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Cephalopod beak

From Wikipedia, in a visual modern way
The beak of a giant squid
The beak of a giant squid

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]

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]

Discover more about Cephalopod beak related topics

Cephalopod

Cephalopod

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.

Rostrum (anatomy)

Rostrum (anatomy)

Rostrum is a term used in anatomy for a number of phylogenetically unrelated structures in different groups of animals.

Cephalopod limb

Cephalopod limb

All cephalopods possess flexible limbs extending from their heads and surrounding their beaks. These appendages, which function as muscular hydrostats, have been variously termed arms, legs or tentacles.

Mandible

Mandible

In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone of the skull. It is connected to the temporal bones by the temporomandibular joints.

Squid

Squid

True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting these criteria. 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.

Octopus

Octopus

An octopus is a soft-bodied, eight-limbed mollusc of the order Octopoda. The order consists of some 300 species and is grouped within the class Cephalopoda with squids, 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 limbs. The soft body can radically alter its shape, enabling octopuses to squeeze through small gaps. They trail their eight appendages behind them as they swim. The siphon is used both for respiration and for locomotion, by expelling a jet of water. Octopuses have a complex nervous system and excellent sight, and are among the most intelligent and behaviourally diverse of all invertebrates.

Aptychus

Aptychus

An aptychus is a type of marine fossil. It is a hard anatomical structure, a sort of curved shelly plate, now understood to be part of the body of an ammonite. Paired aptychi have, on rare occasions, been found at or within the aperture of ammonite shells. The aptychus was usually composed of calcite, whereas the ammonite shell was aragonite.

Composition

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

Composed primarily of chitin and cross-linked proteins,[14][15][16][17] beaks are more-or-less indigestible and are often the only identifiable cephalopod remains found in the stomachs of predatory species such as sperm whales.[18] Cephalopod beaks gradually become less stiff as one moves from the tip to the base, a gradient that results from differing chemical composition. In hydrated beaks of the Humboldt squid (Dosidicus gigas) this stiffness gradient spans two orders of magnitude.[19]

  • Side view of the lower beak of Chiroteuthis picteti (3.6 mm LRL, 160 mm ML (estimate))[1] 3D red cyan glasses are recommended to view this image correctly.

    Side view of the lower beak of Chiroteuthis picteti (3.6 mm LRL, 160 mm ML (estimate))[1]
    3d glasses red cyan.svg 3D red cyan glasses are recommended to view this image correctly.

  • Side view of the upper beak from the same specimen (2.7 mm URL)[1]

    Side view of the upper beak from the same specimen (2.7 mm URL)[1]

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Giant squid

Giant squid

The giant squid is a species of deep-ocean dwelling squid in the family Architeuthidae. It can grow to a tremendous size, offering an example of abyssal gigantism: recent estimates put the maximum size at around 12–13 m (39–43 ft) for females and 10 m (33 ft) for males, from the posterior fins to the tip of the two long tentacles. The mantle of the giant squid is about 2 m long, and the length of the squid excluding its tentacles rarely exceeds 5 m (16 ft). Claims of specimens measuring 20 m (66 ft) or more have not been scientifically documented.

Chitin

Chitin

Chitin (C8H13O5N)n ( KY-tin) is a long-chain polymer of N-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chitin are produced each year in the biosphere. It is a primary component of cell walls in fungi (especially basidiomycetes and filamentous fungi), the exoskeletons of arthropods such as crustaceans and insects, the radulae, cephalopod beaks and gladii of molluscs and in some nematodes and diatoms. It is also synthesised by at least some fish and lissamphibians. Commercially, chitin is extracted from the shells of crabs, shrimps, shellfish and lobsters, which are major by-products of the seafood industry. The structure of chitin is comparable to cellulose, forming crystalline nanofibrils or whiskers. It is functionally comparable to the protein keratin. Chitin has proved useful for several medicinal, industrial and biotechnological purposes.

Protein

Protein

Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity.

Sperm whale

Sperm whale

The sperm whale or cachalot is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus Physeter and one of three extant species in the sperm whale family, along with the pygmy sperm whale and dwarf sperm whale of the genus Kogia.

Humboldt squid

Humboldt squid

The Humboldt squid, also known as jumbo squid or jumbo flying squid (EN), and Pota in Peru or Jibia in Chile (ES) is a large, predatory squid living in the eastern Pacific Ocean. It is the only known species of the genus Dosidicus of the subfamily Ommastrephinae, family Ommastrephidae.

