Are killer whales habitat and behavior linked?



by LORENZO CIOTTI

Are killer whales habitat and behavior linked?

The habitat of the orca is widespread in all the seas and oceans of the world and lives both in the abyss and in the shallows near the coasts, sometimes even reaching the mouths of some rivers. Normally, however, the orca prefers to live in both arctic and antarctic cold waters where, in summer, it hunts among the ice floes.

Only a few populations migrate to the equator in the summer, much like the gray whales that migrate near the US coast. Sightings in the Mediterranean Sea are quite rare. Several killer whales have been sighted in the Ligurian Sea near Pra 'in December 2019; at first it was thought they came from a herd of killer whales that have lived for some time near the Strait of Gibraltar, but then it was understood that it was a known group registered in Iceland.

Researchers from the Orca Guardians Iceland association exchanged their data with Ligurian biologists and it was discovered from the comparison of the fins and other details, that these are specimens studied in 2017. It is difficult to estimate the number of individuals in the world, according to the International Union for the Conservation of Nature there are no precise data: one of the estimates considered most reliable is about 50,000 specimens.

Does their habitat influence their behavior?

The whale normally lives in groups consisting of the female, her young, sterile older females and an adult male. This is a basic matrilineal family also called pod. All the members of this family communicate with each other through sounds of various kinds and each pod has its own language.

The orca has a specific organ placed on its forehead that it can use as a sonar. All the objects hit by the sound waves send back an echo that the killer whales perceive as an animal or a rock to be avoided.
Killer whales are highly social animals and hunting involves the whole group.

The type of prey depends on the habits of the group: populations called residents are sedentary and feed mainly on fish. The transients, on the other hand, mainly hunt marine mammals such as seals, sea lions and even whales.

During the hunt, the transients become very silent, to surprise their prey, but the attack is well coordinated and each individual has a specific role. Penguins and other sea birds are also part of their diet. In 1988 a new type of population called offshore was discovered in the open sea, which travels in groups of about 60 specimens but which can reach 200, genetically distinguished from transients and residents.

It is little known, although Offshore females are recognized by having stripes surrounding their fins. If the two populations of residents and transients frequent the same marine environment, they avoid mutual contacts.
The orca is not considered a threat to humans in nature: the only recorded attacks occurred in captivity and in particular stressful conditions.

In February 2010, Sea World Florida's orca Tilikum bit and killed one of its trainers during a show. Both with this orca and with others similar events had already happened before.