AskDefine | Define cuttlefish

Dictionary Definition

cuttlefish n : ten-armed oval-bodied cephalopod with narrow fins as long as the body and a large calcareous internal shell [syn: cuttle] [also: cuttlefishes (pl)]

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English

Noun

  1. Any of various squidlike cephalopod marine mollusks of the genus Sepia that have ten arms and a calcareous internal shell and eject a dark inky fluid when in danger

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Extensive Definition

Cuttlefish are marine animals of the order Sepiida belonging to the Cephalopoda class (which also includes squid, octopuses, and nautiluses). Despite their common name, cuttlefish are not fish but molluscs. Recent studies indicate that cuttlefish are among the most intelligent invertebrate species.
Cuttlefish have an internal shell (cuttlebone), large W-shaped pupils, and eight arms and two tentacles furnished with denticulated suckers, with which they secure their prey.
Cuttlefish eat small molluscs, crabs, shrimp, fish and other cuttlefish. Their predators include dolphins, sharks, fish, seals and other cuttlefish. Their life expectancy is about one to two years.

Anatomy

Cuttlebone

Cuttlefish possess an internal structure called the cuttlebone, which is porous and composed of calcium carbonate, to provide the cuttlefish with buoyancy. Buoyancy can be regulated by changing the gas-to-liquid ratio in the chambered cuttlebone. Each species has a distinct shape, size, and pattern of ridges or texture on the cuttlebone. The cuttlebone is unique to cuttlefish, one of the features contrasting them with their squid relatives. Cuttlebones are traditionally used by jewelers and silversmiths as moulds for casting small objects. They are probably better known today as the tough material given to parakeets and other cage birds as a source of dietary calcium.

Changing color

Cuttlefish are sometimes called the chameleon of the sea because of their remarkable ability to rapidly alter their skin color at will. Their skin flashes a fast-changing pattern as communication to other cuttlefish and to camouflage them from predators. This color-changing function is produced by groups of red, yellow, brown, and black pigmented chromatophores above a layer of reflective iridophores and leucophores, with up to 200 of these specialized pigment cells per square millimeter. The pigmented chromatophores have a sac of pigment and a large membrane that is folded when retracted. There are 6-20 small muscle cells on the sides which can contract to squash the elastic sac into a disc against the skin. Yellow chromatophores (xanthophores) are closest to the surface of the skin, red and orange are below (erythrophores), and brown or black are just above the iridophore layer (melanophores). The iridophores reflect blue and green light. Iridophores are plates of chitin or protein, which can reflect the environment around a cuttlefish. They are responsible for the metallic blues, greens, golds, and silvers often seen on cuttlefish. All of these cells can be used in combinations. For example, orange is produced by red and yellow chromatophores, while purple can be created by a red chromatophore and an iridophore. The cuttlefish can also use an iridophore and a yellow chromatophore to produce a brighter green. As well as being able to influence the color of the light that reflects off their skin, cuttlefish can also affect the light's polarization, which can be used to signal to other marine animals, many of which can also sense polarization.

Eyes

Cuttlefish eyes are among the most developed in the animal kingdom. The organogenesis of cephalopod eyes differs fundamentally from that of vertebrates like humans. Superficial similarities between cephalopod and vertebrate eyes are thought to be examples of convergent evolution. The cuttlefish pupil is a smoothly-curving W shape. Although they cannot see color, they can perceive the polarization of light, which enhances their perception of contrast. They have two spots of concentrated sensor cells on their retina (known as fovea), one to look more forward, and one to look more backwards. The lenses, instead of being reshaped as they are in humans, are pulled around by reshaping the entire eye in order to change focus.
Scientists have speculated that cuttlefish's eyes are fully developed before birth and start observing their surroundings, while in the egg. One team of French researches has additionally suggested that cuttlefish prefer to hunt the prey they saw before hatching.

Blood

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. The blood is pumped by three separate hearts, two of which are used for pumping blood to the cuttlefish's pair of gills (one heart for each gill), and the third for pumping blood around the rest of the body. 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.

Toxicity

Recently it has been discovered that the Pfeffer's Flamboyant Cuttlefish's muscles contain a highly toxic compound that is yet to be identified.

Ink

Cuttlefish have ink, like squid and octopuses. This ink was formerly an important dye, called sepia. Today artificial dyes have replaced natural sepia. However, there is a modern resurgence of Jewish people using the ink for the techelet dye on their Tallit strings.

As food

Cuttlefish are caught for food in the Mediterranean, East Asia, the English Channel and elsewhere. Although squid is more popular as a restaurant dish all over the world, in East Asia dried shredded cuttlefish is a highly popular snack food.
Cuttlefish is especially popular in Italy, where it is used in Risotto al Nero di Seppia (literally black cuttlefish rice). The Croatian Crni Rižot is virtually the same recipe, which probably originated in Venice and then spread across both coasts of the Adriatic. "Nero" and "Crni" mean black, the color the rice turns because of the cuttlefish ink. 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.

In literature

Eugenio Montale's ground-breaking debut collection of poetry Cuttlefish Bones (Ossi di seppia) was published in Turin in 1925. Montale, who grew up in Liguria along the Mediterranean Sea, was awarded the Nobel Prize for Literature in 1975, for his long and prolific career. Cuttlefish Bones remains one of the best-known and influential collections of 20th-century poetry.
In the popular novel Twenty Thousand Leagues Under the Sea by Jules Verne, Captain Nemo and his companions engage in a fierce battle with a group of giant cuttlefish. Although the creatures are defeated, one of the crew members is killed during the fight. Although Jules Verne accurately describes the cuttlefish's three hearts, he describes their blood as being red, instead of its actual greenish tint.
A 1923 drama by Stanisław Ignacy Witkiewicz is titled The Cuttlefish.
In his story The Call of Cthulhu, author H.P. Lovecraft likens the evil alien god's head to that of a cuttlefish.
In Rudy Rucker's 2007 novel Postsingular cuttlefish have mythical significance to people in a parallel universe (where they have already been fished to extinction). These "hibrane people" travel to our world to catch them, or steal them from fisherman's catches, causing them to mysteriously disappear.

Classification

There are over 120 species of cuttlefish currently recognised, grouped into 5 genera. Sepiadariidae contains seven species and 2 genera; all the rest are in Sepiidae.
cuttlefish in Min Nan: Hoe-ki
cuttlefish in Catalan: Sèpia
cuttlefish in Czech: Sépie
cuttlefish in German: Sepien
cuttlefish in Spanish: Sepiida
cuttlefish in French: Sepiida
cuttlefish in Korean: 갑오징어목
cuttlefish in Croatian: Sipa
cuttlefish in Hebrew: דיונונים
cuttlefish in Indonesian: Sotong
cuttlefish in Dutch: Zeekatten (inktvissen)
cuttlefish in Japanese: イカ#.E3.82.B3.E3.82.A6.E3.82.A4.E3.82.AB.E7.9B.AE_Sepiida
cuttlefish in Polish: Mątwy
cuttlefish in Portuguese: Choco
cuttlefish in Russian: Каракатица
cuttlefish in Slovenian: Sipe
cuttlefish in Sundanese: Balakutak
cuttlefish in Contenese: 墨魚
cuttlefish in Chinese: 乌贼
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