Anaglyph 3D

Anaglyph 3D

Anaglyph 3D is the stereoscopic 3D effect achieved by means of encoding each eye's image using filters of different colors, typically red and cyan. Anaglyph 3D images contain two differently filtered colored images, one for each eye. When viewed through the "color-coded" "anaglyph glasses", each of the two images reaches the eye it's intended for, revealing an integrated stereoscopic image. The visual cortex of the brain fuses this into the perception of a three-dimensional scene or composition.

Measurements

Giant squid beak and associated muscles with hand for scale
Giant squid beak and associated muscles with hand for scale

The abbreviations LRL and URL are commonly used in teuthology to refer to lower rostral length and upper rostral length, respectively. These are the standard measures of beak size in Decapodiformes; hood length is preferred for Octopodiformes.[18] They can be used to estimate the mantle length and total body weight of the original animal as well as the total ingested biomass of the species.[20][21][22][23][24][25][26]

  • Lower rostral length

    Lower rostral length

  • Upper rostral length

    Upper rostral length


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Teuthology

Teuthology

Teuthology is the study of cephalopods such as octopus, squid, and cuttlefish.

Decapodiformes

Decapodiformes

Decapodiformes is a superorder of Cephalopoda comprising all cephalopod species with ten limbs, specifically eight short arms and two long tentacles. It is hypothesized that the ancestral coleoid had five identical pairs of limbs, and that one branch of descendants evolved a modified arm pair IV to become the Decapodiformes, while another branch of descendants evolved and then eventually lost its arm pair II, becoming the Octopodiformes.

Octopodiformes

Octopodiformes

Octopodiformes is a superorder of the subclass Coleoidea, comprising the octopuses and the vampire squid. All living members of Octopodiformes have eight arms, either lacking the two tentacles of squid or modifying the tentacles into thin filaments. Octopodiformes is often considered the crown group of octopuses and vampire squids, including all descendants of their common ancestor. Some authors use the term Vampyropoda for the same general category, though others use "Vampyropoda" to refer to the total group. Another term is Octobranchia, referring to cephalopods without prominent tentacles.

Mantle (mollusc)

Mantle (mollusc)

The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.

Biomass

Biomass

Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living organisms. In the latter context, there are variations in how biomass is defined, e.g. only from plants, or from plants and algae, or from plants and animals. The vast majority of biomass used for bioenergy does come from plants. Bioenergy is a type of renewable energy with potential to assist with climate change mitigation.

Source: "Cephalopod beak", Wikipedia, Wikimedia Foundation, (2022, October 27th), https://en.wikipedia.org/wiki/Cephalopod_beak.

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Further Reading

Squid

Cephalopod

Ammonoidea

Nectocaris

Belemnoidea

Nautiloid

Aptychus

Taningia danae

Cephalopod size

Cephalopod limb

Belemnotheutis

Seven-arm octopus

Muusoctopus levis

Belemnitida

Gladius (cephalopod)

