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| BENJAMIN IS MLG GUSTARINOE | |||
| {{About|the order of cephalopod}} | |||
| <!-- | |||
| NOTE: This article uses the common pluralization "octopuses". This is correct and intentional; please do not change it. Other variants are discussed in the Etymology and pluralization section. | |||
| --> | |||
| {{Automatic taxobox | |||
| | fossil_range = {{Fossil range|323.2|0}}<small>] – Recent</small> | |||
| | image = Octopus2.jpg | |||
| | image_caption = The ], ''Octopus vulgaris''. | |||
| | taxon = Octopoda | |||
| | authority = ], 1818<ref>{{cite web|url=http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=82589 |title=ITIS Report: Octopoda Leach, 1818 |publisher=Itis.gov |date=2013-04-10 |accessdate=2014-02-04}}</ref> | |||
| | subdivision_ranks = ]s | |||
| | subdivision = | |||
| *] | |||
| *] | |||
| | synonyms = | |||
| * Octopoida<br /><small>Leach, 1817</small><ref>, Mikko's Phylogeny Archive: Coleoidea – Recent cephalopods</ref> | |||
| }} | |||
| An '''octopus''' ({{IPAc-en|ˈ|ɒ|k|t|ə|p|ʊ|s}} or {{IPAc-en|ˈ|ɒ|k|t|ə|p|ə|s}}; plural: '''octopuses''', '''octopi''',<!--redirect target, don't delete--> or '''octopodes'''; ]) is a ] ] of the ] '''Octopoda'''. It has two eyes and four pairs of arms and, like other cephalopods, it is ]. An octopus has a ], with its mouth at the center point of the arms. An octopus has no internal or external skeleton (although some species have a vestigial remnant of a shell inside their ]s,<ref>{{Cite journal|last1 =Semmens|title=Understanding octopus growth: patterns, variability and physiology|date=2004|doi =10.1071/MF03155}}</ref> allowing it to squeeze through tight places.<ref>{{cite web | url=http://animals.about.com/od/molluscs/a/octopus-facts.htm | title=Facts About Octopuses | accessdate=22 April 2014}}</ref> Octopuses are among the most intelligent and behaviorally diverse of all ]s. | |||
| Octopuses inhabit diverse regions of the ], including ]s, ] waters, and the ]. They have numerous strategies for defending themselves against predators, including the expulsion of ink, the use of ] and ]s, their ability to jet quickly through the water, and their ability to hide. An octopus trails its eight arms behind it as it swims. All octopuses are venomous, but only one group, the ], is known to be deadly to humans.<ref>, Tentacles of venom: new study reveals all octopuses are venomous, University of Melbourne, Media Release, Wednesday 15 April 2009</ref> | |||
| Around 300 ] are recognized, which is over one-third of the total number of known cephalopod species. The term 'octopus' may also be used to refer specifically to the ] '']''. | |||
| == Etymology and pluralization ==<!--Avoid changing. Used in links to subsection.--> | |||
| The ] term ''octopus'' was derived from ] ''ὀκτώπους'' (oktōpous), which literally translates to "eight-foot" (''ὀκτώ'' "eight" + ''πούς'' "foot").<ref name=etym>{{cite web|url=http://etymonline.com/?term=octopus |title=Online Etymology Dictionary |publisher=Etymonline.com |accessdate=2014-02-04}}</ref><ref>{{cite web|url=http://dictionary.reference.com/browse/octopus |title=Octopus | Define Octopus at Dictionary.com |publisher=Dictionary.reference.com |accessdate=2014-02-04}}</ref><ref>{{cite web|url=http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Do)ktw%2Fpous |title=Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'': ὀκτώπους |publisher=Perseus.tufts.edu |accessdate=2014-02-04}}</ref> Related to the word "octopus" are the term "Octopoda" (the ] of cephalopod molluscs that comprises the octopuses) and the adjective "octopoid".<ref name=OD/> | |||
