Photo: Wikimedia Commons
Where and how killer whales live
Killer whales or killer whales are the largest of the dolphins, found almost all over the world’s oceans. In summer, they are frequent visitors to the ice edge in the Arctic, and at the end of the year off the coast of Antarctica (it’s summer there). According to one version, they got an overly bloodthirsty name due to a misunderstanding. Their Spanish name “killer whale” has been translated into English as killer whale.
For more than 30 million years, ancient whales were divided into toothed and baleen whales. Baleen whales have lost their teeth, and on their upper jaw they have horn plates — baleen, with which they filter small invertebrates and fish. Toothed whales have preserved their teeth and still use them. They learned how to use ultrasound echolocation to navigate and find prey.
Killer whales apparently appeared about 10 million years ago, shortly after the separation of the dolphin family from other toothed whales. Presumably, about 350 thousand years ago, they settled almost all over the planet and divided into several types, which differ in appearance and lifestyle.
Adult male killer whales are on average up to 8 meters long, while females are up to 7 meters; they weigh about 6-8 tons. There are also larger individuals. Most killer whales have an elegant black and white coloration: a black back with white spots behind the eyes, a white or gray saddle spot behind the dorsal fin and a white belly. Some Antarctic populations have changed color from white to yellowish.
Scientists consider the abundance of diatoms in their habitats, which form a film on the body of dolphins, to be a possible reason. Individuals of different types differ from each other in the size and shape of the dorsal fin, scratches and markings on it, and the shape and color of the saddle spot. By these signs, zoologists recognize different types of killer whales.
Populations of different types either live mostly sedentary within hundreds of miles of the coast and migrate to coastal waters or live in the open ocean. Sedentary and migratory killer whales communicate in different dialects and do not mate with each other. According to genetic data, killer whales from the Pacific North were their ancestors.
Killer whales are social animals and live in complex multi—level groups. The first level is a family group consisting of a female matriarch, her sons, daughters, and “grandchildren.” Given that females become sexually mature after a few years, they breed up to 40 years. Four generations can belong to one family. Killer whales live for several decades, only some live to be 90 years old.
Related families come together in packs of 10-50 animals that spend at least half the time together. It is worth noting that males very rarely mate with females from their pack. Several packs can form a clan, the members of which communicate with each other in the same dialect. The fourth level, the community, is formed if clans periodically mix with each other.
Migrating, “transit” killer whales have a simpler social structure. They have fewer families and packs, and their members quite often separate from the group for a long time or forever. Sometimes males, after leaving their family, live alone, and join a pack only for a short time to mate.
The company of their own kind is very important for killer whales. In particular, if males are “isolated” from their family, they die before their more social relatives. And it is not the family that has a greater influence on the life expectancy of females, but the pack, although scientists have not yet found out why this is so. Interestingly, the female matriarch increases the lifespan of her offspring.
Like other social animals, killer whales communicate with each other. They “talk” using a set of clicks, whistles, and screams, which they use not only for communication and navigation, but also to find prey. Killer whales teach their cubs the “family” dialect, repeatedly repeating the sounds in the first weeks after the birth of the baby.
What do killer whales eat?
Photo: By le_osuna, Flickr.com
The diet of killer whales includes many species of mammals, birds, fish and cephalopods. Depending on the place of residence, dolphins specialize in a particular prey. Some feed only on fish, others on seals and cetaceans, while others hunt birds, such as penguins. It is clear that hunting strategies also change depending on preferences.
For example, killer whales that live off the coast of Norway and feed almost exclusively on herring, hunt it together, in packs. They surround the shoal and, swimming around it, knock the fish into a tight ball. To disorient and blind the fish, killer whales beat the water with their tails and spin, showing a white belly, then a black back.
Another North Atlantic population feeds on pinnipeds. Killer whales hunt them in families. They swim along the coast in anticipation of prey, or guard it near “kindergartens” where the seals give birth to cubs. Seals trying to escape on small ice floes are doused with water by killer whales, washing them into the sea.
Pinnipeds, in turn, escape from killer whales in shallow water, where they do not like to swim. Seals have learned to recognize the sounds that orcas emit, and they will know about their approach 2-3 days earlier than humans. Moreover, they distinguish between
dialects of different populations do not respond to the “call signs” of groups of fish-eating killer whales familiar to them.
Killer whales are predators, they hunt seals and even sharks, but they practically do not attack humans. Killer whales also hunt cetaceans of other species. According to the stories of the Canadian Inuit, dolphins hunt bowhead whales, which are much larger than them, narwhals and belugas.
A team of dolphins drowns a bowhead whale, preventing it from rising to the surface, or closes its blowhole. Killer whales can beat a whale with their tail, possibly trying to break its ribs and actually eating it alive by biting its belly. They do the same with narwhals and belugas, but they try to attack female and baby narwhals, and not touch the males, who can injure or kill them with their horns.
Contrary to popular belief, which is supported by the name, killer whales rarely attack humans in the wild. So far, there have been several cases of killer whales trying to catch a man on an ice floe, probably mistaking him for prey. Not a single incident resulted in any deaths.
By Ekaterina Rusakova
