Octopuses by Dr Helen Scales

Author:Dr Helen Scales
Language: eng
Format: epub
ISBN: 9781405934909
Publisher: Penguin Books Ltd
Published: 2019-03-06T16:00:00+00:00

Disappearing acts

A decade ago, veteran octopus researcher Roger Hanlon was diving in the Caribbean when something made him scream. He caught the moment on camera: a seaweed-covered rock suddenly reveals its true identity – a large octopus. It blanches white, then takes off in a cloud of ink. It was the fastest, most exquisite example Hanlon had ever seen, and filmed, of an octopus using its colours and texture to hide, then escape.

Mesmerizing displays scintillate across octopuses’ bodies, the most complex camouflage of any animals. It’s another strategy these soft creatures use to avoid being eaten.

Second by second they change their skin’s appearance, an impressive feat made possible by their sophisticated nervous systems. They constantly watch their surroundings and decide which body pattern will work best.

An octopus’s kaleidoscopic colours are produced in layers of skin cells called chromatophores, which are star-shaped and filled with coloured pigment granules. Nerves from the brain directly control muscles that shrink or stretch these skin cells, hiding or revealing colours. Further skin layers combine to produce iridescent colours, with tiny mirror-like particles that reflect and refract light. Muscles also draw the skin surface into lumps and bumps, called papillae, that mimic rough pebbles or tufty seaweeds.

Octopuses often change shape and colour, pretending to be other things, like a rolling stone or a clump of drifting seaweed. The true masters of disguise are the mimic octopuses. They dress up like a host of other animals to confuse predators and pretend they’re more dangerous than they really are. One moment they’re a sea snake, next they’re a venomous lionfish.

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