| The standard ]ized form of "octopus" in the ] is "octopuses" {{IPA|/ˈɒktəpʊsɪz/}},<ref>{{cite journal|last1=Michel|first1=Jean-Baptiste|last2=Shen|first2=Yuan|last3=Aiden|first3=Aviva|last4=Veres|first4=Adrian|last5=Gray|first5=Matthew|last6=Pickett|first6=Joseph|last7=Hoiberg|first7=Dale|last8=Clancy|first8=Dan|last9=Norvig|first9=Peter|last10=Orwant|first10=Jon|last11=Pinker|first11=Steven|last12=Nowak|first12=Martin|last13=The Google Books Team|title=Quantitative Analysis of Culture Using Millions of Digitized Books|journal=Science|date=14 January 2011|volume=331|issue=6014|pages=176–182|accessdate=18 February 2015|postscript=. .}}</ref> although the Ancient Greek plural "octopodes" {{IPA|/ɒkˈtɒpədiːz/}}, has also been used historically.<ref name=OD>{{cite web|url=http://oxforddictionaries.com/definition/english/octopus |title=Octopus|publisher=Oxforddictionaries.com |date=2014-01-30 |accessdate=2014-02-04}}</ref> The alternative plural "octopi" — which ] it is a ] "]"-word — is considered grammatically incorrect.<ref>Peters, Pam (2004). ''The Cambridge Guide to English Usage''. Cambridge: Cambridge University Press. ISBN 0-521-62181-X, p. 388.</ref><ref>'']'' states that the only acceptable plural in English is "octopuses", that "octopi" is misconceived, and "octopodes" ].</ref><ref> (retrieved 19 October 2007)</ref><ref>{{cite AV media |people= Kory Stamper |title= Ask the editor: octopus |url= http://www.merriam-webster.com/video/0015-octopus.htm |accessdate= 26 June 2013 |publisher= Merriam-Webster }}</ref> It is nevertheless used enough to make it notable, and was formally acknowledged by the ] ''Merriam-Webster 11th Collegiate Dictionary'' and ''Webster's New World College Dictionary''. The '']'' (2008 Draft Revision)<ref> (subscription required). Retrieved 1 February 2010.</ref> lists "octopuses", "octopi", and "octopodes", in that order, labelling "octopodes" as rare and noting that "octopi" derives from the misapprehension that ''octōpus'' comes from Latin.<ref>{{OED|centipede}}</ref> In contrast, '']'' (3rd Edition 2010) lists "octopuses" as the only acceptable pluralization, with a usage note indicating "octopodes" as being still occasionally used but "octopi" as being incorrect.<ref name=NOAD>{{cite book|title=New Oxford American Dictionary|year=2010|publisher=Oxford University Press|isbn=9780195392883|edition=3rd|editor=Angus Stevenson & Christine A. Lindberg|accessdate=2014-01-02}}</ref> | |||
| == Biology == | |||
| ] | |||
| ] (''Octopus vulgaris'')]] | |||
| Octopuses are characterized by their eight ], usually bearing ]s. The arms of octopuses are often distinguished from the pair of feeding ]s found in ] and ].<ref>Norman, M. 2000. ''Cephalopods: A World Guide''. ConchBooks, Hackenheim. p. 15. ISBN 978-3-925919-32-9 "There is some confusion around the terms ''arms'' versus ''tentacles''. The numerous limbs of ]es are called tentacles. The ring of eight limbs around the mouth in cuttlefish, squids and octopuses are called ''arms''. Cuttlefish and squid also have a pair of specialized limbs attached between the bases of the third and fourth arm pairs . These are known as ''feeding tentacles'' and are used to shoot out and grab prey."</ref> Both types of limb are ]s. Unlike most other cephalopods, the majority of octopuses – those in the suborder most commonly known, ] – have almost entirely soft bodies with no internal ]. They have neither a protective outer ] like the ], nor any vestige of an internal shell or ]s, like cuttlefish or squid. The ], similar in shape to a ]'s beak, and made of ], is the only hard part of their bodies. This enables them to squeeze through very narrow slits between underwater rocks, which is very helpful when they are fleeing from ]s or other predatory fish. The octopuses in the less-familiar ] suborder have ] and an ], generally reducing their ability to squeeze into small spaces. These cirrate species are often free-swimming and live in deep-water habitats, while incirrate octopus species are found in reefs and other shallower seafloor habitats. | |||
| Octopuses have a relatively short ], with some species living for as little as six months. Larger species, such as the ], may live for up to five years under suitable circumstances. However, reproduction is a cause of death: males can live for only a few months after mating, and females die shortly after their eggs hatch. They neglect to eat during the (roughly) one-month period spent taking care of their unhatched eggs, eventually dying of starvation. In a scientific experiment, the removal of both ]s after spawning was found to result in the cessation of ], the resumption of feeding, increased growth, and greatly extended lifespans.<ref name="hormones">{{cite journal | journal = ] | last1 = Wodinsky | first1 = Jerome | title = Hormonal Inhibition of Feeding and Death in Octopus: Control by Optic Gland Secretion | date = 2 December 1977 | volume = 198 | issue = 4320| pages = 948–951 | url = http://www.sciencemag.org/content/198/4320/948.abstract | accessdate= 27 November 2011 | doi = 10.1126/science.198.4320.948 | pmid=17787564}}</ref> | |||
