Cephalopod ink

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Ventral view of the viscera of Chtenopteryx sicula, showing the specific location of the ink sac Chtenopteryx sicula2.jpg
Ventral view of the viscera of Chtenopteryx sicula , showing the specific location of the ink sac

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. [2]

Contents

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. Its dark colour is caused by its main constituent, melanin. 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.

A number of other aquatic molluscs have similar responses to attack, including the gastropod clade known as sea hares.

Types of ink shapes

The shapes taken by ink releases are classified as six types: [3]

Inking behaviours

I was much interested, on several occasions, by watching the habits of an Octopus or cuttle-fish ... 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.

Charles Darwin, The Voyage of the Beagle

Escape strategies

Two distinct behaviors 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 smoke screen) that can obscure the predator's view, allowing the cephalopod 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 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 colour (blanch) in conjunction with these releases. 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").

Furthermore, green turtle (Chelonia mydas) hatchlings that have been observed mistakenly attacking pseudomorphs released by Octopus bocki have subsequently ignored conspecific octopuses. [4]

Hiding strategy

The spotty bobtail squid releases ropes of ink longer than itself and hides among them, possibly to be confused with floating seagrass leaves. [5]

Behavior around eggs

Octopuses have also been observed squirting ink at snails or crabs approaching their eggs. [6]

Numerous cuttlefish species add a coat of ink to their eggs, presumably to camouflage them from potential predators. [7]

Properties

Attack protection

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. [8]

Chemical effects

Many cephalopod predators (for instance moray eels) have advanced chemosensory systems, and some anecdotal evidence [9] suggests that compounds (such as tyrosinase) found in cephalopod ink can irritate, numb or even deactivate such apparatus. Few controlled experiments have been conducted to substantiate this. 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. [6] [10]

Physical properties

Sepia officinalis ink forms a polydisperse suspension composed by spheric particles with a size between 80 and 150 nm (measured by TRPS and SEM). 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). [11]

Heteroteuthis dispar is a cephalopod species known for releasing luminous ink. The light comes from a substance produced by a dedicated organ before being transferred into the ink sac. [12]

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 and mucus. [13] It can also contain, among others, tyrosinase, dopamine, and L-DOPA, [13] [14] as well as small amounts of free amino acids, including taurine, aspartic acid, glutamic acid, alanine, and lysine. [6]

Use by humans

Arros negre owes its dark colour to squid ink Arrosnegre.png
Arròs negre owes its dark colour to squid ink

Cephalopod ink has, as its name suggests, been used in the past as ink for pens and quills; the Greek name for cuttlefish, and the taxonomic name of a cuttlefish genus, Sepia , is associated with the brown colour of cuttlefish ink (for more information, see sepia).

Squid ink pasta with truffles and pistachios Black pasta with truffle and pistachio.jpg
Squid ink pasta with truffles and pistachios

Modern use of cephalopod ink is generally limited to cooking, primarily in Japan and the Mediterranean, where it is used as a food colouring and flavouring, for example in pasta and sauces, and calamares en su tinta . For this purpose, it is generally obtainable from fishmongers, gourmet food suppliers, and is widely available in markets in Japan, [15] (p 336) Italy and Spain. The ink is extracted from the ink sacs during preparation of the dead cephalopod, usually cuttlefish, and therefore contains no mucus. While it is not commonly used in China, cephalopod ink is sometimes used to dye the dough of dumplings.

Studies have shown that cephalopod ink is toxic to some cells, including tumor cells. [6] It is being researched in mice for its antitumor activity against Meth-A fibrosarcoma. It currently remains unclear however if any of the antitumor activity of squid ink can be obtained from oral consumption, and this is indicated as an area for future investigation. [15] (p 331)

Related Research Articles

<span class="mw-page-title-main">Squid</span> Superorder of cephalopod molluscs

A squid is a mollusc with an elongated soft body, large eyes, eight arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida. Like all other cephalopods, squid have a distinct head, bilateral symmetry, and a mantle. They are mainly soft-bodied, like octopuses, but have a small internal skeleton in the form of a rod-like gladius or pen, made of chitin.

<span class="mw-page-title-main">Cephalopod</span> Class of mollusks

A cephalopod is any member of the molluscan class Cephalopoda such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot. 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.

<span class="mw-page-title-main">Ink sac</span> Organ in cephalopods used to squirt ink in defense

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 which dwell in light conditions have an ink sac, which can be used to expel a cloud of dark ink in order to confuse predators.

<i>Euprymna tasmanica</i> Species of mollusc

Euprymna tasmanica, also known as the southern dumpling squid or southern bobtail squid, is a bobtail squid that lives in the shallow temperate coastal waters of southern Australia's continental shelf. It lives for between 5 and 8 months and the adults can grow up to 6 or 7 cm long with a mantle length of 3 to 4 cm. They are found in seagrass beds or areas with soft silty or muddy bottoms from Brisbane on the east coast to Shark Bay on the west, as well as around Tasmania. Southern dumpling squid are nocturnal and during the day hide in sand or mud covered in a mucus-lined coat of sediment. If disturbed acid glans can quickly remove this coat as an additional decoy to ink squirting.

