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 may also be referred to as the mandibles or jaws.[3] These beaks are different from bird beaks because it crushes bone while most birds don't.
Fossilised remains of beaks are known from a number of cephalopod groups, both extant and extinct, including squids, octopuses, belemnites, and vampyromorphs.[3][4][5][6][7][8][9] Aptychi – paired plate-like structures found in ammonites – may also have been jaw elements.[10][11][12][13]
^Young, R.E., M. Vecchione & K.M. Mangold (1999). Cephalopoda Glossary. Tree of Life Web Project.
^Young, R.E., M. Vecchione & K.M. Mangold (2000). Cephalopod Beak Terminology. Tree of Life Web Project.
^ abTanabe, K., Y. Hikida & Y. Iba (2006). Two coleoid jaws from the Upper Cretaceous of Hokkaido, Japan. Journal of Paleontology80(1): 138–145. doi:10.1666/0022-3360(2006)080[0138:TCJFTU2.0.CO;2]
^Zakharov, Y.D. & T.A. Lominadze (1983). New data on the jaw apparatus of fossil cephalopods. Lethaia16(1): 67–78. doi:10.1111/j.1502-3931.1983.tb02000.x
^Kanie, Y. (1998). New vampyromorph (Coleoidea: Cephalopoda) jaw apparatuses from the Late Cretaceous of Japan. Bulletin of Gumma Museum of Natural History2: 23–34.
^Tanabe, K. & N.H. Landman (2002). Morphological diversity of the jaws of Cretaceous Ammonoidea. Abhandlungen der Geologischen Bundesanstalt, Wien57: 157–165.
^Tanabe, K., P. Trask, R. Ross & Y. Hikida (2008). Late Cretaceous octobrachiate coleoid lower jaws from the north Pacific regions. Journal of Paleontology82(2): 398–408. doi:10.1666/07-029.1
^Klug, C., G. Schweigert, D. Fuchs & G. Dietl (2010). First record of a belemnite preserved with beaks, arms and ink sac from the Nusplingen Lithographic Limestone (Kimmeridgian, SW Germany). Lethaia43(4): 445–456. doi:10.1111/j.1502-3931.2009.00203.x
^Tanabe, K. (2012). Comparative morphology of modern and fossil coleoid jaw apparatuses. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen266(1): 9–18. doi:10.1127/0077-7749/2012/0243
^Morton, N. (1981). Aptychi: the myth of the ammonite operculum. Lethaia14(1): 57–61. doi:10.1111/j.1502-3931.1981.tb01074.x
^Morton, N. & M. Nixon (1987). Size and function of ammonite aptychi in comparison with buccal masses of modem cephalopods. Lethaia20(3): 231–238. doi:10.1111/j.1502-3931.1987.tb02043.x
^Lehmann, U. & C. Kulicki (1990). Double function of aptychi (Ammonoidea) as jaw elements and opercula. Lethaia23: 325–331. doi:10.1111/j.1502-3931.1990.tb01365.x
^Seilacher, A. (1993). Ammonite aptychi; how to transform a jaw into an operculum? American Journal of Science293: 20–32. doi:10.2475/ajs.293.A.20
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)...
needed] The cephalopodbeak resembles that of a parrot. It is a tough structure made of chitin and marks the beginning of the cephalopod's digestive system...
A cephalopod /ˈsɛfələpɒd/ is any member of the molluscan class Cephalopoda /sɛfəˈlɒpədə/ (Greek plural κεφαλόποδες, kephalópodes; "head-feet") such as...
All cephalopods possess flexible limbs extending from their heads and surrounding their beaks. These appendages, which function as muscular hydrostats...
echidnas and platypuses, which have a beak-like structure), sirens, pufferfish, billfishes and cephalopods. Although beaks vary significantly in size, shape...
0273 Wolff, G.A. (1981). A beak key for eight eastern tropical Pacific cephalopod species with relationships between their beak dimensions and size. Fishery...
Atlas of cephalopod distribution in the Southern Ocean". Antarctic Science 11:61-62. online version Xavier, J.C. & Y. Cherel (2009). "CephalopodBeak Guide...
exoskeletons of arthropods such as crustaceans and insects, the radulae, cephalopodbeaks and gladii of molluscs and in some nematodes and diatoms. It is also...
this species. Studies measuring the δ15N content of the chitinous beaks of cephalopods to determine trophic ecology levels have demonstrated that the colossal...
crest length, is mentioned in A Handbook for the Identification of CephalopodBeaks. A. argo is cosmopolitan, occurring in tropical and subtropical waters...
barnacles. Like all cephalopods, squids are predators and have complex digestive systems. The mouth is equipped with a sharp, horny beak mainly made of chitin...
been strong enough to breach the prey's exoskeleton or shell. Modern cephalopodsbeaks contain a radula, or 'toothed' tongue, which is used to rasp out soft...
beak, as in other cephalopods.[citation needed] Giant squid have small fins at the rear of their mantles used for locomotion. Like other cephalopods,...
cuttlefish, and nautiloids. Like other cephalopods, an octopus is bilaterally symmetric with two eyes and a beaked mouth at the center point of the eight...
between cuttlefish and almost all other cephalopods allows them to produce venom, excreting it through their beak to help kill their prey. Additionally...
ναυτίλος nautílos 'sailor') is an ancient pelagic marine mollusc of the cephalopod family Nautilidae. The nautilus is the sole extant family of the superfamily...
fish, and about 10 percent was cephalopods. The researchers concluded that the number of fish otoliths and cephalopodbeaks indicated the importance of these...
pinniped diets: Accounting for complete digestion of otoliths and cephalopodbeaks". Canadian Journal of Fisheries and Aquatic Sciences. 57 (5): 898–905...
dofleini), also known as the North Pacific giant octopus, is a large marine cephalopod belonging to the genus Enteroctopus and Enteroctopodidae family. Its spatial...
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