| ]'', a finned octopus of the suborder ]]] | |||
| Octopuses have three ]s. Two ]s pump blood through each of the two ]s, while the third is a ] that pumps blood through the body. Octopus ] contains the ]-rich protein ] for transporting ]. Although less efficient under ] than the ]-rich ] of vertebrates, in cold conditions with low oxygen pressure, hemocyanin oxygen transportation is more efficient than hemoglobin oxygen transportation. The hemocyanin is dissolved in the ] instead of being carried within ]s, and gives the blood a bluish color. The octopus draws water into its mantle cavity, where it passes through its gills. As ], their gills are finely divided and vascularized outgrowths of either the outer or the inner body surface. | |||
| === Intelligence === | |||
| {{Main|Cephalopod intelligence}} | |||
| Octopuses are highly ], possibly more so than any other order of ]s. The exact extent of their intelligence and learning capability is much debated among biologists,<ref name = "ham"/><ref name="doug">, Is the octopus really the invertebrate intellect of the sea, by Doug Stewart. In: National Wildlife. Feb/Mar 1997, vol.35 no.2. URL is not the source | |||
| </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 |publisher=Web.archive.org |date=2008-01-02 |accessdate=2014-02-04 |deadurl=yes |archiveurl=https://web.archive.org/20120825030432/http://nationalzoo.si.edu/Support/AdoptSpecies/AnimalInfo/GiantOctopus/default.cfm |archivedate=25 August 2012 }}</ref><ref>, How Smart is the Octopus?</ref> but maze and ] experiments have shown evidence of a memory system that can store both ] and ]. It is not known precisely what contribution learning makes to adult octopus behavior. Young octopuses learn almost no behaviors from their parents, with whom they have very little contact.{{citation needed|date=March 2015}} | |||
| An octopus has a highly complex ], only part of which is localized in its ]. Two-thirds of an octopus's ]s are found in the nerve cords of its arms, which have limited functional autonomy. Octopus arms show a variety of complex ] actions that persist even when they have no input from the brain.<ref>{{cite journal | pmid = 15829594 | doi=10.1152/jn.00684.2004 | volume=94 | issue=2 | title=Dynamic model of the octopus arm. I. Biomechanics of the octopus reaching movement |date=August 2005 | journal=J. Neurophysiol. | pages=1443–58}}</ref> Unlike vertebrates, the complex motor skills of octopuses are not organized in their brain using an internal ] of its body, instead using a nonsomatotopic system unique to large-brained invertebrates.<ref>{{cite journal | pmid = 19765993 | doi=10.1016/j.cub.2009.07.067 | volume=19 | issue=19 | title=Nonsomatotopic organization of the higher motor centers in octopus |date=October 2009 | pages=1632–6}}</ref> Despite this delegation of control, octopus arms do not become tangled or stuck to each other because the suction cups have chemical sensors that recognize octopus skin and prevent self-attachment.<ref>http://www.npr.org/2014/05/15/312575546/why-this-octopus-isnt-stuck-up</ref> Some octopuses, such as the ], will move their arms in ways that emulate the shape and movements of other ]. | |||
| In laboratory experiments, octopuses can be readily trained to distinguish between different shapes and patterns. They have been reported to practice ],<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/europe/2796607.stm |title=Octopus intelligence: jar opening |publisher=BBC News |date=2003-02-25 |accessdate=2014-02-04}}</ref> although the validity of these findings is widely contested on a number of grounds.<ref name="ham">{{cite web | |||
| | last = Hamilton | |||
