Cephalopod intelligence#Tool use

Cephalopods have large, well-developed brains,{{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}}{{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|pages=100816|doi=10.1016/j.isci.2019.100816|issn=2589-0042|pmc=6974791|pmid=31972515|bibcode=2020iSci...23j0816C|doi-access=free}}{{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}} and their brain-to-body mass ratio is the largest among the invertebrates, falling between that of endothermic and ectothermic vertebrates.{{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}}{{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=978-0198527619|lccn=2002041659|publication-date=November 6, 2003|author-link2=John Zachary Young}} 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.{{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}} An octopus's nerves are not limited to the brain. 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.{{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 }}

File:Veined_Octopus_-_Amphioctopus_Marginatus_eating_a_Crab.jpg 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.{{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|pages=598|doi=10.3389/fphys.2017.00598|issn=1664-042X|pmc=5563153|pmid=28861006|doi-access=free}}

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.Cousteau, Jacques Yves (1978). Octopus and Squid: The Soft Intelligence{{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|url-status=dead|access-date=4 February 2014}}

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.{{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}}{{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}}{{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)}}

File:Camouflage cuttlefish 02.jpg 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.{{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}}

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.{{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}} Some cephalopods are capable of rapid changes in skin colour and pattern using chromatophores, iridophores, and leucophores.{{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 }} 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. 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.{{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}}{{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}} Tests show that octopuses become more sociable when exposed to the psychoactive drug MDMA.{{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}}

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.{{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}}

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.{{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}}

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.{{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}} However, this is disputed by some.{{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}} Both octopuses and nautiluses are capable of vertebrate-like spatial learning.{{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}} Additionally, cuttlefish have been shown to have the capacity for future planning and reward processing after being tested with the Stanford marshmallow experiment.{{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}}

File:Octopus shell.jpg (4–5 cm in diameter) using a nut shell and clam shell as shelter]]The octopus shows flexibility in the use of tools.

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.{{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 }} It is theorized that the octopuses used shells for the same purpose before humans made coconut shells widely available on the sea floor.{{cite news|last=Morelle|first=Rebecca|author-link=Rebecca Morelle|date=14 December 2009|title=Octopus snatches coconut and runs|work=BBC News|url=http://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}}{{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|url-status=dead|access-date=2010-01-20}} 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.{{YouTube|id=hlh0cS2tf24|title=Octopus tool use}} published January 26, 2010 New Scientist)

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.{{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}}

Octopuses have also been known to deliberately place stones, shells, and even bits of broken bottles to form walls that constrict their den openings.{{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}} 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.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]

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

The highly sensitive suction cups and prehensile arms of octopuses, squid, and cuttlefish allow them to hold and manipulate objects. However, unlike vertebrates, octopus arms have their own neurons, so they do not require input from their central brain to function.{{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 }}

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.{{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 |pages=e0152048 |doi=10.1371/journal.pone.0152048 |pmid=27003439 |pmc=4803207 |issn=1932-6203 |bibcode=2016PLoSO..1152048R |doi-access=free}}

Cephalopods benefit from environmental enrichment, which indicates behavioral and neuronal flexibility not exhibited by most other invertebrates.{{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}} For example, captive octopuses require stimulation or they will become lethargic.{{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/|url-status=dead|archive-date=November 19, 2018|title=Captive Octopuses Need Intellectual Stimulation Or Else They Get Bored|website=curiosity.com|access-date=2018-11-19}}

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.{{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}}

File:Octopus.jpg

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.{{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}} 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".{{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}} Some scholars have argued for increased protections for cephalopods in the United States as well.{{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}}

• Animal cognition
• Animal consciousness
• Octopolis and Octlantis

{{clear}}

{{reflist}}

• [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|pages=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=978-0374227760|lccn=2016016696|author-link=Peter Godfrey-Smith}}

{{animal cognition}}

Category:Animal intelligence

Intelligence