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Cephalopod ink is a dark-coloured or luminous ink released into water by most species of cephalopod, usually as an escape mechanism. All cephalopods, with the exception of the Nautilidae and the Cirrina (deep-sea octopuses), [ 1 ] are able to release ink to confuse predators .
An ink sac is an anatomical feature that is found in many cephalopod mollusks used to produce the defensive cephalopod ink. With the exception of nocturnal and very deep water cephalopods , all Coleoidea (squid, octopus and cuttlefish) which dwell in light conditions have an ink sac, which can be used to expel a cloud of dark ink in order to ...
Fishers sometimes call cephalopods "inkfish", referring to their common ability to squirt ink. The study of cephalopods is a branch of malacology known as teuthology . Cephalopods became dominant during the Ordovician period, represented by primitive nautiloids .
According to the Pigment Compendium, [2] atramentum is a historical pigment or ink based on carbon black. The painter Apelles has been credited for making atramentum elephantinum by burning ivory , and Pliny the Elder in his Natural History comments on Apelles' skilled use of black varnish.
They may have avoided predation by squirting ink, much like modern cephalopods; ink is occasionally preserved in fossil specimens. [34] Many ammonite shells have been found with round holes once interpreted as a result of limpets attaching themselves to the shells.
Melanin produced by plants are sometimes referred to as 'catechol melanins' as they can yield catechol on alkali fusion. It is commonly seen in the enzymatic browning of fruits such as bananas. Chestnut shell melanin can be used as an antioxidant and coloring agent. [ 49 ]
Coleoid cephalopods (including octopuses, squids and cuttlefish) have complex multicellular organs that they use to change colour rapidly, producing a wide variety of bright colours and patterns. Each chromatophore unit is composed of a single chromatophore cell and numerous muscle, nerve, glial , and sheath cells. [ 43 ]
Both the opaline and ink gland secrete different substances that when mixed together form the ink released during phagomimicry. The secretion is very acidic (ink having a pH of 4.9 and opaline having a pH of 5.8) and contains high levels of bioactive molecules that can serve as feeding stimulants, feeding deterrents, and aversive compounds.