| | first = Garry | |||
| | authorlink = | |||
| | title = What is this octopus thinking? | |||
| | work = | |||
| | publisher = | |||
| | date = | |||
| | url = http://www.fortunecity.com/emachines/e11/86/cephpod.html | |||
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| | archiveurl = http://web.archive.org/web/20120407062518/http://www.fortunecity.com/emachines/e11/86/cephpod.html | |||
| | archivedate = 7 April 2012 }} | |||
| </ref><ref name="doug"/> Octopuses have also been observed in what some have described as ]: repeatedly releasing bottles or toys into a circular current in their aquariums and then catching them.<ref>. By Dr. Jennifer Mather, Department of Psychology and Neuroscience, ] and Roland C. Anderson, The ].</ref> Octopuses often break out of their aquariums and sometimes into others in search of food.<ref>{{cite journal |url=http://www.thecephalopodpage.org/_pdf/2004Escape.pdf |title=Interspecific Evaluation of Octopus Escape Behavior |author1=Wood, James B. |author2=Anderson, Roland C. |date=2004 |journal=Journal of Applied Animal Welfare Science |pages=95–106 |volume=7 |number=2 |publisher=Lawrence Erlbaum Associates |accessdate=11 September 2015 |doi=10.1207/s15327604jaws0702_2}}</ref><ref>{{cite book |url=https://books.google.com/books?id=lD8DAAAAQAAJ&pg=PA38#v=onepage&q&f=false |title=Aquarium Notes — The Octopus; or, the "devil-fish" of fiction and of fact |author=Lee, Henry |chapter=V: The octopus out of water |date=1875 |publisher=Chapman and Hall |oclc=1544491 |location=London |accessdate=11 September 2015 |pages=38–39 |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.}}</ref> They have even boarded ]s and opened holds to eat crabs.<ref name="denizen" /> | |||
| ==== Tool use ==== | |||
| ]'' travels with shells it has collected for protection]] | |||
| The octopus has been shown to ]. At least four specimens of the veined octopus ('']'') have been witnessed retrieving discarded ] shells, manipulating them, and then reassembling them to use as shelter.<ref>{{cite news| url=http://news.bbc.co.uk/1/hi/sci/tech/8408233.stm | work=BBC News | title=Octopus snatches coconut and runs | date=2009-12-14 | accessdate=2010-05-20}}</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 |publisher=Edutube.org |accessdate=2014-02-04}}</ref><ref>{{Cite journal | |||
| | pmid = 20064403 | |||
| | year = 2009 | |||
| | author1 = Finn | |||
| | first1 = J. K. | |||
| | title = Defensive tool use in a coconut-carrying octopus | |||
| | journal = Current Biology | |||
| | volume = 19 | |||
| | issue = 23 | |||
| | pages = R1069–70 | |||
| | last2 = Tregenza | |||
| | first2 = T | |||
| | last3 = Norman | |||
| | first3 = M. D. | |||
| | doi = 10.1016/j.cub.2009.10.052 | |||
| }}</ref> | |||
| ====Protective legislation==== | |||
| Due to their intelligence, octopuses in some countries are on the list of ] on which surgery may not be performed without ], a protection usually extended only to vertebrates. In the UK from 1993 to 2012, the common octopus (''Octopus vulgaris'') was the only invertebrate protected under the ].<ref>{{cite web|title=The Animals (Scientific Procedures) Act (Amendment) Order 1993|url=http://www.legislation.gov.uk/uksi/1993/2103/article/3/made#text%3D%22Octopus%22|publisher=The National Archives|accessdate=18 February 2015}}</ref> In 2012, this legislation was extended to include all cephalopods<ref>{{cite web|title=The Animals (Scientific Procedures) Act 1986 Amendment Regulations 2012|url=http://www.legislation.gov.uk/uksi/2012/3039/regulation/3/made|publisher=The National Archives|accessdate=18 February 2015}}</ref> in accordance with a general ] directive.<ref>{{cite web|title=DIRECTIVE 2010/63/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL|url=http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:276:0033:0079:EN:PDF|publisher=Official Journal of the European Union|accessdate=18 February 2015|location=Article 1, 3(b)}}</ref> | |||
| === Defense === | |||
| ] (''Hapalochlaena lunulata'')]] | |||
