales more susceptible to natural mortality. For example, strong noise disturbances may cause animals to strand. In these cases, the most direct cause of death is stranding, which is a natural cause of death, but the death will ultimately be human-caused. From persistent organic pollutants (POPs) to drug-resistant bacteria and exotic species, there are many chemical and biological pollutants that may directly or indirectly affect resident whales.

Listed in the IUCN Red List of Threatened Species in 2017 ver 3.1 - Data Deficient (DD).

Listed in Appendix I, II and III of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) 2019 version Appendix II.

Listed in Appendix I and II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS), and the eastern North Atlantic and ENP populations are included in Appendix II of CMS.

Listed in China's National List of Key Protected Wildlife (February 5, 2021) at Level II.

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