Ink sac
Anink sacis an anatomical feature that is found in manycephalopodmollusksused to produce the defensivecephalopod ink.With the exception of nocturnal and very deep watercephalopods,all Coleoidea (squid, octopus and cuttlefish) which dwell in light conditions have an ink sac, which can be used to expel a cloud of darkinkin order to confuse predators.[1]
The ink sac is a muscular bag which originated as an extension of the hind gut; it is a modifiedhypobranchial gland.[2]It lies beneath the gut and opens into the anus, into which its contents – almost puremelanin– can be squirted; its proximity to the base of the funnel means that the ink can be distributed by ejected water as the cephalopod uses its jet propulsion.[1]The ejected cloud of melanin is bound bymucusparticles, so it forms a lump approximately the size and shape of the cephalopod, fi xing the predator's attention while the mollusc itself makes a hasty escape.[1]
References
[edit]- ^abcBoyle, Peter; Rodhouse, Paul (2004).Cephalopods: ecology and fisheries.Ames, Iowa: Blackwell.doi:10.1002/9780470995310.ch2.ISBN0-632-06048-4.
- ^Nair, J.R., D. Pillai, S.M. Joseph, P. Gomathi, P.V. Senan & P.M. Sherief (2011)."Cephalopod research and bioactive substances"(PDF).Indian Journal of Geo-Marine Sciences40(1): 13–27.
Cephalopodanatomy | ||||||||||||||
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| Shell |
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| Mantle& funnel |
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| Head & limbs |
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| General |
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Developmental stages:Spawn→Paralarva(Doratopsis stage) → Juvenile → Subadult → Adult •Egg fossils•Protoconch (embryonic shell) | ||||||||||||||
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