<span class="mw-page-title-main">Caribbean reef squid</span> Species of squid

The Caribbean reef squid, commonly called the reef squid, is a species of small, torpedo-shaped squid with undulating fins that extend nearly the entire length of the body, approximately 20 cm in length. They are most commonly found in the Caribbean Sea in small schools. As part of the Cephalopod class of Molluscs, these organisms exhibit specific characteristics to help them in their environment, such as tentacles for movement and feeding and color pigments that reflect their behavioral conditions.

<span class="mw-page-title-main">Common cuttlefish</span> Species of cephalopod

The common cuttlefish or European common cuttlefish is one of the largest and best-known cuttlefish species. They are a migratory species that spend the summer and spring inshore for spawning and then move to depths of 100–200 metres (330–660 ft) during autumn and winter. They grow to 49 centimetres (19 in) in mantle length and 4 kilograms (8.8 lb) in weight. Animals from subtropical seas are smaller and rarely exceed 30 centimetres (12 in) in mantle length.

<span class="mw-page-title-main">Pharaoh cuttlefish</span> Species of cephalopods

The pharaoh cuttlefish is a large cuttlefish species, growing to 42 cm in mantle length and 5 kg in weight.

<i>Sepia dollfusi</i> Species of cuttlefish

Sepia dollfusi is a species of cuttlefish native to the Red Sea and southern part of the Suez Canal. The depth range of S. dollfusi is unknown. It has been recorded once in the Egyptian sector of the Mediterranean Sea, so it is potentially a Lessepsian migrant into the Mediterranean via the Suez Canal.

<i>Sepia mestus</i> Species of cuttlefish

Sepia mestus, also known as the reaper cuttlefish or red cuttlefish, is a species of cuttlefish native to the southwestern Pacific Ocean, specifically Escape Reef off Queensland to Murrays Beach off Jervis Bay. Reports of this species from China and Vietnam are now known to be misidentifications. S. mestus lives at a depth of between 0 and 22 m.

Sepia hedleyi, or Hedley's cuttlefish, is a species of cuttlefish in the family Sepiidae, endemic to subtropical and temperate waters off Australia.

<i>Euprymna scolopes</i> Species of cephalopods known as the Hawaiian bobtail squid

Euprymna scolopes, also known as the Hawaiian bobtail squid, is a species of bobtail squid in the family Sepiolidae native to the central Pacific Ocean, where it occurs in shallow coastal waters off the Hawaiian Islands and Midway Island. The type specimen was collected off the Hawaiian Islands and is located at the National Museum of Natural History in Washington, D.C.

Sepietta petersi, also known as the mysterious bobtail, is a species of bobtail squid native to the Mediterranean Sea. A doubtful record of S. petersi also exists from the Atlantic Ocean off Morocco.

<i>Idiosepius pygmaeus</i> Species of mollusc

Idiosepius pygmaeus, also known as the two-toned pygmy squid or tropical pygmy squid, is a species of bobtail squid native to the Indo-Pacific. It occurs in waters of the South China Sea, Japan, Philippines, Palau, Indonesia, Northern Mariana Islands, as well as northern and northeastern Australia. It inhabits shallow, inshore waters.

<span class="mw-page-title-main">Cuttlefish</span> Order of molluscs

Cuttlefish, or cuttles, are marine molluscs of the suborder Sepiina. They belong to the class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone, which is used for control of buoyancy.

<span class="mw-page-title-main">Bigfin reef squid</span> Species of squid


Sepioteuthis lessoniana, commonly known as the bigfin reef squid, tiger squid, glitter squid, oval squid, or northern calamari, is a species of loliginid squid. It is one of the three currently recognized species belonging to the genus Sepioteuthis. Studies in 1993, however, have indicated that bigfin reef squids may comprise a cryptic species complex. The species is likely to include several very similar and closely related species.

<span class="mw-page-title-main">Deimatic behaviour</span> Bluffing display of an animal used to startle or scare a predator

Deimatic behaviour or startle display means any pattern of bluffing behaviour in an animal that lacks strong defences, such as suddenly displaying conspicuous eyespots, to scare off or momentarily distract a predator, thus giving the prey animal an opportunity to escape. The term deimatic or dymantic originates from the Greek δειματόω (deimatóo), meaning "to frighten".

<span class="mw-page-title-main">Louise Allcock</span> British researcher

Louise Allcock is a British researcher, best known for her work on ecology and evolution of the cephalopods of the Southern Ocean and deep sea. She is the editor of the Zoological Journal of the Linnean Society.

<i>Sepioloidea lineolata</i> Species of cuttlefish

Sepioloidea lineolata or more commonly known as the striped pyjama squid or the striped dumpling squid is a type of bottletail squid that inhabits the Indo-Pacific Oceans of Australia. The striped pyjama squid lives on the seafloor and is both venomous and poisonous. When fully mature, a striped pyjama squid will only be about 7 to 8 centimetres in length. Baby striped pyjama squid can be smaller than 10 millimetres (0.39 in).

