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Top and bottom view of a cuttlebone, the buoyancy organ and internal shell of a cuttlefish
Cuttlebone of Sepia officinalis (left to right: ventral, dorsal, and lateral views)
Common cuttlefish Sepia officinalis
Tortoise with cuttlebone
Fossil cuttlebone of the Pliocene species Sepia rugulosa
Fossilised cuttlebone-like gladius of Trachyteuthis[1]

Cuttlebone, also known as cuttlefish bone, is a hard, brittle internal structure (an internal shell) found in all members of the family Sepiidae, commonly known as cuttlefish, a family within the cephalopods.

Cuttlebone is composed primarily of aragonite. It is a chambered, gas-filled shell used for buoyancy control; its siphuncle is highly modified and is on the ventral side of the shell.[2] The microscopic structure of cuttlebone consists of narrow layers connected by numerous upright pillars.

Depending on the species, cuttlebones implode at a depth of 200 to 600 metres (660 to 1,970 ft). Because of this limitation, most species of cuttlefish live on the seafloor in shallow water, usually on the continental shelf.[3]

Human uses[edit]

In the past, cuttlebones were ground up to make polishing powder. The powder was added to toothpaste, and was also used as an antacid or as an absorbent.

Today, cuttlebones are commonly used as calcium-rich dietary supplements for caged birds, chinchillas, hermit crabs, reptiles, and snails. It is not for human consumption. [4]

Jewelry making[edit]

Because cuttlebone is able to withstand high temperatures and is easily carved, it serves as mold-making material for small metal casting for the creation of jewelry and small sculptural objects.

Jewelers prepare cuttlebone for use as a mold by cutting it in half and rubbing the two sides together until they fit flush against one another. Then the casting can be done by carving a design into the cuttlebone, adding the necessary sprue, melting the metal in a separate pouring crucible, and pouring the molten metal into the mold through the sprue. Finally, the sprue is sawed off and the finished piece is polished.[5]

Internal structure[edit]

3D visualisation of a Sepia cuttlebone by industrial micro-computed tomography
Flight through the corresponding tomographic image stacks

See also[edit]


  1. ^ Fuchs, D., T. Engeser & H. Keupp (2007). Gladius shape variation in coleoid cephalopod Trachyteuthis from the Upper Jurassic Nusplingen and Solnhofen Plattenkalks. PDF Acta Palaeontologica Polonica 52(3): 575–589.
  2. ^ Rexfort, A.; Mutterlose, J. (2006). "Stable isotope records from Sepia officinalis—a key to understanding the ecology of belemnites?". Earth and Planetary Science Letters 247 (3–4): 212–212. Bibcode:2006E&PSL.247..212R. doi:10.1016/j.epsl.2006.04.025. 
  3. ^ Norman, M.D. 2000. Cephalopods: A World Guide. ConchBooks.
  4. ^ Norman, M.D. & A. Reid 2000. A Guide to Squid, Cuttlefish and Octopuses of Australasia. CSIRO Publishing.
  5. ^ Casting Silver with Cuttlefish