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All [[extant taxon|extant]] '''[[cephalopod]]s''' have a two-part '''beak''', or '''rostrum''', situated in the [[buccal mass]] and surrounded by the muscular [[Cephalopod limb|head appendages]]. The [[dorsal]] (upper) [[mandible]] fits into the [[ventral]] (lower) mandible and together they function in a scissor-like fashion.<ref name=ToL>Young, R.E., M. Vecchione & K.M. Mangold (1999). [http://tolweb.org/accessory/Cephalopoda_Glossary?acc_id=587 Cephalopoda Glossary]. [[Tree of Life Web Project]].</ref><ref>Young, R.E., M. Vecchione & K.M. Mangold (2000). [http://tolweb.org/accessory/Cephalopod_Beak_Terminology?acc_id=1980 Cephalopod Beak Terminology]. [[Tree of Life Web Project]].</ref> The beak is composed primarily of [[chitin]] and cross-linked [[protein]]s.<ref>Miserez, A., Y. Li, J.H. Waite & F. Zok (2007). {{PDFlink|[http://www.materials.ucsb.edu/~zok/PDF/JumboMiserez.pdf Jumbo squid beaks: Inspiration for design of robust organic composites.]}} ''Acta Biomaterialia'' '''3'''(1): 139–149. {{DOI|10.1016/j.actbio.2006.09.004}}</ref><ref>[http://www.asknature.org/strategy/c8582fcb160cdd74fe4872bfb8052458 Organic composite is exceptionally robust: jumbo squid]. Ask Nature.</ref>
All [[extant taxon|extant]] '''[[cephalopod]]s''' have a two-part '''beak''', or '''rostrum''', situated in the [[buccal mass]] and surrounded by the muscular [[Cephalopod limb|head appendages]]. The [[dorsal]] (upper) [[mandible]] fits into the [[ventral]] (lower) mandible and together they function in a scissor-like fashion.<ref name=ToL>Young, R.E., M. Vecchione & K.M. Mangold (1999). [http://tolweb.org/accessory/Cephalopoda_Glossary?acc_id=587 Cephalopoda Glossary]. [[Tree of Life Web Project]].</ref><ref>Young, R.E., M. Vecchione & K.M. Mangold (2000). [http://tolweb.org/accessory/Cephalopod_Beak_Terminology?acc_id=1980 Cephalopod Beak Terminology]. [[Tree of Life Web Project]].</ref> The beak is composed primarily of [[chitin]] and cross-linked [[protein]]s.<ref>Miserez, A., Y. Li, J.H. Waite & F. Zok (2007). {{PDFlink|[http://www.materials.ucsb.edu/~zok/PDF/JumboMiserez.pdf Jumbo squid beaks: Inspiration for design of robust organic composites.]}} ''Acta Biomaterialia'' '''3'''(1): 139–149. {{DOI|10.1016/j.actbio.2006.09.004}}</ref><ref>[http://www.asknature.org/strategy/c8582fcb160cdd74fe4872bfb8052458 Organic composite is exceptionally robust: jumbo squid]. Ask Nature.</ref>


Because they are more-or-less indigestible, beaks are often the only identifiable cephalopod remains found in the stomachs of predatory species such as [[sperm whale]]s.<ref>Clarke, M.R. (1986). ''A Handbook for the Identification of Cephalopod Beaks''. Oxford University Press, Oxford.</ref>
Because they are more-or-less indigestible, beaks are often the only identifiable cephalopod remains found in the stomachs of predatory species such as [[sperm whale]]s.<ref name=handbook>Clarke, M.R. (1986). ''A Handbook for the Identification of Cephalopod Beaks''. Oxford University Press, Oxford.</ref>

The abbreviations '''LRL''' and '''URL''' are commonly used in [[teuthology]] to refer to ''lower rostral length'' and ''upper rostral length'', respectively. This is the standard measure of beak size in [[Decapodiformes]]; ''hood length'' is preferred for [[Octopodiformes]].<ref name=handbook />


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Revision as of 13:58, 18 March 2012

The beak of a giant squid, surrounded by the buccal mass and limbs

All extant cephalopods have a two-part beak, or rostrum, situated in the buccal mass and surrounded by the muscular head appendages. The dorsal (upper) mandible fits into the ventral (lower) mandible and together they function in a scissor-like fashion.[1][2] The beak is composed primarily of chitin and cross-linked proteins.[3][4]

Because they are more-or-less indigestible, beaks are often the only identifiable cephalopod remains found in the stomachs of predatory species such as sperm whales.[5]

The abbreviations LRL and URL are commonly used in teuthology to refer to lower rostral length and upper rostral length, respectively. This is the standard measure of beak size in Decapodiformes; hood length is preferred for Octopodiformes.[5]

Anaglyph images of the upper (left) and lower mandibles of a female bigfin reef squid (Sepioteuthis lessoniana)
3D red cyan glasses are recommended to view this image correctly.
The upper (left) and lower jaws of a giant squid following extraction

References

  1. ^ Young, R.E., M. Vecchione & K.M. Mangold (1999). Cephalopoda Glossary. Tree of Life Web Project.
  2. ^ Young, R.E., M. Vecchione & K.M. Mangold (2000). Cephalopod Beak Terminology. Tree of Life Web Project.
  3. ^ Miserez, A., Y. Li, J.H. Waite & F. Zok (2007). Template:PDFlink Acta Biomaterialia 3(1): 139–149. doi:10.1016/j.actbio.2006.09.004
  4. ^ Organic composite is exceptionally robust: jumbo squid. Ask Nature.
  5. ^ a b Clarke, M.R. (1986). A Handbook for the Identification of Cephalopod Beaks. Oxford University Press, Oxford.
  • Clarke, M.R. (1962). The identification of cephalopod "beaks" and the relationship between beak size and total body weight. Bulletin of the British Museum (Natural History), Zoology 8(10): 419–480.
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