{{Short description|Subclass of cephalopods}} {{Automatic taxobox |fossil_range=Devonian or {{fossil range |earliest=Devonian |Carboniferous |Recent}} |image=Cuttlefish komodo large.jpg |image_caption=A cuttlefish (Decapodiformes) |image2=Octopus vulgaris2.jpg |image2_caption=A common octopus (Octopodiformes) |parent_authority=Bather, 1888 |taxon=Neocoleoidea |authority={{ill|Winfried Haas|de|lt=Haas}}, 1997 |subdivision_ranks=Divisions |subdivision= See text }}
'''Coleoidea'''<ref>From Greek ''koleos''; sheath</ref><ref name=Cephalopods> {{cite book |last1=Nixon |first1=Marion |last2=Young |first2=J. Z. |author2-link=John Zachary Young |year=2003 |title=The Brains and Lives of Cephalopods |location=New York |publisher=Oxford University Press |isbn=978-0-19-852761-9}}</ref> or '''Dibranchiata''' is one of the two subclasses of cephalopod molluscs containing all the various taxa popularly thought of as "soft-bodied" or "shell-less" (i.e. octopus, squid and cuttlefish). Unlike its sister groups, the shelled {{extinct}}Ammonoidea and Nautiloidea, the '''coleoids''' have at most an internal shell called cuttlebone or gladius that is used for buoyancy or as muscle attachment. Some species, notably the incirrate octopuses (including commonly known varieties living in the shallows), have lost their internal shell altogether, while in some it has been replaced by a chitinous support structure.{{Example needed|date=July 2025}}
==Etymology== Coleoidea comes from the greek word ''koleos''. The term Dibranchiata comes from the Greek words “di,” meaning “two,” and “branchion,” which comes from “branchia,” meaning “gill.”
==Evolution== 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,<ref name="Bandel et al. 1983"> {{cite journal |last1=Bandel |first1=Klaus |last2=Reitner |first2=J. |last3=Sturmer |first3=W. |year=1983 |title=Coleoids from the Lower Devonian Black Slate ("Hunsruck-Schiefer") |journal=Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen |volume=165 |issue=3 |pages=397–417|doi=10.1127/njgpa/165/1983/397 }}</ref> but paleontologists disagree about whether they are coleoids.<ref name="Nishighuchi & Mapes 2008"> {{Cite journal |last1=Zuschin |first1=Martin |year=2008 |title=Phylogeny and Evolution of the Mollusca |journal=Marine Ecology |volume=30 |issue=2 |page=269 |bibcode=2009MarEc..30..269Z |doi=10.1111/j.1439-0485.2009.00287.x}}</ref> Other cephalopods with internal shells, which could represent coleoids but may also denote the independent internalization of the shell, are known from the Silurian.<ref> {{Cite journal |last1=Turek |first1=V. |last2=Manda |first2=Š. |title=An endocochleate experiment in the Silurian straight-shelled cephalopod ''Sphooceras'' |year=2012 |journal=Bulletin of Geosciences |volume=87 |issue=4 |pages=767–813 |doi=10.3140/bull.geosci.1335 |doi-access=free}}</ref> It has been hypothesized that the Early–Middle Cambrian fossil ''Nectocaris'' represents a coleoid (or other cephalopod) that lost its shell, possibly secondarily,<ref name="Smith2010">{{Cite journal |last1=Smith |first1=M. R. |last2=Caron |first2=J. B. |title=Primitive soft-bodied cephalopods from the Cambrian |year=2010 |journal=Nature |volume=465 |issue=7297 |pages=469–472 |bibcode=2010Natur.465..469S |doi=10.1038/nature09068 |hdl=1807/32368 |hdl-access=free |pmid=20505727 |s2cid=4421029|url=https://durham-repository.worktribe.com/output/1430329 }}</ref><ref name="Smith2013">{{cite journal |last1=Smith |first1=M. R. |year=2013 |title=Nectocaridid ecology, diversity and affinity: early origin of a cephalopod-like body plan |journal=Paleobiology |volume=39 |issue=2 |pages=291–321 |doi=10.1666/12029 |bibcode=2013Pbio...39..297S |s2cid=85744624}}</ref> but it is later identified as relatives of modern chaetognaths (arrow worms).<ref name=":2">{{Cite journal |last1=Vinther |first1=Jakob |last2=Parry |first2=Luke A. |last3=Lee |first3=Mirinae |last4=Nielsen |first4=Morten Lunde |last5=Oh |first5=Yeongju |last6=Park |first6=Changkun |last7=Kihm |first7=Ji-Hoon |last8=DeVivo |first8=Giacinto |last9=Harper |first9=David A. T. |last10=Nielsen |first10=Arne T. |last11=Park |first11=Tae-Yoon S. |date=2025-07-25 |title=A fossilized ventral ganglion reveals a chaetognath affinity for Cambrian nectocaridids |journal=Science Advances |language=en |volume=11 |issue=30 |article-number=eadu6990 |doi=10.1126/sciadv.adu6990 |pmid=40700488 |issn=2375-2548 |pmc=12285702}}</ref>
