Cuttlefish
From Simple English Wikipedia, the free encyclopedia
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 Two cuttlefish interact while a third looks on. Georgia Aquarium
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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.
Cuttlefish have an internal shell (cuttlebone), large eyes, 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 sharks, fish, and other cuttlefish. They live about 1 to 2 years.
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[edit] Anatomy
[edit] Cuttlebone
Cuttlefish have an internal structure called the cuttlebone. This is composed of calcium carbonate. It is porous, to provide the cuttlefish with buoyancy. Buoyancy can be regulated — the cuttlefish can even decide to sink — 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 "bone". Cuttlebones are traditionally used by jewellers 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. The cuttlebone is unique to cuttlefish, one of the features contrasting them with their squid relatives.
[edit] Changing color
Cuttlefish are sometimes called the chameleon of the sea because of their remarkable ability to rapidly change their skin colour 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.There are 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 would be produced by red and yellow chromatophores, while purple could be created by a red chromatophore and an iridophore. The cuttlefish could 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 whom can also sense polarization.
[edit] Eyes
Cuttlefish eyes are among the most developed in the animal kingdom. The organogenesis of cephalopod eyes is fundamentally different from that of vertebrates like humans.[1] Superficial similarities between cephalopod and vertebrate eyes are 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 essentially 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 instead pulled around by reshaping the entire eye in order to change focus.
[edit] 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 haemoglobin that is found in mammals. The blood is pumped by three separate hearts. Two of these 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 haemoglobin.
[edit] 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 Jews using the ink for the techelet dye on their Tallit strings.
[edit] Cuttlefish as food
Cuttlefish are caught for food in Mediterranean, and East Asian cultures. Although squid is more popular as a restaurant dish all over the world, in East Asia dried cuttlefish is a highly popular convenience snack food.
Cuttlefish is especially popular in Italy used in Risotto Nero and in the Croatian Crni Rižot, practically the same recipe, originated most probably from Venice, 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, greatly appreciates cuttlefish and squid ink for cooking due to the marine flavor and smoothness that it provides to the meals and it is included in dishes such as rice, pasta and fish stews.
[edit] Cuttlefish in literature
Cuttlefish made their most important literary appearance in the title of Eugenio Montale's ground-breaking debut collection of poetry entitled Cuttlefish Bones (Ossi di seppia), 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 science-fiction novel Frek and the Elixir, by Rudy Rucker, an alien named Professor Bumby presents himself to protagonist Frek in the form of a cuttlefish.
[edit] 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.
- CLASS CEPHALOPODA
- Subclass Nautiloidea: nautilus
- Subclass Coleoidea: squid, octopus, cuttlefish
- Superorder Octopodiformes
- Superorder Decapodiformes
- ?Order †Boletzkyida
- Order Spirulida: Ram's Horn Squid
- Order Sepiida: cuttlefish
- Suborder †Vasseuriina
- Family †Vasseuriidae
- Family †Belosepiellidae
- Suborder Sepiina
- Family †Belosaepiidae
- Family Sepiadariidae
- Family Sepiidae
- Suborder †Vasseuriina
- Order Sepiolida: bobtail squid
- Order Teuthida: squid
[edit] External links
- Scientific Database with photos and videos of cuttlefish and other cephalopods
- TONMO.com offers articles and forum discussion on cuttlefish care
- YouTube video of a cuttlefish harassing a diver
- YouTube video of cuttlefish hovering about. You can see colour changes and movement.
- Amazing cuttlefish - Cephalopods with natural camouflage and sepia ink
- Diving with cuttlefish
