(16-02-10) It is known as the killer whale, but it is neither a whale nor a killer. The orca forms part of the dolphins family and, because of its size and voracity, it is associated to the biggest cetaceans. It is a cosmopolitan species that can be found in all seas, especially in high latitudes.

    Fishermen and whale hunters in the 18 century named the orca “killer whale”. At that time all that was known of this dolphin, associated to whales for its large size (it can reach up to 10 m.) is that it behaved as a large predator, as a voracious whale that even attacked other bigger cetaceans.

    Exactly, the Orcinus orca is a great predator and devastates everything it finds in seas. Its diet consists of hundreds of known species; it is the most diverse among cetaceans: all sized-fishes, squids, marine mammals (porpoises specially), seals, gulls, penguins, turtles and even blue whales...

    This feeding varies depending on the population. Hunting in groups is common and so it is the development of intentional stranding to capture some of their prey, techniques that calves learn from adults. It does not have natural predators, neither the white shark dare to attack an orca. As we will see later, just human being is its predator. However, we don’t appear in its wide menu. There is not a single case recorded of an orca eating a human being so far.

    It is a playful animal, although human eye see it as cruel. They always travel in groups and when they have to get food they hunt perfectly organized. Frequently, they have been seen attacking seal colonies and playing with them as if they were balls, throwing them by air from one orca to another one. A game that ends after some throwing with the prey in the stomach of one of the players, which eat in order.

FAMILIAR GROUPS THAT LAST THE WHOLE LIFE

    Studies carried out in the North Atlantic coasts have shown that orcas form social groups very active that last the whole life. Females can live up to 50 years and males to 30, and they use to form compact groups of 10 to 40 specimens. They are very curious to ships and at certain times of year, when they are well fed, they are very social and exhibitionist.

    This species, the largest within dolphins, has a robust body whose colour pattern is characteristic and predominantly black, except for the abdomen, a white mark near the eye and another one behind the dorsal fin which is greyish white and its named “saddle patch”.

    Its head is conical and it does not have a well defined beak. It has 10 to 14 pairs of teeth in both jaws. Its pectoral fins are big and rounded, they have a dorsal fin in the middle of the back in front of the saddle patch whose development changes over time.

    They have a marked sexual dimorphism, where the male has pectoral fins and fluke very developed, and a dorsal fin that starts to develop when they reach sexual maturity and become triangular, while in females and juvenile it is falcate and smaller.

    The world population of orcas seems to consist of specialized or differentiated subpopulations both in morphology and behaviour, ecology and genetics, to adapt to different environmental conditions. This has led many researchers to think of the existence of races, ecotypes, subspecies and even different species.

GROUPS LED BY THE OLDEST FEMALE

    Orcas are characterised for having a social structure quite complex. They live all their lives within a familiar group led by the oldest female, which in general has some grade of relationship to each specimen, and they have developed a dialect that changes according to the different groups, although it has basic elements that all of them share (see box).

    Some of the threats that this species has to face, as in most of the cases of cetaceans, are related to habitat destruction, overfishing and pollution. But currently, two of the main important threats are death because of encounters with fishing gear and, over all, its capture to show them to the public.

    It is demonstrated that this is a species that, clearly, fails to adapt to life in captivity. Captured specimens for aquaria live an average of only five and a half years, unlike animals that remain in their natural environment which multiply by ten their life expectancy.

    The “good character” and curiosity of the misnamed killer whale is an advantage for captures and confinements; even its kindly and gentle nature allows that it soon interacts with their trainers. The best and most applauded performances are usually those which have confined orcas.

    As we can see in the box, an exceptional case, which breaks the rule, is that of Keiko, the orca which starred in "Free Willy", which died of pneumonia after being returned to the wild. The success of the movie sparked a global movement for its liberation, and popular pressure ended with Willy in the Gulf of Taknara, the Norwegian west coast, near where it was captured by a fisherman when it was 2 years old, in 1979. It had spent 20 years in captivity, and only survived cinco in its retirement, where it was guarded and nurtured.

Text: Guadalupe Romero