{{Short description|Measure of cognitive ability of cephalopods}} thumb|upright=1.5|An octopus, with around 500 million neurons<ref name=":1" />
'''Cephalopod intelligence''' is a measure of the cognitive ability of the cephalopod class of molluscs.
Intelligence is generally defined as the process of acquiring, storing, retrieving, combining, and comparing information and skills.<ref>{{Cite journal|last1=Humphreys|first1=Lloyd G.|author-link=Lloyd Humphreys|date=April–June 1979|title=The construct of general intelligence|url=https://www.beteronderwijsnederland.nl/files/construct%20of%20G%20Humphreys%201979.pdf|url-status=live|journal=Intelligence|type=editorial|volume=3|issue=2|pages=105–120|doi=10.1016/0160-2896(79)90009-6|issn=0160-2896|archive-url=https://web.archive.org/web/20170812230808/https://www.beteronderwijsnederland.nl/files/construct%20of%20G%20Humphreys%201979.pdf|archive-date=12 August 2017|access-date=13 December 2020}}</ref> Though these criteria are difficult to measure in nonhuman animals, cephalopods are the most intelligent invertebrates. The study of cephalopod intelligence also has an important comparative aspect in the broader understanding of animal cognition because it relies on a nervous system that is fundamentally different from that of vertebrates.<ref>[http://www.daviddarling.info/encyclopedia/C/cephalopodintel.html "Cephalopod intelligence"] {{Webarchive|url=https://web.archive.org/web/20200321104115/https://www.daviddarling.info/encyclopedia/C/cephalopodintel.html |date=2020-03-21 }} in The Encyclopedia of Astrobiology, Astronomy, and Spaceflight.</ref> In particular, the Coleoidea subclass (cuttlefish, squid, and octopuses) is thought to contain the most intelligent invertebrates. It is also thought to be an important example of advanced cognitive evolution in animals, though nautilus intelligence is also a subject of growing interest among zoologists.<ref name="crook">{{cite journal|last1=Crook|first1=Robyn|last2=Basil|first2=Jennifer|year=2008|title=A biphasic memory curve in the chambered nautilus, ''Nautilus pompilius'' L. (Cephalopoda: Nautiloidea)|url=https://jeb.biologists.org/content/jexbio/211/12/1992.full.pdf|url-status=live|journal=Journal of Experimental Biology|volume=211|issue=12|pages=1992–1998|doi=10.1242/jeb.018531|pmid=18515730|archive-url=https://web.archive.org/web/20181104170130/https://jeb.biologists.org/content/jexbio/211/12/1992.full.pdf|archive-date=4 November 2018|access-date=13 December 2020|doi-access=free|bibcode=2008JExpB.211.1992C |name-list-style=amp}}</ref>
The scope of cephalopod intelligence and learning capability is controversial within the biological community, complicated by the inherent complexity of quantifying non-vertebrate intelligence. In spite of this, the existence of impressive spatial learning capacity, navigational abilities, and predatory techniques in cephalopods is widely acknowledged.<ref>{{cite news|last=Hunt|first=Elle|date=28 March 2017|title=Alien intelligence: the extraordinary minds of octopuses and other cephalopods|work=The Guardian|url=https://www.theguardian.com/environment/2017/mar/28/alien-intelligence-the-extraordinary-minds-of-octopuses-and-other-cephalopods|url-status=live|archive-url=https://web.archive.org/web/20200418101916/https://www.theguardian.com/environment/2017/mar/28/alien-intelligence-the-extraordinary-minds-of-octopuses-and-other-cephalopods|archive-date=18 April 2020}}</ref><ref>{{Cite news|last=Bilefsky|first=Dan|date=April 13, 2016|title=Inky the Octopus Escapes From a New Zealand Aquarium|work=The New York Times|url=https://www.nytimes.com/2016/04/14/world/asia/inky-octopus-new-zealand-aquarium.html|url-status=live|url-access=limited|access-date=24 April 2016|archive-url=https://web.archive.org/web/20200416193614/https://www.nytimes.com/2016/04/14/world/asia/inky-octopus-new-zealand-aquarium.html|archive-date=16 April 2020}}</ref> Cephalopods are legally classified as being at least as sentient as vertebrates in some countries<ref name=AW2022>{{cite web|url=http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:276:0033:0079:EN:PDF|title=DIRECTIVE 2010/63/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL|publisher=Official Journal of the European Union|at=Article 1, 3(b)|access-date=18 February 2015}}</ref> and have been compared to intelligent extraterrestrials, due to their convergently evolved mammal-like intelligence.