Hooded Cuttlefish, Sepia prashadi

This intelligent mollusc has almost incredible powers of mimicry. It can control the colour, patterning and texture of its skin to perfectly match its surroundings. And not just from above, the camouflage works from whichever angle it is observed. From birth, cuttlefish can display at least 13 type of body pattern, made up from over 30 different components. A recent study suggested that the military can learn from the cuttlefish and create "invisible suits".

Hooded Cuttlefish showing courtship colouration
taken in Oman by David Collins

In addition to avoiding predators, pattern control is also used in courtship by male cuttlefish. This impresses females and warns off competitors. After mating the male will often defend the female while she lays clumps of eggs. These hatch in two to three months to reveal minature cuttlefish. Females only breed once and die soon after laying.

Eye of the cuttlefish, by Tim Nicholson

With its flattened body skirted each side with fins, the cuttlefish moves with a pretty rippling motion. Like the closely related octopus, it can also escape by powerful jet propulsion whilst simultaneously ejecting a cloud of black ink to distract its foe. This ink is called sepia and was once used by artists.

The cuttlefish's beak-like mouth is surrounded by eight arms each with two rows of suckers. It also has two long extendable tentacles with suckered, club-like ends for catching fast-moving prey like crustaceans and fish.

In this photo the cuttlefish is raising its tentacles in an aggressive posture, by Captain Victor Oram

To change colour, the cuttlefish has a central sac (chromatophore) containing granules of pigment. This is surrounded by a series of muscles. When the brain sends a signal to the cell, the contracting muscles make the central sacs expand, dispersing pigment and generating the optical effect. Their skin can change colour and pattern in just a second to match their environment. Scientists have recently also discovered that cuttlefish possess luminescent protein structures that allow them to actively emit light, not just reflect and filter the ambient light from their environment. Additionally, they also discovered the presence of reflectin in the chromatophores, a high-refractive-index protein that, they suggest, allows the chromatophores, when highly stretched out, to more effectively absorb light than if they contained color pigments alone.

According to Helmut Debelius, the hooded cuttlefish can grow to 30 cm but is usually only half that size.You find these cuttlefish in the Red Sea, Arabian Sea and Indian Ocean.

Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Coleoidea (Subclass) > Decapodiformes (Superorder) > Sepiida (Order)

Other Cuttlefish Photos: More cuttlefish photos are one our Cuttlefish page at http://www.scubatravel.co.uk/marine-life/cuttlefish.html

Further Reading:
Cuttlefish – Master of Camouflage by Scubabacus
Red Sea Reef Guide by Helmut Debelius

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