SCUBA Travel

The Cuttlefish - a Source of Inspiration

Cuttlefish, Sepia sp, taken on Agincourt Reef, Australia

Sepia sp.Cuttlefish
Taken off Agincourt Reef, Australia, by Tim Nicholson.

24 April 2014
The cuttlefish is a fascinating creature. 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". Cuttlefish could also help scientists create paper-thin flexible or wearable displays.

Hooded Cuttlefish, Sepia prashadi showing courtship colouration, taken in Oman
Hooded Cuttlefish showing courtship colouration, Sepia prashadi, 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, taken in Madeira

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.

Cuttlefish

The cuttlefish's mouth is surrounded by eight arms. It also has two long extendable tentacles and is thus classified as a decapod (10 feet). Carnivorous, cuttlefish catch fast-moving prey like crustaceans and fish with their long tentacles. They are found all over the world.

Cuttlefish has 8 arms and 2 tentacles
In this photo the cuttlefish is raising its tentacles in an aggressive posture

To change colour, the cuttlefish has a central sac (chromatophore) containing granules of pigment that 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.

The Cuttlefish bone is filled with small chambers. They fill or release air from these chambers to control their buoyancy.

You find the Hooded Cuttlefish in the Red Sea, Arabian Sea and Indian Ocean.

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

Photo copyright Tim Nicholson, David Collins, Captain Victor Organ.

By Jill Studholme

Further Reading
Cuttlefish: Master of Camouflage, by Scubabacus writing in SCUBA News
"Chameleon of the sea" reveals its secrets, Harvard School of Engineering and Applied Sciences
Great British Marine Animals, by Paul Naylor, Paperback, 235 pages (2003)
Leila F. Deravi, Andrew P. Magyar, et al The structure–function relationships of a natural nanoscale photonic device in cuttlefish chromatophores J R Soc Interface 2014 11: 20130942