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Cephalopod ink is a dark pigment released into water by most species of cephalopod
Cephalopod

The cephalopods are the mollusc class Cephalopoda characterized by bilateral symmetry, a prominent head, and a modification of the mollusk foot, a muscular hydrostat, into the form of cephalopod arms or tentacles....
, usually as an escape mechanism. All cephalopods, with the exception of the Nautilidae and the species of octopus
Octopus

The octopus is a cephalopod of the order Octopoda that inhabits many diverse regions of the ocean, especially coral reefs. The term may also refer to only those creatures in the genus Octopus ....
 belonging to the suborder
Order

Order may refer to:...
 Cirrina, are able to release ink.

The ink is released from the ink sac
Ink sac

With the exception of nocturnal and very deep water cephalopods, all coeloids which dwell in light conditions have an ink sac, which can be used to expel a cloud of dark cephalopod ink to confuse predators....
s (located between the gill
Gill

A gill is an anatomical structure found in many aquatic ecosystem organisms. It is a respiration organ whose function is the extraction of oxygen from water and the excretion of carbon dioxide....
s) and is dispersed more widely by accompanying its release with a jet of water from the funnel.






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Cephalopod ink is a dark pigment released into water by most species of cephalopod
Cephalopod

The cephalopods are the mollusc class Cephalopoda characterized by bilateral symmetry, a prominent head, and a modification of the mollusk foot, a muscular hydrostat, into the form of cephalopod arms or tentacles....
, usually as an escape mechanism. All cephalopods, with the exception of the Nautilidae and the species of octopus
Octopus

The octopus is a cephalopod of the order Octopoda that inhabits many diverse regions of the ocean, especially coral reefs. The term may also refer to only those creatures in the genus Octopus ....
 belonging to the suborder
Order

Order may refer to:...
 Cirrina, are able to release ink.

The ink is released from the ink sac
Ink sac

With the exception of nocturnal and very deep water cephalopods, all coeloids which dwell in light conditions have an ink sac, which can be used to expel a cloud of dark cephalopod ink to confuse predators....
s (located between the gill
Gill

A gill is an anatomical structure found in many aquatic ecosystem organisms. It is a respiration organ whose function is the extraction of oxygen from water and the excretion of carbon dioxide....
s) and is dispersed more widely by accompanying its release with a jet of water from the funnel. Its dark color is caused by its main constituent, melanin
Melanin

Melanin is a class of compounds found in the plant, animal, and protista kingdom , where it serves predominantly as a pigment. The class of pigments are derivatives of the amino acid tyrosine....
. Each species of cephalopod produces slightly differently coloured inks; generally, octopuses produce black ink, squid ink is blue-black and cuttlefish ink is brown (see Use by humans
Cephalopod ink

Cephalopod ink is a dark pigment released into water by most species of cephalopod, usually as an escape mechanism. All cephalopods, with the exception of the Nautilidae and the species of octopus belonging to the Order Cirrina, are able to release ink....
).

A number of other aquatic molluscs have evolved similar responses to attack, including sea hare
Sea hare

The suborder Aplysiomorpha or Sea hares are very large sea slugs with a soft internal shell made of protein. These are marine gastropod molluscs in the superfamilies Aplysioidea and Akeroidea....
s. This is an example of convergent evolution
Convergent evolution

Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action....
.

Inking behaviours


Two distinct behaviours have been observed in inking cephalopods. 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 smokescreen) which can obscure the predator’s view, allowing the cephalopod in question to make a rapid retreat by jetting away.
The second response to a predator is to release ‘pseudomorphs’ (‘false bodies’); smaller clouds of ink with a greater mucus
Mucus

In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. It is a viscous colloid containing antiseptic enzymes and immunoglobulins that serves to protect Epithelium in the respiratory,...
 content, which allows them to hold their shape for longer. These are expelled slightly away from the cephalopod in question, which will often release several pseudomorphs and change color (blanch) in conjunction with these releases. The pseudomorphs are roughly the same volume and look similar to the cephalopod that released them, and many predators have been observed attacking them mistakenly, allowing the cephalopod to escape (this behavior is often referred to as the ‘Blanch-Ink-Jet Maneuver’). Furthermore, green turtle hatchlings (Chelonia mydas) that have been observed mistakenly attacking pseudomorphs released by Octopus bocki have subsequently ignored conspecific
Conspecificity