Octopus bocki is a species of octopus, which has been located near south Pacific islands such as Fiji, the Philippines, and Moorea and can be found hiding in coral rubble. They can also be referred to as the Bock's pygmy octopus. They are nocturnal and use camouflage as their primary defense against predators as well as to ambush their prey. Their typical prey are crustaceans, crabs, shrimp, and small fish and they can grow to be up to 10cm in size.

References

  1. ↑ Hanlon, Roger T. and Messenger, John B. (1999) Cephalopod Behaviour, p. 2. Cambridge University Press. ISBN   0-521-64583-2
  2. ↑ Boyle, Peter; Rodhouse, Paul (2004). Cephalopods : ecology and fisheries. Blackwell. doi:10.1002/9780470995310.ch2. ISBN   978-0-632-06048-1.
  3. ↑ Bush, Stephanie L.; Robison, Bruce H. (2007-09-01). "Ink utilization by mesopelagic squid". Marine Biology. 152 (3): 485–494. Bibcode:2007MarBi.152..485B. doi:10.1007/s00227-007-0684-2. ISSN   1432-1793. S2CID   84629175.
  4. ↑ Caldwell, Roy L. (2005). "An Observation of Inking Behavior Protecting Adult Octopus bocki from Predation by Green Turtle (Chelonia mydas) Hatchlings" (PDF). Pacific Science. 59: 69–72. doi:10.1353/psc.2005.0004. hdl: 10125/24161 . S2CID   54223984.
  5. ↑ Drerup, Christian; Sykes, António V.; Cooke, Gavan M. (2020-09-01). "Behavioural aspects of the spotty bobtail squid Euprymna parva (Cephalopoda: Sepiolidae)". Journal of Experimental Marine Biology and Ecology. 530–531: 151442. doi:10.1016/j.jembe.2020.151442. ISSN   0022-0981. S2CID   225286704.
  6. 1 2 3 4 Derby, C. D. (2007). "Escape by inking and secreting: Marine molluscs avoid predators through a rich array of chemicals and mechanisms" (PDF). The Biological Bulletin. 213 (3): 274–89. doi:10.2307/25066645. JSTOR   25066645. PMID   18083967. S2CID   9539618.
  7. ↑ Roper, Clyde F. E.; Jereb, P (2005). Cephalopods of the World: Chambered nautiluses and sepioids (Nautilidae, Sepiidae, Sepiolidae, Sepiadariidae, Idiosepiidae, and Spirulidae). Rome: Food and Agriculture Organization. p. 8. hdl:10088/9926. ISBN   9789251053836.
  8. ↑ Wood, James B.; Maynard, Amy E.; Lawlor, Alexandra G.; Sawyer, Eva K.; Simmons, Dawn M.; Pennoyer, Kelly E.; Derby, Charles D. (May 2010). "Caribbean reef squid, Sepioteuthis sepioidea, use ink as a defense against predatory French grunts, Haemulon flavolineatum". Journal of Experimental Marine Biology and Ecology. 388 (1–2): 20–27. doi:10.1016/j.jembe.2010.03.010.
  9. ↑ MacGinitie, G.E. and MacGinitie, N. (1968) Natural History of Marine Animals, pp. 395–397, 2nd ed. McGraw-Hill, New York.
  10. ↑ Wood, James B.; Pennoyer, Kelly E.; Derby, Charles D. (2008-11-30). "Ink is a conspecific alarm cue in the Caribbean reef squid, Sepioteuthis sepioidea". Journal of Experimental Marine Biology and Ecology. 367 (1): 11–16. doi:10.1016/j.jembe.2008.08.004. ISSN   0022-0981.
  11. ↑ Soto-Gómez, Diego; Pérez-Rodríguez, Paula; López-Periago, J. Eugenio; Paradelo, Marcos (2016). "Sepia ink as a surrogate for colloid transport tests in porous media". Journal of Contaminant Hydrology. 191: 88–98. Bibcode:2016JCHyd.191...88S. doi:10.1016/j.jconhyd.2016.05.005. PMID   27294674.
  12. ↑ Dilly, P. N.; Herring, Peter J. (2009-08-20). "The light organ and ink sac of Heteroteuthis dispar (Mollusca: Cephalopoda)". Journal of Zoology. 186 (1): 47–59. doi: 10.1111/j.1469-7998.1978.tb03356.x .
  13. 1 2 Derby, Charles D. (May 2014). "Cephalopod ink: Production, chemistry, functions, and applications". Marine Drugs. 12 (5). MDPI (published 2014-05-12): 2700–2730. doi: 10.3390/md12052700 . PMC   4052311 . PMID   24824020.
  14. ↑ Lucero, M.T.; Farrington, H.; Gilly, W.F. (August 1994). "Quantification of L-DOPA and dopamine in squid ink: Implications for chemoreception". The Biological Bulletin. 187 (1): 55–63. doi:10.2307/1542165. ISSN   0006-3185. JSTOR   1542165. PMID   29281314.
  15. 1 2 Ohigashi, Hajime; Osawa, Toshihiko; Terao, Junji; Watanabe, Shaw; Yoshikawa, Toshikazu, eds. (2013). Food Factors for Cancer Prevention. Springer. pp. 331, 336. ISBN   978-4-431-67017-9.
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