Cephalopod fin

List of giant squid specimens and sightings (20th century)
References
  1. ^ a b c 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. ^ a b Tanabe, K., Y. Hikida & Y. Iba (2006). Two coleoid jaws from the Upper Cretaceous of Hokkaido, Japan. Journal of Paleontology 80(1): 138–145. doi:10.1666/0022-3360(2006)080[0138:TCJFTU2.0.CO;2]
  4. ^ Zakharov, Y.D. & T.A. Lominadze (1983). New data on the jaw apparatus of fossil cephalopods. Lethaia 16(1): 67–78. doi:10.1111/j.1502-3931.1983.tb02000.x
  5. ^ Kanie, Y. (1998). New vampyromorph (Coleoidea: Cephalopoda) jaw apparatuses from the Late Cretaceous of Japan. Bulletin of Gumma Museum of Natural History 2: 23–34.
  6. ^ Tanabe, K. & N.H. Landman (2002). Morphological diversity of the jaws of Cretaceous Ammonoidea. Abhandlungen der Geologischen Bundesanstalt, Wien 57: 157–165.
  7. ^ Tanabe, K., P. Trask, R. Ross & Y. Hikida (2008). Late Cretaceous octobrachiate coleoid lower jaws from the north Pacific regions. Journal of Paleontology 82(2): 398–408. doi:10.1666/07-029.1
  8. ^ 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). Lethaia 43(4): 445–456. doi:10.1111/j.1502-3931.2009.00203.x
  9. ^ Tanabe, K. (2012). Comparative morphology of modern and fossil coleoid jaw apparatuses. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 266(1): 9–18. doi:10.1127/0077-7749/2012/0243
  10. ^ Morton, N. (1981). Aptychi: the myth of the ammonite operculum. Lethaia 14(1): 57–61. doi:10.1111/j.1502-3931.1981.tb01074.x
  11. ^ Morton, N. & M. Nixon (1987). Size and function of ammonite aptychi in comparison with buccal masses of modem cephalopods. Lethaia 20(3): 231–238. doi:10.1111/j.1502-3931.1987.tb02043.x
  12. ^ Lehmann, U. & C. Kulicki (1990). Double function of aptychi (Ammonoidea) as jaw elements and opercula. Lethaia 23: 325–331. doi:10.1111/j.1502-3931.1990.tb01365.x
  13. ^ Seilacher, A. (1993). Ammonite aptychi; how to transform a jaw into an operculum? American Journal of Science 293: 20–32. doi:10.2475/ajs.293.A.20
  14. ^ Saunders, W.B., C. Spinosa, C. Teichert & R.C. Banks (1978). "The jaw apparatus of Recent Nautilus and its palaeontological implications" (PDF). Archived from the original (PDF) on 2016-10-05. Retrieved 2016-09-12. Palaeontology 21(1): 129–141.
  15. ^ Hunt, S. & M. Nixon (1981). A comparative study of protein composition in the chitin-protein complexes of the beak, pen, sucker disc, radula and oesophageal cuticle of cephalopods. Comparative Biochemistry and Physiology Part B: Comparative Biochemistry 68(4): 535–546. doi:10.1016/0305-0491(81)90071-7
  16. ^ Miserez, A., Y. Li, J.H. Waite & F. Zok (2007). "Jumbo squid beaks: Inspiration for design of robust organic composites" (PDF). Archived from the original (PDF) on 2016-03-05. Retrieved 2012-01-08. Acta Biomaterialia 3(1): 139–149. doi:10.1016/j.actbio.2006.09.004
  17. ^ Organic composite is exceptionally robust: jumbo squid Archived 2012-01-06 at the Wayback Machine. Ask Nature.
  18. ^ a b Clarke, M.R. (1986). A Handbook for the Identification of Cephalopod Beaks. Oxford University Press, Oxford.
  19. ^ Miserez, A., T. Schneberk, C. Sun, F.W. Zok & J.H. Waite (2008). The transition from stiff to compliant materials in squid beaks. Science 319(5871): 1816–1819. doi:10.1126/science.1154117
  20. ^ 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.
  21. ^ Wolff, G.A. (1981). "A beak key for eight eastern tropical Pacific cephalopod species with relationships between their beak dimensions and size" (PDF). Fishery Bulletin 80(2): 357–370.
  22. ^ Wolff, G.A. (1984). "Identification and estimation of size from the beaks of 18 species of cephalopods from the Pacific Ocean" (PDF). Archived from the original (PDF) on 2016-03-04. Retrieved 2013-02-03. NOAA Technical Report NMFS 17, NOAA/National Marine Fisheries Service.
  23. ^ Jackson, G.D. (1995). The use of beaks as tools for biomass estimation in the deepwater squid Moroteuthis ingens (Cephalopoda: Onychoteuthidae) in New Zealand waters. Polar Biology 15(1): 9–14. doi:10.1007/BF00236118
  24. ^ Jackson, G.D. & J.F. McKinnon (1996). Beak length analysis of arrow squid Nototodarus sloanii (Cephalopoda: Ommastrephidae) in southern New Zealand waters. Polar Biology 16(3): 227–230. doi:10.1007/BF02329211
  25. ^ Jackson, G.D., N.G. Buxton & M.J.A. George (1997). Beak length analysis of Moroteuthis ingens (Cephalopoda: Onychoteuthidae) from the Falkland Islands region of the Patagonian Shelf. Journal of the Marine Biological Association of the United Kingdom 77(4): 1235–1238. doi:10.1017/S0025315400038765
  26. ^ Gröger, J., U. Piatkowski & H. Heinemann (2000). "Beak length analysis of the Southern Ocean squid Psychroteuthis glacialis (Cephalopoda: Psychroteuthidae) and its use for size and biomass estimation". Polar Biology 23(1): 70–74. doi:10.1007/s003000050009
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