| An octopus's primary defense is to hide or to disguise itself through ] and ].<ref name=behaviour>Hanlon, R.T. & J.B. Messenger 1996. ''Cephalopod Behaviour''. Cambridge University Press, Cambridge.</ref> Octopuses have several secondary defenses (defenses they use once they have been seen by a predator). The most common secondary defense is fast escape. Other defenses include distraction with the use of ]s and ]. | |||
| Most octopuses can eject a thick, blackish ] in a large cloud to aid in escaping from predators. The main coloring agent of the ink is ], which is the same chemical that gives humans their ] and ]. This ink cloud is thought to reduce the efficiency of olfactory organs, which would aid an octopus's evasion from predators that employ ] for hunting, such as ]s. Ink clouds of some species might serve as pseudomorphs, or decoys that the predator attacks instead.<ref>{{Cite journal | last1 = Caldwell | first1 = R. L. | year = 2005 | title = An Observation of Inking Behavior Protecting Adult ''Octopus bocki'' from Predation by Green Turtle (''Chelonia mydas'') Hatchlings | url = | journal = Pacific Science | volume = 59 | issue = 1| pages = 69–72 | doi = 10.1353/psc.2005.0004 }}</ref> | |||
| An octopus's camouflage is aided by certain specialized skin cells which can change the apparent color, opacity, and reflectivity of the epidermis. ]s contain yellow, orange, red, brown, or black pigments; most species have three of these colors, while some have two or four. Other color-changing cells are reflective ]s, and ]s (white).<ref>{{cite web | url = http://www.dnr.sc.gov/marine/sertc/species_month.htm | title = Tales from the Cryptic: The Common Atlantic Octopus | accessdate = 2006-07-27 | author = Meyers, Nadia|publisher = Southeastern Regional Taxonomic Center}}</ref> This color-changing ability can also be used to communicate with or warn other octopuses. The highly venomous ] becomes bright yellow with blue rings when it is provoked. Octopuses can use muscles in the skin to change the texture of their mantle to achieve a greater camouflage. In some species, the mantle can take on the spiky appearance of seaweed, or the scraggly, bumpy texture of a rock, among other disguises. However, in some species, skin anatomy is limited to relatively patternless shades of one color, and limited skin texture. It is thought that octopuses that are day-active and/or live in complex habitats such as coral reefs have evolved more complex skin than their nocturnal and/or sand-dwelling relatives.<ref name=behaviour /> | |||
| When under attack, some octopuses can perform arm ], in a manner similar to the way ]s and other ]s detach their tails. The crawling arm serves as a distraction to would-be predators. Such severed arms remain sensitive to stimuli and move away from unpleasant sensations.<ref>. Octopus Chronicles, Scientific American Blog Network.</ref> | |||
| A few species, such as the ], have a fourth defense mechanism. They can combine their highly flexible bodies with their color-changing ability to accurately mimic other, more dangerous animals, such as ], ], and ]s.<ref>{{cite journal | last1=Norman | first1= MD| last2= Finn | first2= J| last3= Tregenza | first3= T |title=Dynamic mimicry in an Indo-Malayan octopus |journal=Proceedings of the Royal Society |volume=268 |issue=1478 |pages=1755–8 |date=September 2001 |pmid=11522192 |pmc=1088805 |doi=10.1098/rspb.2001.1708 |url=http://marinebio.org/upload/files/mimic.pdf }}</ref><ref>{{cite journal | last1 = Norman | first1 = M.D. | year = 2005 | title = The "Mimic Octopus" (''Thaumoctopus mimicus'' n. gen. et sp.), a new octopus from the tropical Indo-West Pacific (Cephalopoda: Octopodidae) | url = http://www.mapress.com/mr/content/v25/2005f/n2p070.htm | journal = Molluscan Research | volume = 25 | issue = | pages = 57–70 }}</ref> | |||
| <!--=== Diet === | |||
| Octopuses usually eat small crabs and scallops, plus some snails, fish, turtles, crustaceans (like shrimp), and other octopuses. They catch prey with their arms, then kill it by biting it with their tough beak, paralysing the prey with a nerve poison, and softening the flesh. They then suck out the flesh. Octopuses hunt mostly at night. Only the Australian Blue-ringed octopus has a poison strong enough to kill a person.<ref>http://www.enchantedlearning.com/subjects/invertebrates/octopus/Octopuscoloring.shtml</ref>--> | |||