<ref>{{cite web |last=Baer |first=Drake |date=20 December 2016 |title=Octopuses Are 'the Closest We Will Come to Meeting an Intelligent Alien' |publisher=Science of Us |access-date=26 April 2017 |url=http://nymag.com/scienceofus/2016/12/octopuses-are-intelligent-aliens.html}}</ref>
== Brain size and structure == Cephalopods have large, well-developed brains,<ref>{{cite book|last1=Tricarico|first1=Elena|title=Biocommunication of Animals|last2=Amodio|first2=Piero|last3=Ponte|first3=Giovanna|last4=Fiorito|first4=Graziano|publisher=Springer|year=2014|isbn=978-94-007-7413-1|editor-last=Witzany|editor-first=Guenther|pages=337–349|chapter=Cognition and recognition in the cephalopod mollusc ''Octopus vulgaris'': coordinating interaction with environment and conspecifics|doi=10.1007/978-94-007-7414-8_19|lccn=2019748877}}</ref><ref>{{Cite journal|last1=Chung|first1=Wen-Sung|last2=Kurniawan|first2=Nyoman D.|last3=Marshall|first3=N. Justin|date=2020|title=Toward an MRI-Based Mesoscale Connectome of the Squid Brain|journal=iScience|volume=23|issue=1|article-number=100816|doi=10.1016/j.isci.2019.100816|issn=2589-0042|pmc=6974791|pmid=31972515|bibcode=2020iSci...23j0816C|doi-access=free}}</ref><ref name=":0">{{Cite journal|last1=Chung|first1=Wen-Sung|last2=Kurniawan|first2=Nyoman D.|last3=Marshall|first3=N. Justin|date=2021-11-18|title=Comparative brain structure and visual processing in octopus from different habitats|journal=Current Biology|volume=32|issue=1 |pages=97–110.e4|language=English|doi=10.1016/j.cub.2021.10.070|issn=0960-9822|pmid=34798049|s2cid=244398601|doi-access=free}}</ref> and their brain-to-body mass ratio is among the largest of all invertebrates, falling between that of endothermic and ectothermic vertebrates.<ref name=":0" /><ref>{{Cite book|last=Budelmann|first=B. U.|title=The nervous systems of invertebrates: An evolutionary and comparative approach|publisher=Birkhäuser|year=1995|isbn=978-3-7643-5076-5|editor1-last=Breidbach|editor1-first=O.|chapter=The cephalopod nervous system: What evolution has made of the molluscan design|lccn=94035125|editor2-last=Kutsch|editor2-first=W.|chapter-url=https://books.google.com/books?id=dW5e6FHOH-4C&pg=PA115}}</ref><ref name="Cephalopods2">{{cite book|title=The Brains and Lives of Cephalopods|last1=Nixon|first1=Marion|last2=Young|first2=John Z.|date=4 September 2003|publisher=Oxford University Press|isbn=978-0-19-852761-9|lccn=2002041659|publication-date=November 6, 2003|author-link2=John Zachary Young}}</ref> The large nerve fibers of the cephalopod mantle have been widely used for many years as experimental material in neurophysiology; their large diameter (due to lack of a myelin sheath) makes them relatively easy to study compared with other animals.<ref>{{Cite journal|last1=Tasaki|first1=I.|last2=Takenaka|first2=T.|date=October 1963|title=Resting and action potential of squid giant axons intracellularly perfused with sodium-rich solutions|url=https://www.pnas.org/content/pnas/50/4/619.full.pdf|url-status=live|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=50|issue=4|pages=619–626|bibcode=1963PNAS...50..619T|doi=10.1073/pnas.50.4.619|pmc=221236|pmid=14077488|archive-url=https://web.archive.org/web/20180811010907/https://www.pnas.org/content/pnas/50/4/619.full.pdf|archive-date=11 August 2018|access-date=13 December 2020|doi-access=free}}</ref> Unlike vertebrates, octopus arms have their own neurons, so they do not require input from their central brain to function.<ref name=":1">{{Cite journal |last=Carls-Diamante |first=Sidney |date=2022-03-14 |title=Where Is It Like to Be an Octopus? |journal=Frontiers in Systems Neuroscience |language=en |volume=16 |doi=10.3389/fnsys.2022.840022 |doi-access=free |pmid=35401127 |pmc=8988249 }}</ref> In fact, two-thirds of an octopus's neurons are in the nerve cords of its arms. These are capable of complex reflex actions without input from the brain.