Conspecificity is a concept in biology. Two or more individual organisms, populations, or taxa are termed conspecific if they belong to the same species....
 octopuses. However, many cephalopod predators (for instance moray eel
Moray eel

Moray eels are large cosmopolitan eels of the family Muraenidae. There are approximately 200 species in 15 genera. The typical length of a moray is 1.5 m , with the largest being the slender giant moray, Strophidon sathete, at up to 4 m ....
s) have advanced chemosensory
Chemosensor

A chemosensor, also known as chemoreceptor, is a sensory receptor that transduction a chemical signal into an action potential. Or, more generally, a chemosensor detects certain chemical stimuli in the environment....
 systems, and some anecdotal evidence suggests that compounds such as tyrosinase
Tyrosinase

Tyrosinase is an enzyme that Catalysis the oxidation of phenols and is widespread in plants and animals. Tyrosinase is a copper-containing enzyme present in plant and animal tissues that catalyzes the production of melanin and other pigments from tyrosine by oxidation, as in the blackening of a peeled or sliced potato exposed to air....
 found in cephalopod ink can irritate, numb or even deactivate such apparatus. Unfortunately, few controlled experiments have been conducted to substantiate this. Cephalopod ink is nonetheless generally thought to be more sophisticated than a simple ‘smokescreen;’ the ink of a number of squid and cuttlefish has been shown to function as a conspecific chemical alarm.
Octopuses have also been observed squirting ink at snail
Gastropoda

The class Gastropoda or gastropods are members of the phylum Mollusca and are more commonly known as "snails and slugs".This is the most diversified class in the phylum, with to 80,000 living species....
s or crab
Crab

Crabs are Decapoda crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax....
s approaching their eggs
Egg (biology)

In most birds and reptiles, an egg is the zygote, resulting from fertilization of the ovum. To enable incubation the egg is usually kept within a favourable temperature range as it nourishes and protects the growing embryo....
.

Chemical composition

Cephalopod ink contains a number of chemicals in a variety of different concentrations, depending on the species. However, its main constituents are melanin
Melanin

Melanin is a class of compounds found in the plant, animal, and protista kingdom , where it serves predominantly as a pigment. The class of pigments are derivatives of the amino acid tyrosine....
 and mucus
Mucus

In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. It is a viscous colloid containing antiseptic enzymes and immunoglobulins that serves to protect Epithelium in the respiratory,...
. It can also contain, among other things, tyrosinase
Tyrosinase

Tyrosinase is an enzyme that Catalysis the oxidation of phenols and is widespread in plants and animals. Tyrosinase is a copper-containing enzyme present in plant and animal tissues that catalyzes the production of melanin and other pigments from tyrosine by oxidation, as in the blackening of a peeled or sliced potato exposed to air....
, dopamine
Dopamine

Dopamine is a neurotransmitter occurring in a wide variety of animals, including both vertebrates and invertebrates. In the human brain, this phenethylamine functions as a neurotransmitter, activating the five types of dopamine receptors ? D1, D2, D3, D4 and D5, and their variants....
 and L-DOPA, and small amounts of amino acid
Amino acid

In chemistry, an amino acid is a molecule containing both amine and carboxyl functional groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent....
s, including taurine
Taurine

Taurine, or 2-aminoethanesulfonic acid, is an organic acid. It is also a major constituent of bile and can be found in the lower intestine and in small amounts in the tissues of many animals and in humans as well....
, aspartic acid
Aspartic acid

Aspartic acid is an a-amino acid with the chemical formula HO2CCHCH2CO2H. The carboxylate anion of aspartic acid is known as aspartate....
, glutamic acid
Glutamic acid

Glutamic acid is one of the 20 proteinogenic amino acids and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salt of glutamic acid are known as glutamates....
, alanine
Alanine

Alanine is an a-amino acid with the chemical formula CH3CHCOOH. The L-isomer is one of the 20 proteinogenic amino acids, i.e. the building blocks of proteins....
 and lysine
Lysine

Lysine is an a-amino acid with the chemical formula HO2CCH4NH2. This amino acid is an essential amino acid, which means that humans cannot synthesize it....
.

