Cephalopod ink

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]

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.

^ Hanlon, Roger T. and Messenger, John B. (1999) Cephalopod Behaviour, p. 2. Cambridge University Press. ISBN 0-521-64583-2
^ Boyle, Peter; Rodhouse, Paul (2004). Cephalopods : ecology and fisheries. Blackwell. doi:10.1002/9780470995310.ch2. ISBN 978-0-632-06048-1.

[1] Hanlon, Roger T. and Messenger, John B. (1999) Cephalopod Behaviour, p. 2. Cambridge University Press. ISBN 0-521-64583-2

[Boyle-2] Boyle, Peter; Rodhouse, Paul (2004). Cephalopods : ecology and fisheries. Blackwell. doi:10.1002/9780470995310.ch2. ISBN 978-0-632-06048-1.

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