<ref>{{Cite journal |last1=Yekutieli |first1=Yoram |last2=Sagiv-Zohar |first2=Roni |last3=Aharonov |first3=Ranit |last4=Engel |first4=Yaakov |last5=Hochner |first5=Binyamin |last6=Flash |first6=Tamar |date=August 2005 |title=Dynamic Model of the Octopus Arm. I. Biomechanics of the Octopus Reaching Movement |url=https://www.physiology.org/doi/10.1152/jn.00684.2004 |journal=Journal of Neurophysiology |language=en |volume=94 |issue=2 |pages=1443–1458 |doi=10.1152/jn.00684.2004 |pmid=15829594 |issn=0022-3077|url-access=subscription }}</ref>
== Behavior ==
=== Predation === [[File:Veined_Octopus_-_Amphioctopus_Marginatus_eating_a_Crab.jpg|thumb|A veined octopus eating a crab]] Unlike most other molluscs, all cephalopods are active predators (with the possible exceptions of the Bigfin squid and vampire squid). Their need to locate and capture their prey has likely been the driving force behind the development of their intelligence.<ref>{{Cite journal|last1=Villanueva|first1=Roger|last2=Perricone|first2=Valentina|last3=Fiorito|first3=Graziano|date=2017-08-17|title=Cephalopods as Predators: A Short Journey among Behavioral Flexibilities, Adaptions, and Feeding Habits|journal=Frontiers in Physiology|volume=8|page=598|doi=10.3389/fphys.2017.00598|issn=1664-042X|pmc=5563153|pmid=28861006|doi-access=free}}</ref>
Crabs, the favorite food source of most octopus species, present significant challenges with their powerful pincers and their potential to exhaust the cephalopod's respiration system from a prolonged pursuit. Because of these challenges, octopuses will sometimes seek out lobster traps and steal the bait inside. They are also known to climb aboard fishing boats and hide in the containers that hold dead or dying crabs.<ref>Cousteau, Jacques Yves (1978). Octopus and Squid: The Soft Intelligence</ref><ref name="denizen">{{cite web|url=http://nationalzoo.si.edu/Support/AdoptSpecies/AnimalInfo/GiantOctopus/default.cfm|title=Giant Octopus – Mighty but Secretive Denizen of the Deep|date=2 January 2008|publisher=Smithsonian National Zoological Park|archive-url=https://web.archive.org/web/20120825030432/http://nationalzoo.si.edu/Support/AdoptSpecies/AnimalInfo/GiantOctopus/default.cfm|archive-date=25 August 2012|access-date=4 February 2014}}</ref>
Captive octopuses have also been known to climb out of their tanks, travel some distance, enter another aquarium to feed, and return to their own aquariums.<ref name="Wood Anderson2">{{cite journal|last1=Wood|first1=J. B|last2=Anderson|first2=R. C|date=2004|title=Interspecific Evaluation of Octopus Escape Behavior|url=http://www.thecephalopodpage.org/_pdf/2004Escape.pdf|journal=Journal of Applied Animal Welfare Science|volume=7|pages=95–106|doi=10.1207/s15327604jaws0702_2|pmid=15234886|access-date=11 September 2015|number=2|s2cid=16639444}}</ref><ref>{{cite book|chapter-url={{google books | plainurl=y | id=lD8DAAAAQAAJ | page=38}}|title=Aquarium Notes – The Octopus; or, the "devil-fish" of fiction and of fact|last=Lee|first=Henry|date=1875|publisher=Chapman and Hall|location=London|pages=38–39|chapter=V: The octopus out of water|oclc=1544491|quote=The marauding rascal had occasionally issued from the water in his tank, and clambered up the rocks, and over the wall into the next one; there he had helped himself to a young lump-fish, and, having devoured it, returned demurely to his own quarters by the same route, with well-filled stomach and contented mind.|access-date=11 September 2015}}</ref><ref>{{Cite news|url=https://www.theguardian.com/world/2016/apr/13/the-great-escape-inky-the-octopus-legs-it-to-freedom-from-new-zealand-aquarium?CMP=Share_iOSApp_Other|title=The great escape: Inky the octopus legs it to freedom from aquarium|last=Roy|first=Eleanor Ainge|date=14 April 2016|work=The Guardian (Australia)}}</ref>
