(invertebrate zoology) A subclass of cephalopod mollusks including all cephalopods except Nautilus, according to certain systems of classification.
Coleoidea
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(′kō·lē′öid·ē·ə)
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A subclass of the Cephalopoda that appeared in the middle Paleozoic (Early Devonian Period) and presumably evolved from the nautiloid stalk. Of the five orders of fossil coleoids, the belemnites are conspicuous with their fossilized shells termed lightning bolts. All these forms became extinct by the end of the Mesozoic, 65 million years ago. The surviving four orders that developed in the Late Triassic to Late Cretaceous represent all the living cephalopods today, except Nautilus (subclass Nautiloidea).
Coleoids are characterized by an internal chitinous or calcareous shell; 8–10 appendages around the mouth (8 arms and 2 tentacles when present) lined with suckers or hooks; one pair of gills; highly developed eyes; a fused, tubelike funnel; an ink sac (lost in some species); chromatophores; and fins on the body (lost in some octopuses).
The living coleoids are the order Sepioidea (cuttlefishes, like Sepia; bobtail squids, Spirula); the order Teuthoidea (squids—nearshore myopsids, like Loligo; open-ocean oegopsids, like Ommastrephes); the order Vampyromorpha (the black, deep-sea vampire squid); and the order Octopoda (octopuses, argonauts, deep-sea finned or cirrate octopods). Living coleoids generally are fast, mobile predators with an advanced brain and central nervous system. See also Belemnoidea; Cephalopoda; Mollusca; Nautiloidea; Sepioidea; Vampyromorpha.
| Wikipedia: Coleoidea |
| Coleoidea Fossil range: Devonian or Carboniferous - Recent |
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Subclass Coleoidea[1][2] is the grouping of cephalopods containing all the primarily soft-bodied creatures. Unlike its sister group Nautiloidea, whose members have a rigid outer shell for protection, the coleoids have at most an internal bone or shell that is used for buoyancy or support. Some species have lost their bone altogether, while in some it has been replaced by a cartilaginous support structure.
The major dividings of Coleoidea are based upon the number of arms or tentacles and their structure. The extinct and most primitive form, the Belemnoidea, presumably had ten equally sized arms, in five pairs numbered dorsal to ventral as I, II, III, IV and V. More modern species either modified or lost a pair of arms. The superorder Decapodiformes has arm pair IV modified into long tentacles with suckers generally only on the club-shaped distal end. Superorder Octopodiformes has modifications to arm pair II; it is significantly reduced and used only as a sensory filament in the Vampyromorphida, while Octopoda species have totally lost that arm pair.
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Evolutionary history
The earliest certain coleoids are known from the Mississippian sub-period of the Carboniferous Period, about 330 million years ago. Some older fossils have been described from the Devonian,[3] but paleontologists disagree about whether they are coleoids.[4]
By the Carboniferous, coleoids already had a diversity of forms. Although most of these groups are traditionally classified as belemnoids, the variation among them suggests that some are not closely related to belemnites.[5]
Classification
- Class Cephalopoda
- Subclass Nautiloidea: nautilus
- Subclass †Ammonoidea: ammonites
- Subclass Coleoidea
- Division †Belemnoidea: extinct belemnoids
- Genus †Jeletzkya
- Order †Hematitida
- Order †Phragmoteuthida
- Order †Donovaniconida
- Order †Aulacocerida
- Order †Belemnitida
- Division Neocoleoidea
- Superorder Decapodiformes
- ?Order †Boletzkyida
- Order Spirulida: Ram's Horn Squid
- Order Sepiida: cuttlefish
- Order Sepiolida: bobtail squid
- Order Teuthida: squid
- Superorder Octopodiformes
- Order Vampyromorphida: Vampire Squid
- Order Octopoda: octopus
- Superorder Decapodiformes
- Division †Belemnoidea: extinct belemnoids
References
- ^ From Greek keleos, sheath
- ^ Marion Nixon and J.Z. Young. (2003). The brains and lives of cephalopods. New York: Oxford University Press. ISBN 0-19-852761-6.
- ^ Bandel, Klaus, Reitner, J., & Sturmer, W. (1983). "Coleoidea from the Lower Devonian Black Slate ("Hunsruck-Schiefer")". Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen (Stuttgart) 165 (3): 397-417.
- ^ Nishiguchi, Michelle, & Mapes, Royal K. (2008), "Cephalopoda", in Ponder, Winston F., & Lindberg, David R., Phylogeny and evolution of the Mollusca, Dordrecht, The Netherlands: Springer, pp. 163-199, ISBN 978-0520250925
- ^ Doguzhaeva, Larisa A., Mapes, Royal H., & Mutvei, Harry (2007), "A Late Carboniferous Coleoid Cephalopod from the Mazon Creek Lagerstätte (USA) with a radula, arm hooks, mantle tissues, and ink", in Landman, Neil H., Davis, Richard Arnold, & Mapes, Royal H., Cephalopods Present & Past: New Insights and Fresh Perspectives, Berkeley & Los Angeles, California, USA: University of California Press, pp. 121-143
- Bather, F.A. (1888). "Shell-growth in Cephalopoda (Siphonopoda)". Annals and Magazine of Natural History 6 (1): 298–310.
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Mentioned in
- Teuthoidea (invertebrate zoology)
- Sepioidea (invertebrate zoology)
- Octopoda
- Squid (mollusca)
