Why do some animals need more than two eyes?

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.

Read more:

• Do any mammals other than humans have ‘whites of the eyes’?
• Why don’t prey animals have eyes in the backs of their heads?
• Why do some birds hop and others walk?
• Why do some ants have wings?

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from... sciencefocus.com