By the Carboniferous, coleoids already had a diversity of forms, but the major radiation happened during the Tertiary.<ref>{{cite book | url=https://books.google.com/books?id=k3aBFSVUXqEC&dq=fossil+belemnites%2C+major+radiation+of+the+group+Tertiary&pg=PA42 | title=Cephalopods: Ecology and Fisheries | isbn=978-1-4051-4543-5 | last1=Boyle | first1=Peter | last2=Rodhouse | first2=Paul | date=15 April 2008 | publisher=John Wiley & Sons }}</ref> Although most of these groups are traditionally classified as belemnoids, the variation among them suggests that some are not closely related to belemnites.<ref name="Dougushaeva et al. 2007"> {{Cite book |last1=Doguzhaeva |first1=Larisa A. |last2=Mapes |first2=Royal H. |last3=Mutvei |first3=Harry |year=2007 |chapter=A Late Carboniferous Coleoid Cephalopod from the Mazon Creek Lagerstätte (USA) with a radula, arm hooks, mantle tissues, and ink |editor1-last=Landman |editor1-first=Neil H. |editor2-last=Davis |editor2-first=Richard Arnold |editor3-last=Mapes |editor3-first=Royal H. |title=Cephalopods Present & Past: New Insights and Fresh Perspectives |pages=121–143 |location=Berkeley & Los Angeles, California, USA |publisher=University of California Press}}</ref>
===Classification=== The major divisions within 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 as (counting from dorsal to ventral pairs) I, II, III, IV and V. More modern species either modified or lost a pair of arms; the superorder Decapodiformes (literally "ten arms" in greek) 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 species of Octopods (literally "eight arms") 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, such as the hooked squid and the colossal squid.<ref>{{cite journal | pmc=8688392 | date=2021 | last1=Fuchs | first1=D. | last2=Hoffmann | first2=R. | last3=Klug | first3=C. | title=Evolutionary development of the cephalopod arm armature: A review | journal=Swiss Journal of Palaeontology | volume=140 | issue=1 | page=27 | doi=10.1186/s13358-021-00241-z | doi-access=free | pmid=34956072 | bibcode=2021SwJP..140...27F }}</ref>
Subordinate to Coleoidea is the division/cohort; '''Neocoleoidea''', containing two extant groups: Decapodiformes (squid, cuttlefish, and relatives) and Octopodiformes (octopuses and the vampire squid). 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 the deep sea.<ref>{{cite web|url=http://tolweb.org/coleoidea/19400 |title=Coleoidea |publisher=Tolweb.org |date=2008-04-21 |access-date=2010-07-30}}</ref> Whilst conventionally held to be monophyletic and thus a "natural" clade, the only morphological character for the group is the presence of suckers, the discovery of these features in the belemnites suggests that Neocoleoidea may be paraphyletic: the definition of the group excludes species that are closer related to some Neocoleoids than these are to others within the group.<ref name="Fuchs2010">{{Cite journal | last1 = Fuchs | first1 = D. | last2 = Von Boletzky | first2 = S. | last3 = Tischlinger | first3 = H. | title = New evidence of functional suckers in belemnoid coleoids (Cephalopoda) weakens support for the 'Neocoleoidea' concept | doi = 10.1093/mollus/eyq032 | journal = Journal of Molluscan Studies | volume = 76 | pages = 404–406 | year = 2010 | issue = 4 | doi-access = free }}</ref>
