{{Short description|Species of octopus}} {{Speciesbox | image = Octopus conispadiceus.JPG | image_alt = A specimen of Octopus conispadiceus preserved in a glass jar. | status = LC | status_system = IUCN3.1 | status_ref = <ref>{{cite iucn |author=Allcock, L. |author2=Taite, M. |author3=Allen, G. |year=2018 |title=''Chestnut Octopus'' |volume=2018 |article-number=e.T163397A1004745 |doi=10.2305/IUCN.UK.2018-2.RLTS.T163397A1004745.en |access-date=12 September 2025}}</ref> | genus = Octopus | species = conispadiceus | authority = Sasaki, 1917 }} '''''Octopus conispadiceus''''' (commonly the '''chestnut octopus'''<ref>{{Cite web |date=2018-06-04 |title=Order No. 229 of the Ministry of Agriculture establishing fisheries restrictions related to some species of aquatic biological resources for the period of 2018. |url=https://leap.unep.org/countries/ru/national-legislation/order-no-229-ministry-agriculture-establishing-fisheries |access-date=2023-01-20 |website=UNEP Law and Environment Assistance Platform |publisher=UN Environment Program}}</ref>) is a species of long-ligula<ref>{{Cite book |last=Rigby |first=Patricia Robin |title=Ecology of immature octopus Enteroctopus dofleini: Growth, movement and behaviour |date=2004-01-09 |oclc=1225501710}}</ref> octopus,<ref name=":0">{{Cite book |last1=Norman |first1=M. D. |url=https://books.google.com/books?id=f_F5DwAAQBAJ |title=Cephalopods of the World: An Annotated and Illustrated Catalogue of Cephalopod Species Known to Date |last2=Finn |first2=J. K. |publisher=Food and Agriculture Organization of the United Nations |year=2016 |isbn=978-92-5-107989-8 |editor-last=Jereb |editor-first=Patrizia |volume=3. Octopods and Vampire Squids |location=Rome, Italy |language=en |chapter=Family Octopodidae |editor-last2=Roper |editor-first2=Clyde F. E. |editor-last3=Norman |editor-first3=Mark D. |editor-last4=Finn |editor-first4=Julian K.}}</ref> provisionally placed in the genus ''Octopus''.<ref>{{Cite journal |last1=Norman |first1=M. D. |last2=Nabhitabhata |first2=J. |last3=Lu |first3=C. C. |date=2016-06-29 |title=An updated checklist of the cephalopods of the South China Sea |url=http://zoobank.org/urn:lsid:zoobank.org:pub:545C3882-6A19-4B1E-9114-9E4745AB2B75 |journal=Raffles Bulletin of Zoology |issue=Supplement 34 |pages=566–92}}</ref> It was first described by Madoka Sasaki in 1917<ref name=":1">{{Cite journal |date=1998 |editor-last=Voss |editor-first=Nancy A. |editor2-last=Vecchione |editor2-first=Michael |editor3-last=Toll |editor3-first=Ronald B. |editor4-last=Sweeney |editor4-first=Michael J. |title=Systematics and Biogeography of Cephalopods: Volume II |journal=Smithsonian Contributions to Zoology |issue=586 |pages=277–599 |doi=10.5479/si.00810282.586.277 |issn=0081-0282}}</ref> based on specimens bought at a fish market in Sapporo, Japan.<ref>{{Cite journal |last=Sasaki |first=Madoka |date=1915-07-27 |title=Notes on Cephalopoda |url=https://www.biodiversitylibrary.org/page/44265550#page/5/mode/1up |journal=Annotationes Zoologicae Japonenses |volume=9 |issue=1 |pages=361–7 |via=Biodiversity Heritage Library}}</ref>
== Description == ''O. conispadiceus'' is large,<ref name=":1" /> with a mantle length of up to 210 millimeters and a total length of at least 120 centimeters; its arms are moderate in length, around three times the length of the mantle.<ref name=":0" /> There are 140 to 150 suckers on each arm in males and 170 to 190 in females, and suckers are larger in males than females. ''O. conispadiceus'' is firm and muscular,<ref name=":1" /> with smooth skin,<ref name=":0" /> and light gray-blue in color<ref name=":1" /> with a white line across its head. It has seven rows of teeth and an ink sac.<ref name=":0" /> ''O. conispadiceus'' has small eyes.<ref name=":2">{{Cite journal |last=Sasaki |first=Madoka |date=1929-01-31 |title=A Monograph of the Dibranchiate Cephalopods of the Japanese and Adjacent Waters |url=https://eprints.lib.hokudai.ac.jp/dspace/handle/2115/12617 |journal=Journal of the Faculty of Agriculture, Hokkaido Imperial University |volume=20 |issue=Supplement |pages=1–397}}</ref>
