Cuttlefish are photochromic, and are sometimes referred to as 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.
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 still in the egg. One team of French researchers has additionally suggested that cuttlefish prefer to hunt the prey they saw before hatching.
Recently it has been discovered that the Pfeffer's Flamboyant Cuttlefish's muscles contain a highly toxic compound that is yet to be identified. Research by Mark Norman with the Museum Victoria in Queensland, Australia, has shown the toxin to be as lethal as that of a fellow cephalopod, the Blue-ringed octopus.
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 Ireland a popular dish called "Cuttle Chips" consists of deep fried cuttlefish covered in a cajun mayonnaise and shredded cheddar. Piled on top of the cheese are ground beef, tomato, peppers, onions, and various seasonings.
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 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.
In the Poetry Collection 'Dragons' by Matthew Francis, there is a poem titled 'What the Cuttlefish Do', which makes various references to Cuttlefish, including their ability to change colour and mating habits.