An octopus tastes with its arms.

Octopus suckers are lined with receptors that taste what they touch. About two thirds of an octopus's neurons sit in its arms, so each arm can explore and decide on its own.

Truth label: Established. Strong evidence and broad agreement among experts.

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Nine brains, sort of

There is a central brain plus a cluster of nerves in each of the eight arms that acts almost like a mini brain.

Blue blood, three hearts

Their blood uses copper rather than iron to carry oxygen, which turns it blue.

Learn

1. Touch is taste. Special receptors in the suckers detect chemicals, so grabbing food and tasting it happen at once.
2. Distributed thinking. An arm can keep reacting even when cut off from the brain, which is why scientists call octopus intelligence "distributed".

Test yourself

Sources

• Octopus overview

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