Cephalopod intelligence is a measure of the cognitive ability of thecephalopod class ofmolluscs.
Intelligence is generally defined as the process of acquiring, storing, retrieving, combining, and comparing information and skills.[2] Though these criteria are difficult to measure in nonhuman animals, cephalopods are the most intelligentinvertebrates. The study of cephalopod intelligence also has an important comparative aspect in the broader understanding ofanimal cognition because it relies on a nervous system that is fundamentally different from that ofvertebrates.[3] In particular, theColeoidea subclass (cuttlefish,squid, andoctopuses) is thought to contain the most intelligentinvertebrates. It is also thought to be an important example of advanced cognitive evolution in animals, thoughnautilus intelligence is also a subject of growing interest among zoologists.[4]
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 impressivespatial learning capacity,navigational abilities, andpredatory techniques in cephalopods is widely acknowledged.[5][6] Cephalopods have been compared tointelligent extraterrestrials, due to theirconvergently evolved mammal-like intelligence.[7]
Cephalopods have large, well-developedbrains,[8][9][10] and theirbrain-to-body mass ratio is the largest among the invertebrates, falling between that ofendothermic andectothermic vertebrates.[10][11][12] The largenerve fibers of the cephalopodmantle have been widely used for many years as experimental material inneurophysiology; their large diameter (due to lack of amyelin sheath) makes them relatively easy to study compared with other animals.[13] An octopus's nerves are not limited to the brain. In fact, two-thirds of an octopus'sneurons are in the nerve cords of its arms. These are capable of complexreflex actions without input from the brain.[14]
Unlike most other molluscs, all cephalopods are active predators (with the possible exceptions of theBigfin squid andvampire squid). Their need to locate and capture their prey has likely been the driving force behind the development of their intelligence.[15]
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.[16][17]
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.[18][19][20]
Acuttlefish employing camouflage in its natural habitat.
Although believed[by whom?] to not be the most social of animals, some[which?] cephalopods are highly social creatures. When isolated from their own kind, some species have been observedshoaling with fish.[21]
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.[22] Some cephalopods are capable of rapid changes in skin colour and pattern usingchromatophores,iridophores, andleucophores.[23] This ability almost certainly evolved forcamouflage. However, some squid and cuttlefish use flashing colors and patterns to communicate with each other in various courtship rituals.[22]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.[24][25] Tests show that octopuses become more sociable when exposed to the psychoactive drugMDMA.[26]
TheHumboldt squid shows high amounts of cooperation and communication in its hunting techniques. This was one of the first observations of cooperative hunting in invertebrates.[27]
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.[28]
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 thatoctopuses are capable of usingobservational learning.[29] However, this is disputed by some.[30] Both octopuses andnautiluses are capable of vertebrate-likespatial learning.[31] Additionally, cuttlefish have been shown to have the capacity for future planning and reward processing after being tested with theStanford marshmallow experiment.[32]
At least four individuals of theVeined octopus (Amphioctopus marginatus) have been observed retrieving discardedcoconut shells, transporting them some distance, and then reassembling them for use as a shelter.[33] It is theorized that the octopuses used shells for the same purpose before humans made coconut shells widely available on the sea floor.[34][35] Other sea creatures construct homes in a similar manner; for example, mosthermit 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.[36])
Smaller individuals of theCommon blanket octopus (Tremoctopus violaceus) will hold the tentacles of thePortuguese man o' war (whose venom they are immune to), both as a means of protection and as a method of capturing prey.[37]
Octopuses have also been known to deliberately place stones, shells, and even bits of broken bottles to form walls that constrict their den openings.[38] In laboratory studies, theCaribbean dwarf octopus(Octopus mercatoris), a small pygmy species of octopus, has been observed to block its lair using plasticLego bricks.[39]
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.[1]
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.[40]
Cephalopods benefit fromenvironmental enrichment, which indicates behavioral and neuronal flexibility not exhibited by most other invertebrates.[41] For example, captive octopuses require stimulation or they will become lethargic.[42]
At theSea Star Aquarium inCoburg, 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 ashort circuit by shooting a jet of water at the overhead lamp.[43]
^Tricarico, Elena; Amodio, Piero; Ponte, Giovanna; Fiorito, Graziano (2014). "Cognition and recognition in the cephalopod molluscOctopus vulgaris: coordinating interaction with environment and conspecifics". In Witzany, Guenther (ed.).Biocommunication of Animals. Springer. pp. 337–349.doi:10.1007/978-94-007-7414-8_19.ISBN978-94-007-7413-1.LCCN2019748877.
^Lee, Henry (1875)."V: The octopus out of water".Aquarium Notes – The Octopus; or, the "devil-fish" of fiction and of fact. London: Chapman and Hall. pp. 38–39.OCLC1544491. Retrieved11 September 2015.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.
^Byrne, R.A.; Griebel, U.; Wood, J.B.; Mather, J.A. (2003). "Squids say it with skin: A graphic model for skin displays in Caribbean Reef Squid".Berliner Geowissenschaftliche Abhandlungen.3:29–35.
^Oinuma, Colleen, (14 April 2008). "Octopus mercatoris response behavior to novel objects in a laboratory setting: Evidence of play and tool use behavior?" InOctopus Tool Use and Play Behavior[1]
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.
Octopuses are Smart Suckers!? By Dr. Jennifer Mather, Department of Psychology and Neuroscience, University of Lethbridge and Roland C. Anderson, The Seattle Aquarium
