What does cuttlebone mean?
A cuttlebone is the internal shell of a cuttlefish, a squid-like marine mollusc. Unlike an external seashell, this structure sits inside the animal's body and consists of a lightweight, highly porous plate of aragonite, which the cuttlefish uses to regulate its buoyancy by varying the gas and fluid within it. Because these shells are buoyant yet brittle, they frequently wash up on beaches after the animal has died, appearing as smooth, chalky-white ovals. The most familiar everyday use of the word arises in bird keeping: cuttlebones are widely sold as supplements for caged birds such as budgerigars, canaries, and parrots, which rasp against them both to obtain calcium and to keep their continuously growing beaks trimmed. The word is purely literal and functional, with no figurative extensions, and it appears chiefly in contexts involving pets, natural history, and shoreline finds.
nounThe internal, porous calcified shell of a cuttlefish, often washed up on beaches or sold as a calcium supplement and beak-conditioning aid for caged birds.
- The internal calcified shell of a cuttlefish, used as a dietary calcium source and beak conditioner for pet birds.
"The budgerigar spent all morning nibbling at the cuttlebone clipped inside its cage."
"She clipped a fresh cuttlebone to the side of the parakeet's cage each month."
"Worn cuttlebones sometimes wash ashore after storms, their chalky white shells scattered among the seaweed."
Regular plural; commonly used when discussing stock for aviaries or collections of beach-found shells.
"The pet shop sold cuttlebones in packs of six."
Despite the name, a cuttlebone is not a bone at all — it's the gas-filled internal shell that lets a cuttlefish control its buoyancy.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cuttlebone
The word combines 'cuttle', from the Old English 'cudele' meaning cuttlefish, with 'bone', reflecting the long-standing folk description of this structure even though it is technically a shell rather than a bone. The compound has been in English use for centuries alongside the alternative form 'cuttlefish bone'. The element 'cuttle' survives in modern English chiefly through 'cuttlefish' and 'cuttlebone' themselves.
How cuttlebone is actually used
A plain, practical word found mainly in contexts of bird-keeping, beachcombing, and marine biology. It carries no figurative or emotional connotations. The older form 'cuttlefish bone' is common in British usage, especially in traditional avian care and craft references.
Easily confused with cuttlebone
A cuttlefish is the living marine mollusc, while a cuttlebone is only its internal calcified shell.