Coleoidea

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Coleoidea
Temporal range: Devonian or Carboniferous –Recent
Cuttlefish komodo large.jpg
A cuttlefish
Octopus vulgaris2.jpg
A common octopus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Clade: Neocephalopoda
Subclass: Coleoidea
Bather, 1888
Divisions

Coleoidea [1] [2] or Dibranchiata is one of the two subclasses of cephalopods containing all the various taxa popularly thought of as "soft-bodied" or "shell-less" (i.e. octopus, squid and cuttlefish). Unlike its extant sister group Nautiloidea, whose members have a rigid outer shell for protection, the coleoids have at most an internal shell called cuttlebone or gladius that is used for buoyancy or as muscle anchorage. Some species, notably incirrate octopuses, have lost their cuttlebone altogether, while in some it has been replaced by a chitinous support structure. A unique trait of the group is the ability to edit their own RNA. [3]

Contents

The major divisions 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. The inner surface of the suckers (acetabulum) are reinforced with rigid sucker rings which are smooth in Sepiolida, have blunt teeth in Sepiida and sharply pointed teeth in Loliginidae and Oegopsida. The arms and/or tentacles of some oegopsid families have also evolved claw-like hooks. [4]

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, [5] but paleontologists disagree about whether they are coleoids. [6] Other cephalopods with internal shells, which could represent coleoids but may also denote the independent internalization of the shell, are known from the Silurian. [7] It has been hypothesized that the Early–Middle Cambrian fossil Nectocaris represents a coleoid (or other cephalopod) that lost its shell, possibly secondarily, [8] [9] although it is more likely that Nectocaris represents an independent lineage within the Lophotrochozoa. [10]

By the Carboniferous, coleoids already had a diversity of forms, but the major radiation happened during the Tertiary. [11] Although most of these groups are traditionally classified as belemnoids, the variation among them suggests that some are not closely related to belemnites. [12]

Classification

Related Research Articles

<span class="mw-page-title-main">Squid</span> Superorder of cephalopod molluscs

A squid is a mollusc 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.

<span class="mw-page-title-main">Cephalopod</span> Class of mollusks

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.

<span class="mw-page-title-main">Vampire squid</span> Species of cephalopod

The vampire squid is a small cephalopod found throughout temperate and tropical oceans in extreme deep sea conditions. The vampire squid uses its bioluminescent organs and its unique oxygen metabolism to thrive in the parts of the ocean with the lowest concentrations of oxygen. It has two long retractile filaments, located between the first two pairs of arms on its dorsal side, which distinguish it from both octopuses and squids, and places it in its own order, Vampyromorphida, although its closest relatives are octopods. As a phylogenetic relict, it is the only known surviving member of its order.

<span class="mw-page-title-main">Bobtail squid</span> Order cephalopod molluscs closely related to cuttlefish

Bobtail squid are a group of cephalopods closely related to cuttlefish. Bobtail squid tend to have a rounder mantle than cuttlefish and have no cuttlebone. They have eight suckered arms and two tentacles and are generally quite small.

<span class="mw-page-title-main">Oegopsida</span> Order of squids

Oegopsida is one of the two orders of squid in the superorder Decapodiformes, in the class Cephalopoda. Together with the Myopsina, it was formerly considered to be a suborder of the order Teuthida, in which case it was known as Oegopsina. This reclassification is due to Oegopsina and Myopsina not being demonstrated to form a clade.

<span class="mw-page-title-main">Belemnoidea</span> Extinct group of squid-like animals

Belemnoids are an extinct group of marine cephalopod, very similar in many ways to the modern squid. Like them, the belemnoids possessed an ink sac, but, unlike the squid, they possessed ten arms of roughly equal length, and no tentacles. The name "belemnoid" comes from the Greek word βέλεμνον, belemnon meaning "a dart or arrow" and the Greek word είδος, eidos meaning "form".

<span class="mw-page-title-main">Nautiloid</span> Extant subclass of cephalopods

Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living Nautilus and Allonautilus. Fossil nautiloids are diverse and speciose, with over 2,500 recorded species. They flourished during the early Paleozoic era, when they constituted the main predatory animals. Early in their evolution, nautiloids developed an extraordinary diversity of shell shapes, including coiled morphologies and giant straight-shelled forms (orthocones). Only a handful of rare coiled species, the nautiluses, survive to the present day.

<span class="mw-page-title-main">Decapodiformes</span> Superorder of Cephalopoda

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.

<span class="mw-page-title-main">Cirrina</span> Suborder of octopuses

Cirrina or Cirrata is a suborder and one of the two main divisions of octopuses. Cirrate octopuses have a small, internal shell and two fins on their head, while their sister suborder Incirrina has neither. The fins of cirrate octopods are associated with a unique cartilage-like shell in a shell sac. In cross-section, the fins have distinct proximal and distal regions, both of which are covered by a thin surface sheath of muscle.

<span class="mw-page-title-main">Incirrata</span> Suborder of octopuses

Incirrata is a suborder of the order Octopoda. The suborder contains the classic "benthic octopuses," as well as many pelagic octopus families, including the paper nautiluses. The incirrate octopuses are distinguished from the cirrate octopuses by the absence in the former of the "cirri" filaments for which the cirrates are named, as well as by the lack of paired swimming fins on the head, and lack of a small internal shell.

<span class="mw-page-title-main">Octopodiformes</span> Superorder of molluscs

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.

<span class="mw-page-title-main">Cephalopod limb</span> Limbs of cephalopod molluscs

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.

