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Cuttlefishes

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Cuttlefish images (order Sepiida) - stock photos & facts showing this animal that can change color in a flash

Scientific classification | Kingdom: Animalia > Phylum: Mollusca > Class: Cephalopoda > Superorder: Decapodiformes > Order: Sepiida

Cuttlefish are marine invertebrates closely related to octopus and squid, and are often called the chameleon of the sea for their incredible ability to camouflage themselves. Despite their name, they are not fish, and considered to be the most intelligent of the marine invertebrates. Cuttlefish are photochromic, and can rapidly alter their skin color at will to blend in with whatever their background is. They also use rapidly changing color patterns to signal and communicate with other cuttlefish. This color change 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 special cells per square millimeter. All of the cells can be used in combination to produce a wide range of colors, including metallics and iridescent colors.

The cuttlefish propels itself by spurts, drawing water into a compression chamber which it squeezes to jet the water out a funnel under the head. Cuttlefish have an internal shell, known as cuttlebone, that differentiates them from squid and octopus. The mantle houses the cuttlebone, reproductive organs and digestive organs. The head is at the base of the mantle with eyes on either side and a beak-like jaw in the center. Below the mantle are eight arms, and two prehensile, retractable tentacles covered in suckers with which to seize their prey.

Cuttlefish have three hearts, one for each gill, and one to pump blood around the rest of their body. Their blood is greenish blue and uses hemocyanin to carry oxygen instead of the hemoglobin used by red-blooded mammals. Another unusual feature is their eyes, which are among the most developed in the animal kingdom. The pupil is in a W shape, and they see polarization of light rather than color which give them a greater contrast. They change focus by reshaping the entire eye, instead of just the lens.

Cuttlefish feed on small mollusks, crustaceans, and fish. In turn they are preyed upon by dolphins, seals, sharks and other large predatory fish. Like their cousins the squid and octopus, cuttlefish have ink. This was used as a dye called sepia, but modern dyes have now replaced the need for cuttlefish ink. Cuttlefish use the ink to distract a predator, shooting the ink out into the water and swimming away to safety behind the cloud of ink.

Cuttlefish reproduce year round. Males transfer sperm to the female with an arm specially modified for mating. The eggs are stored in the oviduct of the females then deposited on the sea floor, covered in ink as camouflage. Young hatch with a yolk sac which they feed upon until they have learned to catch small shrimp. Their life expectancy is about two years.
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