8 Apr 2013

Cuttlefish bone.

Lurking among the low tide rocks, the remains of a cuttlefish that has shuffled off this mortal coil...
The wonderfully named cuttlebone is made of aragonite, the same material that makes up the hard shells of limpets, whelks and long-extinct ammonites. The cuttlebone is chambered and the cuttlefish changes the gas/water ratio to adjust its buoyancy and so alter their depth in the sea. Cuttlefish are reported to be smart molluscs: they have the largest brain to body ratio of the invertebrates, a highly developed sense of sight and the ability to camouflage themselves using chromatophores (pigment cells) in their skin. They live for up to two years, feeding on crabs and fish and when under threat themselves emit clouds of sepia camouflage 'ink' which, unfortunately, makes them attractive for chefs and gourmands who feel pasta is incomplete without some cuttlefish juice. Each species of cuttlefish (there are estimated to be 120) has a unique cuttlebone. Here's this splendid piece of evolution close up:

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