| === Reproduction === | |||
| When octopuses reproduce, the male uses a specialized arm called a ] to transfer ]s (packets of sperm) from the terminal organ of the reproductive tract (the cephalopod "penis") into the female's mantle cavity.<ref name=TOL>Young, R.E., M. Vecchione & K.M. Mangold 1999. . Tree of Life web project.</ref> The hectocotylus in ] octopuses is usually the third right arm. Males die within a few months of mating. In some species, the female octopus can keep the sperm alive inside her for weeks until her eggs are mature. After they have been fertilized, the female lays about 200,000 eggs (this figure dramatically varies between families, genera, species and also individuals).{{citation needed|date=July 2012}} | |||
| === Senses === | |||
| ]'']] | |||
| Octopuses have keen eyesight. Like other cephalopods, they can distinguish the ] of light. ] appears to vary from species to species, being present in ''O. aegina'' but absent in ''O. vulgaris''.<ref>{{cite journal | last1 = Kawamura | first1 = G.| year = 2001 | title = Color Discrimination Conditioning in Two Octopus ''Octopus aegina'' and ''O. vulgaris | url = http://rms1.agsearch.agropedia.affrc.go.jp/contents/JASI/pdf/society/62-1620.pdf | journal = Nippon Suisan Gakkashi | volume = 67 | issue = 1| pages = 35–39 | doi=10.2331/suisan.67.35|display-authors=etal}}</ref> Attached to the brain are two special organs, called ]s, that allow the octopus to sense the orientation of its body relative to horizontal. An ] response keeps the octopus's eyes oriented so the pupil slit is always horizontal.{{citation needed|date=July 2012}} | |||
| Octopuses also have an excellent ]. An octopus's suction cups are equipped with ] so the octopus can ] what it is touching. The arms contain ] sensors so the octopus knows whether its arms are stretched out. However, it has a very poor ] sense. The tension receptors are not sufficient for the brain to determine the position of the octopus's body or arms. (It is not clear whether the octopus brain would be capable of processing the large amount of information that this would require; the flexibility of an octopus's arms is much greater than that of the limbs of vertebrates, which devote large areas of ] to the processing of proprioceptive inputs.) As a result, the octopus does not possess ]; that is, it does not form a ] of the overall shape of the object it is handling. It can detect local texture variations, but cannot integrate the information into a larger picture.<ref name="wells">Wells. Martin John. ''Octopus: physiology and behaviour of an advanced invertebrate''. London : ]; New York : distributed in the U.S.A. by Halsted Press, 1978.</ref> | |||
| The neurological autonomy of the arms means the octopus has great difficulty learning about the detailed effects of its motions. The brain may issue a high-level command to the arms, but the nerve cords in the arms execute the details. There is no neurological path for the brain to receive ] feedback about just how its command was executed by the arms; the only way it knows just what motions were made is by observing the arms visually, i.e. ].<ref name="wells"/> | |||
| Octopuses might use the ] (a sac-like structure containing a mineralised mass and sensitive hairs) to register sound. The common octopus can hear sounds between 400 Hz and 1000 Hz, and hears best at a frequency of 600 Hz.<ref>{{cite news|url=http://news.bbc.co.uk/earth/hi/earth_news/newsid_8095000/8095977.stm|title=The cephalopods can hear you |publisher=BBC|date=15 June 2009|author=Matt Walker|accessdate = 2013-07-19}}</ref> | |||
| === Locomotion === | |||
| ] | |||
| ] | |||
| Octopuses move about by crawling or swimming. Their main means of slow travel is crawling, with some swimming. ] is their fastest means of locomotion, followed by swimming and walking.<ref name="biologists2006">{{cite web|author=Christine L. Huffard |url=http://jeb.biologists.org/cgi/content/abstract/209/19/3697 |title=Locomotion by ''Abdopus aculeatus''|publisher=Jeb.biologists.org |date=2006-10-01 |accessdate=2014-02-04}}</ref> | |||