=== Communication === [[File:Camouflage cuttlefish 02.jpg|thumb|A cuttlefish employing camouflage in its natural habitat]]Although believed{{By whom|date=April 2025}} to not be the most social of animals, some{{Which|date=April 2025}} cephalopods are highly social creatures. When isolated from their own kind, some species have been observed shoaling with fish.<ref name="Packard1972">{{cite journal |last1=Packard |first1=A. |year=1972 |title=Cephalopods and fish: The limits of convergence |journal=Biological Reviews |volume=47 |issue=2 |pages=241–307 |doi=10.1111/j.1469-185X.1972.tb00975.x |s2cid=85088231}}</ref>
Cephalopods are able to communicate visually using a diverse range of signals. To produce these signals, cephalopods can use four types of communication elements: chromatic (skin coloration), skin texture (e.g. rough or smooth), posture, and locomotion.<ref name="pays2">{{cite journal |last1=Brown |first1=C. |last2=Garwood |first2=M. P. |last3=Williamson |first3=J.E. |year=2012 |title=It pays to cheat: Tactical deception in a cephalopod social signalling system |journal=Biology Letters |volume=8 |issue=5 |pages=729–732 |doi=10.1098/rsbl.2012.0435 |pmc=3440998 |pmid=22764112}}</ref> Some cephalopods are capable of rapid changes in skin colour and pattern using chromatophores, iridophores, and leucophores.<ref name="cephalopod12">{{cite journal |last1=Cloney |first1=R.A. |last2=Florey |first2=E. |year=1968 |title=Ultrastructure of cephalopod chromatophore organs |journal=Z. Zellforsch. Mikrosk. Anat. |volume=89 |issue=2 |pages=250–280 |doi=10.1007/BF00347297 |pmid=5700268|s2cid=26566732 }}</ref> This ability almost certainly evolved for camouflage. However, some squid and cuttlefish use flashing colors and patterns to communicate with each other in various courtship rituals.<ref name="pays2" /> Caribbean reef squid can even discriminate between recipients, sending one message using color patterns to a squid on their right, while they send another message to a squid on their left.<ref name="wood2">{{cite web |url=http://www.thecephalopodpage.org/Ssepioidea.php |title=''Sepioteuthis sepioidea'', Caribbean Reef squid |publisher=The Cephalopod Page |access-date=2010-01-20 |df=dmy-all}}</ref><ref name="Byrne2">{{cite journal |author1=Byrne, R.A. |author2=Griebel, U. |author3=Wood, J.B. |author4=Mather, J.A. |year=2003 |title=Squids say it with skin: A graphic model for skin displays in Caribbean Reef Squid |journal=Berliner Geowissenschaftliche Abhandlungen |volume=3 |pages=29–35}}</ref> Tests show that octopuses become more sociable when exposed to the psychoactive drug MDMA.<ref>{{cite news |last1=Nuwer |first1=Rachel |author-link=Rachel Nuwer |title=Rolling under the Sea: Scientists Gave Octopuses Ecstasy to Study Social Behavior |url=https://www.scientificamerican.com/article/rolling-under-the-sea-scientists-gave-octopuses-ecstasy-to-study-social-behavior/ |work=Scientific American |language=en}}</ref>
The Humboldt squid shows high amounts of cooperation and communication in its hunting techniques. This was one of the first observations of cooperative hunting in invertebrates.<ref name="zimmerman">{{cite magazine |title=Behold the Humboldt squid |first=Tim |last=Zimmermann |magazine=Outside Magazine |date=July 2006 |url=http://outside.away.com/outside/features/200607/sea-of-cortez-humboldt-squid-1.html}}</ref>
It is believed that squids are slightly less intelligent than octopuses and cuttlefish; however, various species of squid act more social than other octopuses and cuttlefish, leading some researchers to conclude that squids are on par with dogs in terms of intelligence.<ref>{{Cite web |date=2020-02-10 |title=Are squids as smart as dogs? |url=https://www.medicalnewstoday.com/articles/are-squids-as-smart-as-dogs |access-date=2021-06-07 |website=www.medicalnewstoday.com |language=en}}</ref>