== Distribution == ''O. conispadiceus'' is found in cold temperate waters<ref>{{Cite journal |last=Gleadall |first=Ian G. |date=2004 |title=Some Old and New Genera of Octopus |journal=Interdisciplinary Information Sciences |volume=10 |issue=2 |pages=99–112 |doi=10.4036/iis.2004.99 |issn=1347-6157|doi-access=free }}</ref> off northern Japan<ref name=":1" /> and the Kuril Islands.<ref name=":0" /><ref name=":3">{{Cite journal |last1=Ma |first1=Yuanyuan |last2=Zheng |first2=Xiaodong |last3=Cheng |first3=Rubin |last4=Li |first4=Qi |date=2014-06-27 |title=The complete mitochondrial genome of ''Octopus conispadiceus'' (Sasaki, 1917) (Cephalopoda: Octopodidae) |journal=Mitochondrial DNA |volume=27 |issue=2 |pages=1058–1059 |doi=10.3109/19401736.2014.928866 |issn=1940-1736 |pmid=24971549 |s2cid=39849240}}</ref> It is a benthic shelf species, living from depths of around 50 to 100 meters,<ref name=":0" /> mostly in sandy or muddy substrates.<ref name=":3" />
== Life cycle == ''O. conispadiceus'' reaches maturity quickly,<ref name=":3" /> around 10 to 11 months in cold waters.<ref>{{Cite journal |last=Boletzky |first=S. V. |date=1994 |title=Embryonic development of cephalopods at low temperatures |journal=Antarctic Science |volume=6 |issue=2 |pages=139–142 |doi=10.1017/s0954102094000210 |issn=0954-1020 |s2cid=84124491}}</ref> Juveniles look much like adults, but have a different skin texture.<ref name=":2" /> The species has a short life span, with estimates between under two years<ref name=":3" /> and three to four years.<ref name=":0" /> Females lay from 400<ref name=":4">{{Cite journal |last1=Sweeney |first1=Michael J. |last2=Roper |first2=Clyde F. E. |last3=Mangold |first3=Katharina M. |last4=Clark |first4=Malcolm R. |last5=Boletzky |first5=Sigurd V. |date=1992-02-10 |title="Larval" and juvenile cephalopods: a manual for their identification |journal=Smithsonian Contributions to Zoology |issue=513 |pages=1–182 |doi=10.5479/si.00810282.513 |issn=0081-0282}}</ref> up to 1,200 eggs at a time;<ref name=":0" /> the eggs are very large,<ref name=":4" /> up to 28 millimeters.<ref name=":1" /> The size of the eggs suggests that hatchlings are benthic.<ref name=":0" /><ref name=":4" />
== Use by humans == ''O. conispadiceus'' is fished commercially in Japan.<ref>{{Cite book |last=Kubodera |first=Tsunemi |url=https://www.kahaku.go.jp/research/publication/monograph/download/39/p385-404.pdf |title=Deep-sea Fauna and Pollutants off Pacific Coast of Northern Japan |publisher=National Museum of Nature and Science Monographs |year=2009 |editor-last=Fujita |editor-first=T. |location=Tokyo, Japan |pages=385–404 |language=en |chapter=A Review of the Deep-sea Cephalopod Fauna off the Pacific Coast of Northeastern Japan}}</ref><ref name=":0" /> It is the second most common species of octopus in fish markets in Hokkaido,<ref name=":3" /> and is sometimes bycatch in gillnet fishing, especially in Russia<ref>{{Cite journal |last1=Maeda |first1=Saki |last2=Sakurai |first2=Kenji |last3=Akamatsu |first3=Tomonari |last4=Matsuda |first4=Ayaka |last5=Yamamura |first5=Orio |last6=Kobayashi |first6=Mari |last7=Matsuishi |first7=Takashi Fritz |date=2021-02-11 |title=Foraging activity of harbour porpoises around a bottom-gillnet in a coastal fishing ground, under the risk of bycatch |journal=PLoS ONE |volume=16 |issue=2 |article-number=e0246838 |doi=10.1371/journal.pone.0246838 |pmid=33571306 |pmc=7877735 |issn=1932-6203|doi-access=free }}</ref><ref>{{Cite journal |last1=Besednova |first1=N. N. |last2=Zaporozhets |first2=T. S. |last3=Kovalev |first3=N. N. |last4=Makarenkova |first4=I. D. |last5=Yakovlev |first5=Yu. M. |date=2017-03-01 |title=Cephalopods: The potential for their use in medicine |journal=Russian Journal of Marine Biology |language=en |volume=43 |issue=2 |pages=101–110 |doi=10.1134/S1063074017020031 |s2cid=255014727 |issn=1608-3377}}</ref>
== References == {{Reflist}}
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Category:Cephalopods described in 1917 Category:Octopodidae
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