UNDER THE SEA

 Hello ladies and gents this is the Viking telling you that today we are talking about 

ORCAS (KILLER WHALES)

Orcas (also known as killer whales) are marine mammals. They belong to the sub-order of toothed whales (known as odontocetes) but are also the largest member of the dolphin family.

Orcas are incredibly popular as they are the most widely distributed of all whales and dolphins, found in every single ocean. They are very familiar with their black and white colouring but actually, depending on where they live, have very different appearances, behaviour, ways of communicating and diet! Find out some amazing facts about orcas and their incredible lives.

Ten facts about orcas (killer whales)

1. Orcas are the largest member of the dolphin family.
2. A male orca can be nearly ten metres in length and weight 10,000kg.
3. Orcas are highly intelligent and able to coordinate hunting tactics.
4. Female orcas are thought to live to 80 years of age or more.
5. The dorsal fin of a male orca is up to two metres tall.
6. Orcas are extremely fast swimmers and have been recorded at speeds of up to 54kph.
7. A wild orca pod can cover over 160 kilometres a day, foraging and socialising.
8. They were give the name "killer whale" by ancient sailors who saw them preying on large whales.
9. Orcas are still hunted in some countries, such as Greenland.
10. Different kinds of orcas are called "ecotypes". They hunt specific prey and live in different parts of the world.

Why are orcas called 'killer whales' when they are dolphins?

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. They called orcas asesina ballenas, or ‘whale killer’ – a term that was eventually flipped around to the easier ‘killer whale’. Their Latin name, Orcinus orca, also reflects this observation of orcas feeding on large whales. Orcinus translates to ‘of the kingdom of the dead,’ and orca refers to a kind of whale. We know that orcas are top predators, yes, but not the vicious ‘whale killers’ that the ancient mariners thought them to be. If you could give orcas another name, what would you call them?

What do orcas eat?

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. However, some orcas specialise on specific prey, and it turns out orcas are picky eaters! Once they’ve learned what their family eats, they aren’t likely to switch diets.

How do orcas sleep?

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. If like us, orcas went into a deep unconscious sleep, they would stop breathing and suffocate or drown.

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. This type of sleep is known as unihemispheric sleep as only one brain hemisphere sleeps at a time. Orcas periodically alternate which side is sleeping so that they can get the rest they need without ever losing consciousness. When sleeping, orcas swim very slowly and steadily, close to the surface.

And as always have a chilled day from the Viking