*Class Cephalopoda **Subclass Nautiloidea: nautilus **Subclass †Ammonoidea: ammonites **'''Subclass Coleoidea''' ***Division †Belemnoidea: extinct belemnoids ****Genus †''Jeletzkya''<!-- Palaeontology43(5): 919-926 --> ****Order †Hematitida ****Order †Phragmoteuthida ****Order †Donovaniconida ****Order †Aulacocerida ****Order †Belemnitida ***Division '''Neocoleoidea''' ****Superorder Decapodiformes *****Order Bathyteuthida *****Order †Belemnitida *****Order †Diplobelida *****Order Idiosepida – pygmy squid *****Order Myopsida – coastal squid *****Order Oegopsida – neritic squid *****Order Sepiida – cuttlefish, bottletail, and bobtail squid *****Order Spirulida – ram's horn squid ****Superorder Octopodiformes *****Family †Trachyteuthididae <small>(''incertae sedis'')</small> *****Order Vampyromorphida: vampire squid *****Order Octopoda: octopus ****Superorder Palaeoteuthomorpha *****Order †Boletzkyida *** (uncertain order) **** family †Ostenoteuthidae<ref name="Garassino 2000"> {{Cite journal |last1=Garassino |first1=A. |last2=Donovan |first2=D. T. |year=2000 |title=A New Family of Coleoids from the Lower Jurassic of Osteno, Northern Italy |journal=Palaeontology |volume=43 |issue=6 |page=1019 |doi=10.1111/1475-4983.00160 |doi-access=free |bibcode=2000Palgy..43.1019G }}</ref>
==Reproduction== The majority of coleoid species are semelparous; dying after reproducing once, with males dying after insemination, and females dying after laying/brooding their clutch.<ref name="Strat"/> A few species do not conform to this trend however; vampire squid, large Pacific striped octopus, and the West Atlantic scaled squid are thought to be iteroparous.<ref name="Vamp">{{cite journal |last1=Hoving |first1=Henk-Jan T. |last2=Laptikhovsky |first2=Vladimir V. |last3=Robison |first3=Bruce H. |title=Vampire squid reproductive strategy is unique among coleoid cephalopods |journal=Current Biology |date=20 April 2015 |volume=25 |issue=8 |pages=R322–R323 |url=https://oceanrep.geomar.de/28773/1/Hoving%2C%20Laptikhovsky%20and%20Robison%202015.pdf |access-date=29 July 2020 |doi=10.1016/j.cub.2015.02.018 |pmid=25898098 |s2cid=668950|doi-access=free |bibcode=2015CBio...25.R322H }}</ref><ref name="LPSO">{{Cite journal|last1=Caldwell|first1=Roy L.|last2=Ross|first2=Richard|last3=Rodaniche|first3=Arcadio|last4=Huffard|first4=Christine L.|date=12 August 2015|title=Behavior and Body Patterns of the Larger Pacific Striped Octopus|journal=PLOS ONE|language=en|volume=10|issue=8|article-number=e0134152|doi=10.1371/journal.pone.0134152|issn=1932-6203|pmc=4534201|pmid=26266543|bibcode=2015PLoSO..1034152C|doi-access=free}}</ref><ref name="Phol">{{cite journal |last1=Hoving |first1=H. J. T. |last2=Vecchione |first2=M. |title=Mating Behavior of a Deep-Sea Squid Revealed by in situ Videography and the Study of Archived Specimens |journal=The Biological Bulletin, University of Chicago |date=December 2012 |volume=223 |issue=3 |pages=263–267 |url=https://www.journals.uchicago.edu/doi/full/10.1086/BBLv223n3p263 |doi=10.1086/BBLv223n3p263 |pmid=23264472 |access-date=30 March 2025|url-access=subscription }}</ref> This is somewhat comparable to extant nautilus, which are also iteroparous, being long-lived animals.<ref name="Strat"/><ref name="Longe">{{cite journal |author=Saunders WB |title=Nautilus Growth and Longevity: Evidence from Marked and Recaptured Animals |journal=Science |volume=224 |issue=4652 |pages=990–992 |date=June 1984 |pmid=17731999 |doi=10.1126/science.224.4652.990 |bibcode = 1984Sci...224..990S |s2cid=40891271 }}</ref>
Some authors prefer to separate coleoid reproduction using other terms:<ref name="Strat">{{Cite journal | last1 = Rocha | first1 = F. | last2 = Guerra | first2 = Á. | last3 = González | first3 = Á. F. | doi = 10.1017/S1464793101005681 | title = A review of reproductive strategies in cephalopods | journal = Biological Reviews of the Cambridge Philosophical Society | volume = 76 | issue = 3 | pages = 291–304 | year = 2001 | pmid = 11569786| s2cid = 5777682 }}</ref>
1. One-time reproduction (formerly semelparity); being the occurrence of "simultaneous terminal spawning" (<!--simultaneous: animals gather together, -->terminal: occurring at the end of life). This group is characterized by synchronous ovulation (the ova all ripen prior to spawning), single-cycle spawning, and the absence of growth between egg batches.
