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How does an octopus change colour – and how does it choose? Marthy
Octopuses, and their close relatives cuttlefish and squid, all have the amazing ability to change the colour of their skin. This helps them to camouflage themselves in their environment, or even pretend to be another more dangerous animal, like a lion fish.
An octopus’s skin is covered with special cells called chromatophores. These tiny, squishy sacs are less than half a millimetre wide and filled with different colours of ink. When the octopus squeezes the sacs, they grow bigger, showing more of a particular colour on the skin of the octopus. If they stop squishing them, the sacs shrink back, showing less of this colour. The chromatophores are directly connected to the octopus’s brain, allowing it to
control each one individually, so that it can quickly change colour and display complex patterns. Some species of octopus even have bumps on their skin that can change size, adding to their camouflage skills.
When it comes to knowing which colour is best to choose, octopuses use their excellent eyesight, as well as light-detecting cells across their bodies. These sense their environment and allow them to quickly work out which colour or pattern is most useful.