=== Object manipulation === <gallery mode="packed" style="float:right " heights="190" caption="Octopus opening a container with a screw cap"> File:Oktopus opening a container with screw cap 01.jpg File:Oktopus opening a container with screw cap 02.jpg File:Oktopus opening a container with screw cap 03.jpg File:Oktopus opening a container with screw cap 04.jpg </gallery> The highly sensitive suction cups and prehensile arms of octopuses, squid, and cuttlefish allow them to hold and manipulate objects, including the use of tools. Octopuses can solve complex puzzles requiring pushing or pulling actions, and can also unscrew the lids of containers and open the latches on acrylic boxes in order to obtain the food inside. They can also remember solutions to puzzles and learn to solve the same puzzle presented in different configurations.<ref>{{Cite journal |last1=Richter |first1=Jonas N. |last2=Hochner |first2=Binyamin |last3=Kuba |first3=Michael J. |date=2016-03-22 |title=Pull or Push? Octopuses Solve a Puzzle Problem |journal=PLOS ONE |language=en |volume=11 |issue=3 |article-number=e0152048 |doi=10.1371/journal.pone.0152048 |pmid=27003439 |pmc=4803207 |issn=1932-6203 |bibcode=2016PLoSO..1152048R |doi-access=free}}</ref>
Smaller individuals of the Common blanket octopus (''Tremoctopus violaceus'') will hold the tentacles of the Portuguese man o' war (whose venom they are immune to), both as a means of protection and as a method of capturing prey.<ref>{{cite journal |last1=Jones |first1=Everet C. |date=22 February 1963 |title=''Tremoctopus violaceus'' uses ''Physalia'' tentacles as weapons |journal=Science |volume=139 |issue=3556 |pages=764–766 |bibcode=1963Sci...139..764J |doi=10.1126/science.139.3556.764 |jstor=1710225 |pmid=17829125 |s2cid=40186769}}</ref>
[[File:Octopus shell.jpg|thumb|right|A small veined octopus (4–5 cm in diameter) using a nut shell and clam shell as shelter]] At least four individuals of the Veined octopus (''Amphioctopus marginatus'') have been observed retrieving discarded coconut shells, transporting them some distance, and then reassembling them for use as a shelter.<ref>{{Cite journal|last1=Finn|first1=Julian K.|last2=Tregenza|first2=Tom|last3=Norman|first3=Mark D.|date=15 December 2009|title=Defensive tool use in a coconut-carrying octopus|url=https://sites.oxy.edu/clint/learn/articles/defensivetooluseinacoconutcarryingoctopus.pdf|url-status=live|journal=Current Biology|volume=19|issue=23|pages=R1069–R1070|doi=10.1016/j.cub.2009.10.052|pmid=20064403|archive-url=https://web.archive.org/web/20170811002225/https://sites.oxy.edu/clint/learn/articles/defensivetooluseinacoconutcarryingoctopus.pdf|archive-date=11 August 2017|via=Occidental College|doi-access=free|bibcode=2009CBio...19R1069F }}</ref> It is theorized that the octopuses used seashells for the same purpose before humans made coconut shells widely available on the sea floor.<ref>{{cite news|last=Morelle|first=Rebecca|author-link=Rebecca Morelle|date=14 December 2009|title=Octopus snatches coconut and runs|work=BBC News|url=https://news.bbc.co.uk/1/hi/sci/tech/8408233.stm|url-status=live|access-date=20 January 2010|archive-url=https://web.archive.org/web/20200531101841/http://news.bbc.co.uk/2/hi/science/nature/8408233.stm|archive-date=31 May 2020}}</ref><ref>{{cite web|url=http://www.edutube.org/video/coconut-shelter-evidence-tool-use-octopuses|title=Coconut shelter: evidence of tool use by octopuses | EduTube Educational Videos|date=2009-12-14|publisher=Edutube.org|archive-url=https://web.archive.org/web/20131024173037/http://edutube.org/video/coconut-shelter-evidence-tool-use-octopuses|archive-date=2013-10-24|access-date=2010-01-20}}</ref> Other sea creatures construct homes in a similar manner; for example, most hermit crabs use the discarded shells of other species for habitation, and some crabs place sea anemones on their carapaces for protection and camouflage. However, this behavior lacks some of the complexity of the octopus' behavior, which involves picking up and carrying a tool for later use. (This argument remains contested by a number of biologists, who claim that the shells actually provide protection from bottom-dwelling predators during transport.<ref>{{YouTube|id=hlh0cS2tf24|title=Octopus tool use}} published January 26, 2010 New Scientist</ref>)
