The common cuttlefish: camouflage, hypnotise, strike!

By Matt van Onselen / 3 May 2011

Amidst the sand and mud on the sea beds of many of our surrounding waters lies a camouflaged creature that will hypnotise you with an entrancing light display. It can change colours, transform its appearance, and strike before you’ve had a chance to catch up. This is the common cuttlefish, though there is nothing “common” about it.

As in Times Square or Piccadilly Circus, massive, flashing lights can put you into some sort of a trance. But imagine you are in an open space – walking in the desert at night, for example – when one of those huge Coca-cola or McDonald’s neon signs flies above you, hovering, flashing, capturing your attention. As you stand there open-mouthed, you momentarily forget about your surroundings – and your safety.

We can only guess, but this is what it must be like to be a crab at the bottom of the sea as common cuttlefish floats overhead. The name is misleading – it’s not actually a fish, but a mollusc. It’s related to the squid and the octopus, and this is evident when comparing its looks (squid-like) and its camouflage ability (octopuses can change colour).

The common cuttlefish can change its colour, opacity and how much it reflects light. But it does this in ways that only science fiction writers could envisage. Like the neon sign in the dark desert, the common cuttlefish can activate its own light show, sending pulsating waves repetitively and hypnotically over its body, hoping that a crab on the sea bed is captivated by the nameless neon advertisement above them.

Just then, the extremely long tongue of the cuttlefish bursts through the water at lightning-fast speed, and instantly nails the mesmerised crab. One or two chomps and it’s goodnight, crab.

You can watch an example of this incredible drama unfold below.

In addition to crabs, the common cuttlefish also eats shrimp, certain fish, and they even eat each other! It’s very lucky for us that this hypnotising, long-tongued cannibal is only 50 centimetres long, and will never be found whilst wandering through the desert at night!