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Why do some animals have more than two eyes? © Getty Images

Why do some animals need more than two eyes?

Asked by: Fatima, Manchester

Some fish, amphibians and reptiles have a simple third eye on top of the head. This patch of light-sensitive cells doesn’t add much to their vision, but it helps some animals to regulate their body temperature and navigate via the Sun’s light.


Invertebrates often have more than two eyes. Most spiders, for example, have eight eyes that help them spot and hunt prey.

A group of marine molluscs called chitons do even better – they have hundreds of eyes dotted all over the armoured plates that cover their bodies. This boosts their field of view and helps them detect predators.

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Helen Pilcher
Helen PilcherScience writer, presenter and performer.

Helen Pilcher is a tea-drinking, biscuit-nibbling science and comedy writer, with a PhD in cell biology.


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