The orca is commonly known as the killer whale. In fact, this beautiful creature is the largest dolphin in the dolphin family.

Dolphins and whales are closely related. Orcas were given the name ‘killer whale’ by ancient sailors’ observations of groups of orcas hunting and preying on larger whale species.

Looking at all populations, orcas are generalist eaters, consuming fish, seals and sea lions, dolphins and porpoises, sharks and rays, large whales, cephalopods (octopods and squids), seabirds and more.

Orcas sleep in a very different way to humans. We have a breathing reflex and when we sleep or become unconscious, we continue to breath automatically. Orcas cannot sleep in this way, they have to remain conscious, even when they are sleeping! This is because their breathing is not automatic - they have to actively decide when to breath, and so they must be conscious even when sleeping.

To get around this, orcas only allow one half of their brains to sleep at a time; the other half stays alert enabling them to continue breathing whilst looking out for dangers in the environment. They only close one eye when they sleep; the left eye will be closed when the right half of the brain sleeps, and vice versa.

In orca populations, knowledge is passed down to younger individuals from their elders – what to eat and were to find it, how to catch it, who to avoid, vocalisations and calls unique to pods and family groups, and the distinct ‘accent’ of the population.

More Info: uk.whales.org