Meet the cuttlefish (baby & adult), one of the brainiest, most bizarre animals in the ocean.

A bizarre, alien-like creature like no other. It’s an animal with eight sucker-covered arms growing out of its head, three hearts pumping its blue-green blood, and a doughnut-shaped brain. It has the ability to change its color and shape to blend in with seaweed and rocks, and it has a knack for switching on electrifying light shows that dazzle its prey.

Perhaps most surprising of all, this animal is quite intelligent, with a highly complex brain.


Cuttlefish are not above acknowledging the presence of lesser species such as humans, as divers around the world will testify. When they come across cuttlefish, some divers offer a greeting, the two-fingered “peace” sign. In what is surely one of the few cross-species salutations in the natural world, the cuttlefish reciprocates by lifting two of its arms. This message of peace is actually quite the opposite – a startle response to what the cuttlefish perceives as a threat. Sticking two fingers up at divers or predators is a secondary level of defense which cuttlefish use on the rare occasions that their camouflage fails.


Cuttlefish have jet propulsion keep buoyancy in the same way that submarines do. Cuttlefish can escape from enemies by using rocket propulsion. Water is squeezed down their body (mantle) into a special tubular muscle (siphon) that controls the direction as they are propelled backwards for a short distance.

Oh, it shoots jets of ink as well! Cuttlefish ink was the original sepia which was once used by artists – nowadays replaced mostly with synthetic sepia. The ink is used as a defense to confuse predators and allow the cuttlefish time to escape.

Cuttlefish can change color in mere seconds. They change color using a series of special skin cells, chromatophores, iridophores and leucophores, which reflect light in all sorts of colors.

Diver with cuttlefish. Photo by Bill Sarro
Diver with cuttlefish. Photo by Bill Sarro

Cuttle fish can make themselves completely invisible: Not only do they reflect colors, they are able to merge almost completely with the seafloor

Cuttlefish don’t have a tail: They have a fin all the way around their body instead of tail fins, like squid, and they use this fin to control movement.

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Cuttlefish bone is filled with gas! Cuttle-bone (the things you see in bird cages) has small chambers and like a submarine, filling or releasing the gas in them controls the cuttlefish’s buoyancy.

The cuttlefish eye is shaped like a W. The unique shape of the pupils plays a part in the most highly developed eyes of any animal. They allow the cuttlefish to perceive light polarization and completely reshape their eyes to focus. They also really do have the proverbial eyes in the back of the head, with a second spot on the fovea which allows them to see backwards.

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April 4, 2016 |

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