2. Multiple reproductive events (formerly iteroparity). This category is divided further into:
* (i) polycyclic spawning; where single egg batches/clutches develop and are laid multiple times during the spawning season, with growth occurring between production of egg batches and breeding seasons and the gonads regenerate/ripen between clutches, e.g. ''Nautilus'' ;
* (ii) multiple spawning; where multiple clutches of eggs develop simultaneously, which can be differentiated in the ovaries through their development stage (also known as ''group-synchronous ovulation''). This method is defined by monocyclic spawning and the mother's growth between egg batches, e.g. ''Octopus chierchiae'', ''Sthenoteuthis oualaniensis'', ''Ommastrephes bartramii'', and ''Dosidicus gigas'' ;
* (iii) intermittent terminal spawning; with group-synchronous ovulation, monocyclic spawning, but the mother does not somatically grow between egg batches, e.g. ''Loligo vulgaris subspp.'', ''Loligo bleekeri'', ''Loligo forbesii'', ''Illex coindetii'', ''Todaropsis eblanae'', ''Todarodes angolensis'', and most populations of ''Sepia officinalis'' ;
* (iv) continuous spawning; where egg cells developed without any apparent "batches", with all stages of development potentially being present (or ''asynchronous ovulation''), monocyclic spawning and growth between egg batches, e.g. ''Cirrothauma murrayi'', ''Opisthoteuthis agassizii'', ''Opisthoteuthis grimaldii'' and ''Grimpoteuthis glacialis'', likely also includes ''Argonauta bottgeri'', ''Argonauta hians'', and ''Idiosepius pygmaeus''.
===Paralarva=== ''Paralarvae'' ({{singular}}: ''paralarva'') are young cephalopods immediately after hatching, prior to the development of adult diagnostic features and before exhibiting a similar ecology to older members of the same species. The term was introduced by Richard E. Young and Robert F. Harman in 1988; the term "larva" had been used previously, but it fell out of use as the term implied a metamorphosis occurred where larval body parts are lost completely and adult body parts developed from some "rudiments" left in an embryonic state; in contrast, young cephalopods do not undergo metamorphosis, they mostly grow morphometrically, though as this process still transforms the animal significantly, being comparable to the development of fish young (referred to as larva), the term "paralarva" (''para'': near, almost; near-larva/almost larva) was thus coined.<ref name="Young">{{cite journal|author=Richard Edward Young & Robert F. Harman|year=1988|title="Larva", "Paralarva", and "Subadult" in Cephalopod Terminology|journal=Malacologia|volume=29|issue=1|pages=201–207|url=https://www.biodiversitylibrary.org/page/25208582|access-date=August 13, 2011 }}</ref><ref name="YoungAlt">{{cite web |last1=Young |first1=R. |last2=Harman |first2=R. |title="Larva,""paralarva" and "subadult" in cephalopod terminology |url=https://www.semanticscholar.org/paper/%22Larva,%22%22paralarva%22-and-%22subadult%22-in-cephalopod-Young-Harman/7919dede1370b30468c10c644ff7f6e052f2c0a6 |website=semanticscholar.org |date=1988 |s2cid=86032555 |access-date=6 April 2025}}</ref><ref name="Ident">{{cite book |last1=Zaragoza |first1=N. |last2=Quetglas |first2=A. |last3=Moreno |first3=A. |last4=Anderson |first4=Emory D. |title=Identification guide for cephalopod paralarvae from the Mediterranean Sea |publisher=ICES Cooperative Research Report |location=Copenhagen |date=2015 |volume=324 |url=https://digital.csic.es/bitstream/10261/323583/4/Zaragoza%20et%20al%202015b.pdf |isbn=978-87-7482-156-4 |issn=1017-6195|access-date=6 April 2025}}</ref>