Octopuses have also been known to deliberately place stones, shells, and even bits of broken bottles to form walls that constrict their den openings.<ref name="Map Of Life2">{{cite web |url=http://www.mapoflife.org/topics/topic_59_Simple-tool-use-in-owls-and-cephalopods/ |title=Simple tool use in owls and cephalopods |year=2010 |publisher=Map Of Life |access-date=July 23, 2013}}</ref> In laboratory studies, the Caribbean dwarf octopus (''Octopus mercatoris)'', a small pygmy species of octopus, has been observed to block its lair using plastic Lego bricks.<ref name="Oinuma">Oinuma, Colleen, (14 April 2008). "''Octopus mercatoris'' response behavior to novel objects in a laboratory setting: Evidence of play and tool use behavior?" In ''Octopus Tool Use and Play Behavior''[http://nature.berkeley.edu/classes/es196/projects/2008final/Oinuma_2008.pdf]</ref>
Cephalopods benefit from environmental enrichment, which indicates behavioral and neuronal flexibility not exhibited by most other invertebrates.<ref name="Mather2010">{{cite book |author=Mather, J.A., Anderson, R.C. and Wood, J.B. |title=Octopus: The Ocean's Intelligent Invertebrate |publisher=Timber Press |year=2010}}</ref> For example, captive octopuses require stimulation or they will become lethargic.<ref>{{Cite web|url=https://curiosity.com/topics/captive-octopuses-need-intellectual-stimulation-or-else-they-get-bored-curiosity/|archive-url=https://web.archive.org/web/20181119092029/https://curiosity.com/topics/captive-octopuses-need-intellectual-stimulation-or-else-they-get-bored-curiosity/|archive-date=November 19, 2018|title=Captive Octopuses Need Intellectual Stimulation Or Else They Get Bored|website=curiosity.com|access-date=2018-11-19}}</ref>
At the Sea Star Aquarium in Coburg, Germany, an octopus named Otto was known to juggle hermit crabs around, as well as strike the aquarium glass with a rock. On more than one occasion, Otto even caused a short circuit by shooting a jet of water at the overhead lamp.<ref>{{Cite news|date=31 October 2008|title=Otto the octopus wreaks havoc|work=The Telegraph|url=https://www.telegraph.co.uk/news/newstopics/howaboutthat/3328480/Otto-the-octopus-wrecks-havoc.html|url-status=live|url-access=subscription|archive-url=https://web.archive.org/web/20110624091024/https://www.telegraph.co.uk/news/newstopics/howaboutthat/3328480/Otto-the-octopus-wrecks-havoc.html|archive-date=24 June 2011}}</ref> Otto was even claimed to have developed a sense of personal taste as to the arrangement of his tank.<ref>https://evolutionnews.org/2022/08/octopus-intelligence-poses-evolutionary-convergence-conundrum/</ref>
=== Lethargy === It is suggested that octopus have a complex, vertebrate-like sleep pattern, with two separate stages similar to REM and NREM stages necessary for the cognitive functions of vertebrates. "Quiet sleep" stage usually involves behaviors such as eyes closing, flat body posture, and white-skin pattern. This stage usually lasts around 60 minutes. After the "quiet stage", the octopus moves onto an "active sleep" stage which lasts about 1 minute. In the "active sleep" stage, octopus has more eye and body movements as well as increased breathing rate. Although the octopus is suggested to have the most obvious color changing during the "active sleep" stage, a very brief and fast "color-flash" has been observed during the "quiet sleep" stage as well.<ref>{{Cite journal |last1=Pophale |first1=Aditi |last2=Shimizu |first2=Kazumichi |last3=Mano |first3=Tomoyuki |last4=Iglesias |first4=Teresa L. |last5=Martin |first5=Kerry |last6=Hiroi |first6=Makoto |last7=Asada |first7=Keishu |last8=Andaluz |first8=Paulette García |last9=Van Dinh |first9=Thi Thu |last10=Meshulam |first10=Leenoy |last11=Reiter |first11=Sam |date=2023-07-06 |title=Wake-like skin patterning and neural activity during octopus sleep |journal=Nature |language=en |volume=619 |issue=7968 |pages=129–134 |doi=10.1038/s41586-023-06203-4 |pmid=37380770 |issn=0028-0836|pmc=10322707 |bibcode=2023Natur.619..129P }}</ref>
== Learning == In laboratory experiments, octopuses can be readily trained to distinguish between different shapes and patterns.
