Cuttlefish possess an internal structure called the cuttlebone (or cuttlefish bone).
A cuttlefish's heart must pump a higher blood flow than most other animals because hemocyanin is substantially less capable of carrying oxygen than hemoglobin.
Scientists have speculated that cuttlefish's eyes are fully developed before birth and start observing their surroundings while still in the egg.
Cuttlefish belong to the subclass Coleoidea, along with octopuses, squids, and the extinct belemites.
The blood of a cuttlefish is an unusual shade of green-blue because it uses the copper-containing protein hemocyanin to carry oxygen instead of the red iron-containing protein hemoglobin that is found in mammals.
Cuttlefish are popular as a food in various countries, and particularly in Japan, India, and many Mediterranean countries (Herbst 2001).
Iridophores are plates of chitin or protein, which can reflect the environment around a cuttlefish.
Cuttlefish can move short distances in any direction by rippling of a flap of muscle around the mantle.
Spanish cuisine, especially that of the coastal regions, uses cuttlefish and squid ink for the marine flavor and smoothness it provides; it is included in dishes such as rice, pasta, and fish stews.
Cuttlefish have a remarkable ability to rapidly alter their skin color at will.
Each species of cuttlefish has a distinct shape, size, and pattern of ridges or texture on the cuttlebone.
Their skin flashes a fast-changing pattern as communication to other cuttlefish and to camouflage from predators.
The cuttlebone of cuttlefish offer addition values, including use as a source of calcium for caged birds and use as molds by jewelers and silversmiths for casting small objects.
Cuttlefish is especially popular in Italy, where it is used in Risotto al Nero di Seppia (literally black cuttlefish rice).
Recent studies indicate that the cuttlefish and octopus are among the most intelligent invertebrate species.
Despite their common name, cuttlefish are not fish but members of the invertebrate phylum Mollusca.
Cuttlefish differ from squid in that cuttlefish have an internal shell (cuttlebone) on their back.
Some taxonomies list the cuttlefish as part of the order Sepioidea, which is made up of five families, including Sepiadariidae and Sepiidae, as well as Sepiolida (bobtail squid), Spirulidae, and Idiosepiidae.
Ecologically, the carnivorous cuttlefish are important in marine food chains, preying upon small mollukcs, crabs, shrimp, fish, and other cuttlefish, while being preyed upon by dolphins, sharks, fish, seals, and other cuttlefish.
The cuttlebone provides the cuttlefish with buoyancy control, with buoyancy regulated by changing the gas-to-liquid ratio in the chambered cuttlebone.
The cuttlebone, which is a chambered and gas-filled shell, is unique to cuttlefish and one of the features contrasting them with their squid relatives.
Among the extant Coleoidea, cuttlefish are distinguished from the octopuses by the cuttlefish having eight arms and two tentacles, while octopuses have eight arms and no tentacles.
Cuttlefish are members of the Mollusca phylum, a taxon that includes such familiar animals as snails, clams, oysters, mussels, nudibranchs, abalones, and octopuses.
The cuttlefish can also use an iridophore and a yellow chromatophore to produce a brighter green.