| They crawl by walking on their arms, usually on many at once, on both solid and soft surfaces, while supported in water. In 2005, some octopuses ('']'' and '']'' under current taxonomy) were found to walk on two arms, while at the same time resembling plant matter.<ref>{{cite journal | doi = 10.1126/science.1109616 | title = Underwater Bipedal Locomotion by Octopuses in Disguise | year = 2005 | last1 = Huffard | first1 = C. L. | journal = Science | volume = 307 | issue = 5717 | page = 1927 | pmid = 15790846 | last2 = Boneka | first2 = F | last3 = Full | first3 = RJ }}</ref> This form of locomotion allows these octopuses to move quickly away from a potential predator while possibly not triggering that predator's search image for octopus (food).<ref name="biologists2006"/> A study of this behavior conducted by the ] led to the suggestion that the two rearmost appendages may be more accurately termed 'legs' rather than 'arms'.<ref> ''Hindustan Times, 8/3/2008''</ref> Some species of octopus can crawl out of the water for a short period, which they may do between ]s while hunting crustaceans or gastropods or to escape predators.<ref>{{cite web|url=http://blogs.scientificamerican.com/octopus-chronicles/2011/11/24/land-walking-octopus-explained-video/|title=Land-Walking Octopus Explained|last=Harmon|first=Katherine|date=24 November 2011|work=Octopus Chronicles|publisher=Scientic American blogs|accessdate=24 November 2011}}</ref><ref>{{cite journal|last=Wood|first=James B.|author2=Roland C. Anderson|year=2004|title=Interspecific Evaluation of Octopus Escape Behavior|journal=Journal of Applied Animal Welfare Science|publisher=Lawrence Erlbaum Associates, Inc.|volume=7|issue=2|pages=95–106|url=http://www.animalsandsociety.org/assets/library/186_s15327604jaws07022.pdf|doi=10.1207/s15327604jaws0702_2|pmid=15234886}}</ref> | |||
| Octopuses swim by expelling a jet of water from a contractile ], and aiming it via a muscular ]. | |||
| === Diet === | |||
| Bottom-dwelling octopuses eat mainly crabs, ]s, and other molluscs such as ]s and ]s. Open-ocean octopuses eat mainly prawns, fish and other cephalopods. They usually inject their prey with a paralysing saliva before dismembering it into small pieces with their beaks.<ref>Wassilieff, Maggy; and O’Shea, Steve (2009) ''Te Ara – the Encyclopedia of New Zealand''. Updated 2 March 2009.</ref> Octopuses feed on shelled molluscs either by using force, or by drilling a hole in the shell, injecting a secretion into the hole, and then extracting the soft body of the mollusc.<ref>{{cite journal | last1 = Wodinsky | first1 = Jerome | year = 1969 | title = Penetration of the Shell and Feeding on Gastropods by Octopus | url = http://icb.oxfordjournals.org/content/9/3/997.short | journal = Amer. Zool. | volume = 9 | issue = 3| pages = 997–1010 | doi = 10.1093/icb/9.3.997 }}</ref> | |||
| Large octopuses have also been known to catch and kill some species of ]s.<ref>, from The Octopus Show by ]</ref> Seabirds have also been documented as prey.<ref>https://www.youtube.com/watch?v=LNwegprmtx8</ref> | |||
| === Size === | |||
| {{See also|Cephalopod size}} | |||
| The ], ''Enteroctopus dofleini'', is often cited as the largest known octopus species. Adults usually weigh around 15 kg (33 lb), with an arm span of up to 4.3 m (14 ft).<ref name="FONZ">{{cite web|url=http://nationalzoo.si.edu/Animals/Invertebrates/Facts/cephalopods/FactSheets/Pacificoctopus.cfm |title=Smithsonian National Zoological Park: Giant Pacific Octopus |publisher=Nationalzoo.si.edu |accessdate=2014-02-04}}</ref> The largest specimen of this species to be scientifically documented was an animal with a live mass of 71 kg (156.5 lb).<ref>Cosgrove, J.A. 1987. Aspects of the Natural History of ''Octopus dofleini'', the Giant Pacific Octopus. M.Sc. Thesis. Department of Biology, University of Victoria (Canada), 101 pp.</ref> The alternative contender is the ], ''Haliphron atlanticus'', based on a 61 kg (134 lb) carcass estimated to have a live mass of 75 kg (165 lb).