In one study on observational learning, common octopuses (observers) were allowed to watch other octopuses (demonstrators) select one of two objects that differed only in color. Subsequently, the observers consistently selected the same object the demonstrators did. This study concluded that octopuses are capable of using observational learning.<ref>{{cite journal|last1=Fiorito|first1=Graziano|last2=Scotto|first2=Pietro|date=24 April 1992|title=Observational Learning in Octopus vulgaris|url=https://www.researchgate.net/publication/6052505|journal=Science|volume=256|issue=5056|pages=545–547|doi=10.1126/science.256.5056.545|pmid=17787951|access-date=18 February 2015|bibcode=1992Sci...256..545F|s2cid=29444311}}</ref> However, this is disputed by some.<ref>{{cite news|url=https://www.newscientist.com/article/mg15420854.100-what-is-this-octopus-thinking.html|title=What is this octopus thinking?|last1=Hamilton|first1=Garry|date=7 June 1997|work=New Scientist|access-date=18 February 2015|issue=2085|pages=30–35}}</ref> Both octopuses and nautiluses are capable of vertebrate-like spatial learning.<ref name="Crook and walters">{{cite journal|author1=Crook, R.J.|author2=Walters, E.T.|name-list-style=amp|year=2011|title=Nociceptive behavior and physiology of molluscs: animal welfare implications|journal=ILAR Journal|volume=52|issue=2|pages=185–195|doi=10.1093/ilar.52.2.185|pmid=21709311|doi-access=free}}</ref> Additionally, cuttlefish have been shown to have the capacity for future planning and reward processing after being tested with the Stanford marshmallow experiment.<ref>{{Cite web |last=Starr |first=Michelle |date=3 March 2021 |title=A Cephalopod Has Passed a Cognitive Test Designed For Human Children |url=https://www.sciencealert.com/cuttlefish-can-pass-a-cognitive-test-designed-for-children |access-date=2021-03-03 |website=ScienceAlert |language=en-gb}}</ref>
== Protective legislation == right|thumb|An octopus in a public aquarium Due to their intelligence, cephalopods are commonly protected by animal testing regulations that do not usually apply to invertebrates.
In the UK from 1993 to 2012, the common octopus (''Octopus vulgaris'') was the only invertebrate protected under the Animals (Scientific Procedures) Act 1986.<ref>{{cite web|url=http://www.legislation.gov.uk/uksi/1993/2103/article/3/made#text%3D%22Octopus%22|title=The Animals (Scientific Procedures) Act (Amendment) Order 1993|publisher=The National Archives|access-date=18 February 2015}}</ref> Since 2022, all vertebrates, cephalopods, and decapods have been recognised as sentient by the Animal Welfare (Sentience) Act 2022. Cephalopods are the only invertebrates protected under the 2010 European Union directive "on the protection of animals used for scientific purposes".<ref name=AW2022 /> Some scholars have argued for increased protections for cephalopods in the United States as well.<ref>{{cite journal|last1=Zabel|first1=Joseph|date=Spring 2019|title=Legislators Need to Develop a Backbone for Animals that Lack One: Including Cephalopods in the Animal Welfare Act|url=https://drive.google.com/file/d/1T1YAz5b48C5ukfVCKI--WQCt-7ejUkqK/view|journal=Journal of Animal and Environmental Law|publisher=University of Louisville School of Law|volume=10|issue=2|page=1}}</ref>
== See also ==
*Animal cognition *Animal consciousness *Octopolis and Octlantis
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== References == {{reflist}}
== Further reading ==