Paralarvae have been observed only in members of the Octopoda and Teuthida (which constitutes the modern definition of Coleoidea).<ref name="Young"/><ref>{{cite book |last1=Fernández-Gago |first1=Raquel |last2=Molist |first2=Pilar |last3=Anadón |first3=Ramón |chapter=Tissues of Paralarvae and Juvenile Cephalopods |title=Handbook of Pathogens and Diseases in Cephalopods |journal=Handbook of Diseases and Pathogens in Cephalopods |date=March 2019 |pages=87–109 |doi=10.1007/978-3-030-11330-8_5 |isbn=978-3-030-11329-2 |chapter-url=https://link.springer.com/chapter/10.1007/978-3-030-11330-8_5 |access-date=6 April 2025|chapter-url-access=subscription }}</ref> In the "iteroparous" species, the hatching of the paralarvae often heralds the death of the brooding mother.<ref name="Strat"/> Paralarvae may be planktonic, or they may remain on the bottom (demersal zone). Planktonic paralarvae remain so for a time, feeding on small food items (such as detritus) until they start their transition into their adult habitat and niche;<ref>{{cite journal |last1=Fernández-Álvarez |first1=Fernando Á |last2=Machordom |first2=Annie |last3=García-Jiménez |first3=Ricardo |last4=Salinas-Zavala |first4=César A |last5=Villanueva |first5=Roger |title=Predatory flying squids are detritivores during their early planktonic life |journal=Sci Rep |date=February 21, 2018 |volume=8 |issue=1 |page=3440 |doi=10.1038/s41598-018-21501-y |pmid=29467371 |pmc=5821876 |bibcode=2018NatSR...8.3440F }}</ref> a young coleoid is termed a subadult when it displays the features diagnostic for species identification in the adult, without having to display size- or sex-specific features. An adult is thus an animal showing the diagnostic traits of its species, along with signs of sexual maturity.<ref name="Young"/><ref name="Ontogeny">{{cite journal |last1=Vidal |first1=Erica A. G. |last2=Shea |first2=Elizabeth K. |title=Cephalopod ontogeny and life cycle patterns |journal=Frontiers in Marine Science |date=July 2023 |volume=10 |article-number=1162735 |doi=10.3389/fmars.2023.1162735 |doi-access=free |bibcode=2023FrMaS..1062735V |url=https://www.researchgate.net/publication/372211459 |access-date=6 April 2025}}</ref>
<gallery class="center" mode="nolines" widths="250" noborder="no" caption="Examples of paralarval cephalopods"> File:Psychroteuthis glacialis paralarva2.jpg|''Psychroteuthis glacialis'' File:Taningia_persica.jpg|''Taningia sp.'' File:Fish3566 - Flickr - NOAA Photo Library.jpg|Octopus paralarva File:Grimalditeuthis bonplandi paralarva (ROTATED).jpg|''Grimalditeuthis bonplandi'' </gallery> [[Image:Chtenopteryx sicula paralarvae.jpg|thumb|center|490px|''Chtenopteryx sicula'' paralarvae. '''Left:''' Two very young paralarvae. The circular tentacular clubs bear approximately 20 irregularly arranged suckers. Two chromatophores are present on each side of the mantle. '''Centre:''' Ventral, dorsal and side views of a more advanced paralarva. An equatorial circulet of seven large yellow-brown chromatophores is present on the mantle. Posteriorly the expanded vanes of the gladius are visible in the dorsal view. '''Right:''' Ventral and dorsal views of a very advanced paralarva.]]
==References== {{reflist}}
==External links== * {{CephBase Subclass |Coleoidea}} * [http://tolweb.org/tree?group=Coleoidea Tree of Life web project: Coleoidea] * [https://www.theatlantic.com/science/archive/2017/04/octopuses-do-something-really-strange-to-their-genes/522024/ "Octopuses Do Something Really Strange to Their Genes"]
{{Taxonbar |from=Q749814|from2=Q6560212}}
Category:Coleoidea Category:Neocoleoidea Category:Mollusc subclasses Category:Carboniferous first appearances Category:Neocephalopoda