Use by humans

Cephalopod ink has, as its name suggests, been used in the past as ink
Ink

An ink is a liquid containing various pigments and/or dyes used for coloring a surface to produce an , writing, or design. Ink is used for drawing and/or writing with a pen, brush or quill....
; indeed, the Greek
Ancient Greece

The term Ancient Greece refers to the period of History of Greece lasting from the Greek Dark Ages ca. 1100 BC and the Dorian invasion, to 146 BC and the Roman Republic conquest of Greece after the Battle of Corinth ....
 name for cuttlefish, and the taxonomic
Taxonomy

Taxonomy is the practice and science of classification. The word comes from the Greek language ', taxis and ', nomos .Taxonomies, or taxonomic schemes, are composed of taxonomic units known as taxa , or kinds of things that are arranged frequently in a hierarchical structure....
 name of a cuttlefish genus, Sepia
Sepia (genus)

Sepia is a genus of cuttlefish encompassing some of the best known and most common species. The name of the genus is the Latinized form of the Greek_language s?p?a, sep?a, cuttlefish....
, is associated with the brown colour of cuttlefish ink (for slightly more information, see Sepia (color)
Sepia (color)

Sepia is a dark brown-grey color, named after the rich brown pigment derived from the ink sac of the common cuttlefish Sepia .The word sepia is the Latinized form of the Greek_language s?p?a, sep?a, cuttlefish....
). Modern use of cephalopod ink is generally limited to cooking
Cooking

Cooking is the process of preparing food by applying heat, selecting, measuring and combining of ingredients in an ordered procedure for producing safe and edible food....
, where it is used as a food colouring, for example in pasta
Pasta

Pasta is a generic term for Italian cuisine variants of noodles, food made from a dough of flour, water and/or Egg , that is Boiling. The word can also denote dishes in which pasta products are the primary ingredient, served with sauce or seasonings....
 and sauces. For this purpose it is generally obtainable from fishmonger
Fishmonger

A fishmonger is someone who sells fish and seafood. In some countries modern supermarkets are replacing fishmongers who operate in shops or markets....
s. The ink is extracted from the ink sacs during preparation of the dead cephalopod, usually squid, and therefore contains no mucus. Recent studies have shown that cephalopod ink is toxic to some cell
Cell (biology)

The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life....
s, including tumor cells
Tumor

A tumor or tumour is the name for a swelling or lesion formed by an abnormal growth of cells . Tumor is not synonymous with cancer. A tumor can be Benign neoplasm, Carcinoma in situ or malignant, whereas cancer is by definition malignant....
.

See also

  • Cephalopod
    Cephalopod

    The cephalopods are the mollusc class Cephalopoda characterized by bilateral symmetry, a prominent head, and a modification of the mollusk foot, a muscular hydrostat, into the form of cephalopod arms or tentacles....
  • Octopus
    Octopus

    The octopus is a cephalopod of the order Octopoda that inhabits many diverse regions of the ocean, especially coral reefs. The term may also refer to only those creatures in the genus Octopus ....
  • Squid
    Squid

    Squid are marine cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, Symmetry #Bilateral_symmetry, a mantle , and cephalopod arms....
  • Cuttlefish
    Cuttlefish

    Cuttlefish are Marine animals of the order Sepiida belonging to the Cephalopoda class . Despite their common name, cuttlefish are not fish but molluscs....
  • Inkfish
    Inkfish

    Inkfish is a term applied to cephalopods, primarily in fisheries science and the fishing industry, paralleling the terms Whitefish , oily fish, and shellfish. The name refers to the ability of many cephalopods to squirt "ink" when alarmed....


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