Squid ink pasta with truffles and pistachios It can also contain, among others, tyrosinase, dopamine, and L-DOPA, as well as small amounts of free amino acids, including taurine, aspartic acid, glutamic acid, alanine, and lysine. However, its main constituents are melanin and mucus. Chemical composition Ĭephalopod ink contains a number of chemicals in a variety of different concentrations, depending on the species. The light comes from a substance produced by a dedicated organ before being transferred into the ink sac. Heteroteuthis dispar is a cephalopod species known for releasing luminous ink. The particles have a density of 1.27 g cm −3, which may be due to the amount of metals that the ink has in its composition (4.7% in weight). Sepia officinalis ink forms a polydisperse suspension composed by spheric particles with a size between 80 and 150 nm (measured by TRPS and SEM). This section needs expansion with: examples of other inks besides that of the common cuttlefish, and comparisons between them. Cephalopod ink is nonetheless generally thought to be more sophisticated than a simple "smoke screen" the ink of a number of squid and cuttlefish has been shown to function as a conspecific chemical alarm. Few controlled experiments have been conducted to substantiate this. Many cephalopod predators (for instance moray eels) have advanced chemosensory systems, and some anecdotal evidence suggests that compounds (such as tyrosinase) found in cephalopod ink can irritate, numb or even deactivate such apparatus. Inking has been shown to protect species of squids against predatory fish attacks, as well during the capture phase as during the consummatory phase, due to visual and chemical effects of the ink releases. Numerous cuttlefish species add a coat of ink to their eggs, presumably to camouflage them from potential predators. Octopuses have also been observed squirting ink at snails or crabs approaching their eggs. The spotty bobtail squid releases ropes of ink longer than itself and hides among them, maybe to be confused with floating seagrass leaves. įurthermore, green turtle ( Chelonia mydas) hatchlings that have been observed mistakenly attacking pseudomorphs released by Octopus bocki have subsequently ignored conspecific octopuses. Thus, such capture avoidance method is analogous to fighter jet dogfights where the followed pilot releases countermeasures (such as flares) to misdirect the sensors in some guided missiles. The pseudomorphs are roughly the same volume as and look similar to the cephalopod that released them, and many predators have been observed attacking them mistakenly, allowing the cephalopod to escape (this behaviour is often referred to as the "blanch-ink-jet manoeuvre"). These are expelled slightly away from the cephalopod in question, which will often release several pseudomorphs and change colour ( blanch) in conjunction with these releases. The second response to a predator is to release pseudomorphs ("false bodies"), smaller clouds of ink with a greater mucus content, which allows them to hold their shape for longer. The first is the release of large amounts of ink into the water by the cephalopod in order to create a dark, diffuse cloud (much like a smoke screen) that can obscure the predator's view, allowing the cephalopod to make a rapid retreat by jetting away. Two distinct behaviors have been observed in inking cephalopods. they darted tail first, with the rapidity of an arrow, from one side of the pool to the other, at the same instant discolouring the water with a dark chestnut-brown ink.Ĭharles Darwin, The Voyage of the Beagle Escape strategies ![]() I was much interested, on several occasions, by watching the habits of an Octopus or cuttle-fish. The shapes taken by ink releases are classified as six types: Each species of cephalopod produces slightly differently coloured inks generally, octopuses produce black ink, squid ink is blue-black, and cuttlefish ink is a shade of brown.Ī number of other aquatic molluscs have similar responses to attack, including the gastropod clade known as sea hares. Its dark colour is caused by its main constituent, melanin. The ink is released from the ink sacs (located between the gills) and is dispersed more widely when its release is accompanied by a jet of water from the siphon. ![]() ![]() All cephalopods, with the exception of the Nautilidae and the Cirrina (deep-sea octopuses), are able to release ink to confuse predators. Ventral view of the viscera of Chtenopteryx sicula, showing the location of the ink sacĬephalopod ink is a dark-coloured or luminous ink released into water by most species of cephalopod, usually as an escape mechanism.
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