Orca: definition and presentation
Do we say a killer whale or an orca?
This is a question that is often asked! The killer whale (Orcinus orca) is a predator: we say “a” killer whale, whether its etymology is Latin – orca, in reference to the divinity of death, Orcus – or Greek – orkunos, the “tuna of the largest species”.
On the other hand, its synonym, the orca, is masculine. The killer whale is also called the killer whale.
What is the family of the killer whale?
The killer whale is a cetacean (large marine mammals with front flippers and a horizontal caudal fin) odontocete: about fifty teeth which makes it the ultimate predator of the seas, at the top of the underwater food chain.
An extraordinary dentition
Teeth all similar, from 12 to 14 cm for a diameter of 2,5 cm, perfectly imbricated in a jaw with the second highest pressure of the animal kingdom: 1000kgs/m2, just behind the crocodile (2000kgs/m2). By comparison, the human jaw is 80kgs/m2.
Its dentition allows the killer whale to crush and shred any species of the animal kingdom. But its intelligence leads it to choose its hunting strategies, with bites of a surgical precision.
A cetacean in black and white
The orca is one of the most easily recognizable cetaceans, with its characteristic black back and white belly, as well as its white spot behind and above the eye. Another characteristic, its dorsal fin in the shape of an isosceles triangle measuring up to two meters high in the male.
Its powerful body is also due to its melon-shaped head and its large and rounded caudal fin.
Size of male and female killer whales
The difference between male and female killer whales is their size, the latter being almost twice as big (between 7 and 9 meters for 5 to 8 tons), but also by their dorsal fin, the female’s not exceeding 90 cm.
A cosmopolitan distribution
In cold waters
The killer whale would be, with Man, the species living in the most different places in the world: if we have the image of the largest specimen living in Antarctica, the killer whale is present in all the seas and oceans of the globe, as long as the coastal waters are cold: from the Arctic and Antarctic regions to the tropical seas.
Thus, the IUCN (International Union for Conservation of Nature) distinguishes nine ecotypes of orcas, according to the three great oceans where they live:
the North Pacific,
the North Atlantic
In Antarctica, the largest of the orcas is found, reputed to eat whales (Minke and blue whales), but also the smallest, called the Ross Sea orca or “dwarf orca”.
In Europe, it is found off the Faroe Islands, Iceland and Norway.
Two orcas showing their nose in frozen waters
Present in the cold waters of the world
Killer whales in the Mediterranean
In the Mediterranean, a group of about forty orcas has been identified near Gibraltar: an exception not so much because of the water temperature, but because of a too poor food supply. Reported since 2020, it would attack boats (but not humans), one of the hypotheses being that their influx would exasperate it.
Food of the killer whale, an exceptional hunter
The adult killer whale needs 60 to 80 kilos of food per day. Contrary to many species, it spends only 10% of its time on food, the majority being devoted to its family life.
To do this, the killer whale develops hunting techniques that are totally targeted according to its prey: if it is a shark, it disorients it so as to destroy it, if it is a whale, it exhausts it by ramming it, biting its pectoral fin and blocking its blowhole. In the presence of smaller fish such as herring, it forms a carousel that traps them in a compact mass near the surface.
It is in the nature of the killer whale to evolve its hunting techniques according to its prey. It is also in their nature, which is rare in the animal kingdom, to transmit them: young orcas have a whole training to capture fish (tuna and salmon) and marine mammals (sea lion, seal, sea lion, porpoise).
A “fine gourmette
The killer whale rarely feeds on its prey whole: it only eats the liver of sharks. And of whale calves, only the tongue. Moreover, the calf is such a choice food that whales protect themselves by nursing their mutual offspring: this is the case of humpback whales, when the gray whale is no longer able to do so.
A matrilineal organization
Ask the grandmother
The orca lives in a group formed by the descendants of the grandmother, the main individual: this matrilineal descent is linked to this rare sense of transmission in the animal kingdom. It is a question of survival: when the grandmother dies, the survival of the group is very fragile, certain hunting techniques requiring an apprenticeship of about twenty years.
But this sense of sociability is also a very strong instinct in this animal, which spends a lot of time playing, caressing each other, communicating by its famous little cries: it is imperative to the physical and mental. These cries are different from one group to another and are used to echolocate and vocalize in the equivalent of dialects.
Another point in common with humans, the killer whale is one of the rare animal species to experience menopause. This stop of reproduction would serve to devote all its energy to the transmission to the following generations.
Sexual maturity and life expectancy
Another strange point in common with Man, the life expectancy of the female is much higher (80 to 90 years) than that of the male (not more than 60 years).
Sexual maturity occurs around 15 years of age, with a gestation period of about 18 months which gives birth to a single orca, which is suckled for two years. Throughout her fecundity (from 15 to 40 years), the female gives birth to an average of five baby killer whales.
And if this animal does not have a sense of couple, incest is taboo!
Efficient from all points of view, the orca would know an evolution of its “cultural” genes. One thing is certain: they react to the mirror test by recognizing themselves, a sign that they are aware of themselves.
Three orcas blowing through their blowholes
What are the predators of killer whales?
The orca is the predator of all, but it has no predator. Only the tail of a sperm whale can be a danger.