* [http://ocean.si.edu/blog/so-you-think-youre-smarter-cephalopod ''So you think you're smarter than a cephalopod?''] by Wendy Williams, At the Smithsonian's Ocean Portal. * [http://www.thecephalopodpage.org/behavior.php ''What behavior can we expect of octopuses?''] by Dr. Jennifer Mather, Department of Psychology and Neuroscience, University of Lethbridge and Roland C. Anderson, The Seattle Aquarium. * [http://www.nwf.org/News-and-Magazines/National-Wildlife/Animals/Archives/1997/Armed-But-Not-Dangerous.aspx ''Is the octopus really the invertebrate intellect of the sea?''] by Doug Stewart. In: National Wildlife. Feb/Mar 1997, vol.35 no.2. * [https://web.archive.org/web/20080102230427/http://nationalzoo.si.edu/Support/AdoptSpecies/AnimalInfo/GiantOctopus/default.cfm ''Giant Octopus – Mighty but Secretive Denizen of the Deep''] from the National Zoo in Washington D.C. * [https://www.sciencedaily.com/releases/2008/05/080531074905.htm ''Living Fossils Have Long- And Short-term Memory Despite Lacking Brain Structures Of Modern Cephalopods''] * {{Cite journal|last1=Shigeno|first1=Shuichi|last2=Andrews|first2=Paul L.R.|last3=Ponte|first3=Giovanna|last4=Fiorito|first4=Graziano|date=July 2018|title=Cephalopod Brains: An Overview of Current Knowledge to Facilitate Comparison With Vertebrates|journal=Frontiers in Physiology|volume=9|page=952|doi=10.3389/fphys.2018.00952|pmc=6062618|pmid=30079030|doi-access=free}} * [http://www.thecephalopodpage.org/smarts.php Octopuses are Smart Suckers!?] By Dr. Jennifer Mather, Department of Psychology and Neuroscience, University of Lethbridge and Roland C. Anderson, The Seattle Aquarium * {{Cite magazine|last1=Tzar|first1=Jennifer|last2=Scigliano|first2=Eric|date=January 19, 2003|title=Through the Eye of an Octopus|url=https://www.discovermagazine.com/planet-earth/through-the-eye-of-an-octopus|url-status=live|magazine=Discover|archive-url=https://web.archive.org/web/20200826120916/https://www.discovermagazine.com/planet-earth/through-the-eye-of-an-octopus|archive-date=August 26, 2020}} * [https://web.archive.org/web/20150208120700/http://intelligence.seti.org/pages/invertebrates The Diversity and Evolution of Invertebrate Nervous Systems] ''Set Institute''. Retrieved 12 December 2014. * {{Cite magazine|last=Godfrey-Smith|first=Peter|author-link=Peter Godfrey-Smith|date=January 1, 2017|title=The Mind of an Octopus|url=https://www.scientificamerican.com/article/the-mind-of-an-octopus/|url-status=live|magazine=Scientific American Mind|volume=28|issue=1|pages=62–69|doi=10.1038/scientificamericanmind0117-62|archive-url=https://web.archive.org/web/20200929133236/https://www.scientificamerican.com/article/the-mind-of-an-octopus/|archive-date=September 29, 2020}} * {{cite journal|last1=Hochner|first1=Binyamin|last2=Shomrat|first2=Tal|last3=Fiorito|first3=Graziano|date=June 1, 2006|title=The Octopus: A Model for a Comparative Analysis of the Evolution of Learning and Memory Mechanisms|journal=Biological Bulletin|volume=210|issue=3|pages=308–817|doi=10.2307/4134567|jstor=4134567|pmid=16801504|s2cid=15274048}} * {{cite book|title=Brain and Behaviour in Cephalopods|last=Wells|first=Martin John|publisher=Heinemann|year=1962|series=University biology monographs|lccn=62016373|id=NLM ID: 0053226}} * {{cite book|title=Cephalopod Behaviour|last2=Messenger|first2=John B.|last1=Hanlon|first1=Roger T.|publisher=Cambridge University Press|year=1996|isbn=978-0-521-42083-9|lccn=95010249}} * {{cite book|title=Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness|last=Godfrey-Smith|first=Peter|publisher=Farrar, Straus & Giroux|year=2016|isbn=978-0-374-22776-0|lccn=2016016696|author-link=Peter Godfrey-Smith}} {{animal cognition}}
Category:Animal intelligence Intelligence