One of the ocean’s magnificent creatures is the orca. This amazing animal can be fierce and can be found all over the world. Let’s find out what else is cool about him.
1. Killer whale
Orcas, also called killer whales, aren’t whales at all – they’re actually dolphins. They form part of the cetacean family, which includes whales and porpoises. The misleading name comes from the fact that they were once called ‘whale killers’ by sailors who saw them attack whales, and over time it became killer whale.
2. Big brain
Orcas have the second-largest brain of all marine mammals (the sperm whale has the biggest). They are very intelligent and have shown keen problem-solving ability. For instance, Alaskan orcas steal fish from fishermen’s longlines, and can find ways around every new trick the fishermen try to stop them.
3. Marine mammal
Like other cetaceans, orcas are mammals. This means they are warm-blooded, produce milk to suckle their young and need to breathe air. They come up to take a breath every few minutes – more often if they are moving faster and less if they are resting. They can hold their breath for about 12 minutes, which they do when diving deep. They can also slow their heartbeat when diving, which allows them to use up less oxygen.
4. Top of the food chain
There are no animals who hunt orcas, which makes these large mammals apex predators. However, they aren’t fussy with food and prey on everything from fish, sea birds and seals to sharks, other dolphins and whales. They have even been known to grab land-dwelling mammals who make the mistake of going for a swim, like moose and polar bears.
5. Versatile hunter
Because of their intelligence, orcas are experts at catching this wide variety of prey. They have excellent hunting techniques that they pass down through generations by teaching their young. On the Antarctic islands, mothers will even push their young onto the ice to teach them how to beach and catch seals, and pull them back into the water if they get stranded.
For bigger prey like whales, orcas hunt together in a group, separating young or weak prey (sometimes even healthy adults) and chasing them until they tire out, or preventing them from surfacing to breathe so they drown. One clever orca in captivity learned to regurgitate the fish fed to him by his keepers, which attracted hungry sea birds he could catch.
Orcas are the largest members of the dolphin family. When they are born they weigh about 180kg, increasing in size to a length of up to 9m and a weight of up to 6 tonnes. The largest orca on record was 9.8m and over 10 tonnes. In the wild, females can reach ages of up to 90, and males of up to 60.
7. Cultural creatures
Although orcas haven’t been divided into subspecies, they have been divided into types. Each type has different genetics and its own ‘culture’. This includes different social behaviour, prey, habitats, appearances and vocalisations. One of these types is called ‘resident orcas’. They eat fish and squid, and live in complex family units called matrilines. These families can consist of as many as four generations: grandmothers, mothers and daughters with their young. In these units, the young never leave their mother, not even the males. Closely related matrilines form loose groups called pods. Another type is called ‘transient orcas’. They hunt marine mammals (other dolphins and whales) and live in smaller groups of two to six.
To communicate with one another, orcas use vocalisations consisting of clicks, whistles and pulsed calls. Every pod’s vocalisations sound slightly different, allowing them to recognise one another. A pod’s unique set of vocalisations is called their dialect.
These animals’ massive dorsal fins reach up to 2m, with males having larger and pointier ones than females. The fins get quite a few scratches over time (especially when they hunt larger fish with big teeth like sharks). This makes each orca’s dorsal fin unique, allowing the scientists studying them to tell them apart. Orcas also have unique patches of differently coloured skin right behind the dorsal fin, called a saddle patch. Although captive whales, like Keiko who played the orca in Free Willy, have dorsal fins that flop down, this is usually because of the stress of captivity; orcas in the wild all have upright fins.
9. Super senses
Orcas have good eyesight and hearing, but also use echolocation (making a sound and listening for its echo) to locate objects or prey around them.
10. All around the world
They are very widely distributed, and can be found anywhere in the oceans, from the icy polar regions to the warmer equator. However, they do have a preference for colder water.