<span class="mw-page-title-main">Neocoleoidea</span> Group of molluscs

Neocoleoidea is a large group of marine cephalopods. This cohort contains two extant groups: Decapodiformes and Octopodiformes. Species within this group exist in all major habitats in the ocean, in both the southern and northern polar regions, and from intertidal zones to great depths. Whilst conventionally held to be monophyletic, the only morphological character for the group is the presence of suckers: although the presence of these features in the belemnites suggests that they do not support the Neocoleoidea, and hence that the group may be paraphyletic.

<span class="mw-page-title-main">Orthoceratoidea</span> Extinct subclass of cephalopods

Orthoceratoidea is a major subclass of nautiloid cephalopods. Members of this subclass usually have orthoconic (straight) to slightly cyrtoconic (curved) shells, and central to subcentral siphuncles which may bear internal deposits. Orthoceratoids are also characterized by dorsomyarian muscle scars, extensive cameral deposits, and calciosiphonate connecting rings with a porous and calcitic inner layer.

<span class="mw-page-title-main">Phragmoteuthida</span> Extinct order of molluscs

Phragmoteuthida is an order of extinct coleoid cephalopods characterized by a fan-like teuthoid pro-ostracum attached to a belemnoid-like phragmocone.

<span class="mw-page-title-main">Belemnitida</span> Extinct, squid-like, Mesozoic cephalopods

Belemnitida is an extinct order of squid-like cephalopods that existed from the Late Triassic to Late Cretaceous. Unlike squid, belemnites had an internal skeleton that made up the cone. The parts are, from the arms-most to the tip: the tongue-shaped pro-ostracum, the conical phragmocone, and the pointy guard. The calcitic guard is the most common belemnite remain. Belemnites, in life, are thought to have had 10 hooked arms and a pair of fins on the guard. The chitinous hooks were usually no bigger than 5 mm (0.20 in), though a belemnite could have had between 100 and 800 hooks in total, using them to stab and hold onto prey.

<span class="mw-page-title-main">Gladius (cephalopod)</span> Bodypart of certain cephalopods

The gladius, or pen, is a hard internal bodypart found in many cephalopods of the superorder Decapodiformes and in a single extant member of the Octopodiformes, the vampire squid. It is so named for its superficial resemblance to the Roman short sword of the same name, and is a vestige of the ancestral mollusc shell, which was external. The gladius is located dorsally within the mantle and usually extends for its entire length. Composed primarily of chitin, it lies within the shell sac, which is responsible for its secretion.

<span class="mw-page-title-main">Argonautoidea</span> Superfamily of octopuses

Argonautoidea is a superfamily of the suborder Incirrata containing all known argonautoids.

<i>Syllipsimopodi</i> Genus of fossil coleoid

Syllipsimopodi is an extinct member of the cephalopod subclass Coleoidea originally interpreted to belong to the clade Vampyropoda, which includes octopuses (Octopoda) and vampire squids (Vampyromorphida). The type and only known species is Syllipsimopodi bideni, named in honor of US President Joe Biden, and to raise awareness of his climate change policies. The holotype fossil was found in the Bear Gulch Limestone deposit in the US state of Montana in 1988, and donated that year to the Royal Ontario Museum by B. Hawes, designated ROMIP 64897. The species lived during the (Carboniferous) Mississippian subperiod, 330.3 to 323.4 million years ago, pushing back the group of cephalopods by 81.9 million years.

References

  1. From Greek koleos, sheath
  2. Nixon, Marion; Young, J. Z. (2003). The Brains and Lives of Cephalopods. New York: Oxford University Press. ISBN   978-0-19-852761-9.
  3. Octopus And Squid Evolution Is Officially Weirder Than We Could Have Ever Imagined
  4. Evolutionary development of the cephalopod arm armature: a review
  5. Bandel, Klaus; Reitner, J.; Sturmer, W. (1983). "Coleoids from the Lower Devonian Black Slate ("Hunsruck-Schiefer")". Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 165 (3): 397–417.
  6. Zuschin, Martin (2008). "Phylogeny and Evolution of the Mollusca". Marine Ecology. 30 (2): 269. Bibcode:2009MarEc..30..269Z. doi:10.1111/j.1439-0485.2009.00287.x.
  7. Turek, V.; Manda, Š. (2012). "An endocochleate experiment in the Silurian straight-shelled cephalopod Sphooceras". Bulletin of Geosciences. 87 (4): 767–813. doi: 10.3140/bull.geosci.1335 .
  8. Smith, M. R.; Caron, J. B. (2010). "Primitive soft-bodied cephalopods from the Cambrian". Nature. 465 (7297): 469–472. Bibcode:2010Natur.465..469S. doi:10.1038/nature09068. hdl: 1807/32368 . PMID   20505727. S2CID   4421029.
  9. Smith, M. R. (2013). "Nectocaridid ecology, diversity and affinity: early origin of a cephalopod-like body plan". Paleobiology. 39 (2): 291–321. doi:10.1666/12029. S2CID   85744624.
  10. Kröger, Björn; Vinther, Jakob; Fuchs, Dirk (August 2011). "Cephalopod origin and evolution: A congruent picture emerging from fossils, development and molecules: Extant cephalopods are younger than previously realised and were under major selection to become agile, shell-less predators". BioEssays. 33 (8): 602–613. doi:10.1002/bies.201100001. PMID   21681989. S2CID   2767810.
  11. Cephalopods: Ecology and Fisheries
  12. 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. (eds.). Cephalopods Present & Past: New Insights and Fresh Perspectives. Berkeley & Los Angeles, California, USA: University of California Press. pp. 121–143.
  13. Garassino, A.; Donovan, D. T. (2000). "A New Family of Coleoids from the Lower Jurassic of Osteno, Northern Italy". Palaeontology. 43 (6): 1019. doi: 10.1111/1475-4983.00160 .