Three hearts, blue blood
An octopus has three hearts, and its blood is blue because it carries oxygen with copper, not iron.
Coral reef
Day octopus
Octopus cyanea
A soft-bodied animal with eight arms, a bag-like body and skin that changes colour in a blink.
- Size
- Arms up to 80cm long
- Look for it
- All year round
- Where
- Coral reefs of the Indian and Pacific oceans
Jets after you, arms trailing behind. Move your pointer and see.
When to look
Octopus
Good to know
Six things about the octopus
Brains in its arms
Most of its nerve cells are in its arms, which can taste, feel and partly think for themselves.
A living screen
It changes colour and even skin texture in less than a second, to match rock, weed or coral.
No bones
With no bones, it can pour itself through any gap bigger than its hard beak.
A problem solver
Octopuses can open jars, work through mazes and remember the answer.
A smoke screen
When in danger it squirts a cloud of dark ink and jets away backwards.
The real thing
Photos of the octopus
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Photos are from Wikimedia Commons, used under the free licences shown. They have been resized, and cropped where they appear in link previews.
How to spot one
Look for a neat pile of empty shells outside a hole in the reef: an octopus's rubbish heap. The owner is usually watching you from inside.
How to help
Octopuses are not endangered, but they are clever animals that feel pain. Many people think farming them should not be allowed.
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