<ref>{{cite journal | last1 = O'Shea | first1 = S. | year = 2004 | title = The giant octopus ''Haliphron atlanticus'' (Mollusca : Octopoda) in New Zealand waters | doi = 10.1080/03014223.2004.9518353 | journal = New Zealand Journal of Zoology | volume = 31 | issue = 1| pages = 7–13 }}</ref><ref>{{cite journal | last1 = O'Shea | first1 = S. | year = 2002 | title = ''Haliphron atlanticus'' — a giant gelatinous octopus | url =http://isopods.nhm.org/pdfs/27566/27566.pdf | journal = Biodiversity Update | volume = 5 | issue = | page = 1 }}</ref> However, a number of questionable size records would suggest ''E. dofleini'' is the largest of all known octopus species by a considerable margin;<ref name=norman03>Norman, M. 2000. ''Cephalopods: A World Guide''. ConchBooks, Hackenheim. p. 214.</ref> one such record is of a specimen weighing 272 kg (600 lb) and having an arm span of 9 m (30 ft).<ref>{{Cite journal | last1 = High | first1 = W.L. | year = 1976 | title = The giant Pacific octopus | url = | journal = U.S. National Marine Fisheries Service, Marine Fisheries Review | volume = 38 | issue = 9| pages = 17–22 }}</ref> | |||
| == Relationship to humans == | |||
| ] clay vase showing an octopus, ''circa'' 1500 BCE]] | |||
| Ancient peoples of the ] were aware of the octopus, as evidenced by certain artworks and designs of prehistory. For example, a stone carving found in the archaeological recovery from ] ] ] at ] (1900 – 1100 BC) has a depiction of a fisherman carrying an octopus.<ref>C. Michael Hogan. 2007 </ref> | |||
| In classical Greece, ] (384 BC – 322 BC) commented on the colour-changing abilities of the octopus, both for camouflage and for ], in his '']'':<ref name=Aristotle>Aristotle (c. 350 BC). ''Historia Animalium''. IX, 622a: 2–10. Cited in Borrelli, Luciana; Gherardi, Francesca; Fiorito, Graziano (2006). ''A catalogue of body patterning in Cephalopoda''. Firenze University Press. ISBN 978-88-8453-377-7. </ref> | |||
| {{quote|The octopus ... seeks its prey by so changing its colour as to render it like the colour of the stones adjacent to it; it does so also ].|Aristotle<ref name=Aristotle/>}} | |||
| Octopuses were often depicted in the art of the ] people of ancient ], who worshipped the sea and its animals.<ref>Berrin, Katherine & Larco Museum. ''The Spirit of Ancient Peru:Treasures from the ].'' New York: ], 199 7.</ref> | |||
| === In mythology === | |||
| The ] of ] has been thought to have been inspired by the octopus or squid, the octopus itself representing the severed head of ], the beak as the protruding tongue and fangs, and its tentacles as the snakes.<ref>{{cite book|url=http://books.google.com/books?isbn=019988773X|title=Medusa:Solving the Mystery of the Gorgon|last=Wilk|first=Stephen R.|year=2000|publisher=Oxford University Press|isbn=019988773X}}</ref> | |||
| The ] are legendary sea monsters of giant proportions said to dwell off the coasts of ] and ], usually portrayed in art as a giant octopus attacking ships. | |||
| The ]an ] relates that the present cosmos is only the last of a series, having arisen in stages from the wreck of the previous universe. In this account, the octopus is the lone survivor of the previous, alien universe.<ref name=Dixon>{{cite book| title = The Mythology of All Races: Oceanic | volume = 9| last = Dixon | first = Roland Burrage| year = 1916| publisher = Marshall Jones| page = 15| authorlink = Roland Burrage Dixon}}</ref> | |||
| ] is a gigantic octopus-like ] from ] folklore, which supposedly lurks in ] in ] and has been sighted in several locations including Taiwan and Korea since the 19th century.<ref name="Swancer">Swancer, Brent via Coleman, Loren. Akkorokamui. Cryptomundo. http://www.cryptomundo.com/cryptozoo-news/akkorokamui</ref> | |||
| In Japanese mythology and folklore there is a ] called the ], that is an octopus with seven tentacles. | |||
| === In literature === | |||
| The octopus has a significant role in ]'s book ''Travailleurs de la mer'' ('']'').<ref>{{Cite EB1911|wstitle=Octopus}}</ref> | |||
| ]'s 1966 short story collection '']'', and the 1983 ] partly inspired by Hugo's book. | |||
| In ]'s novella '']'', the ] "Doc" is studying what the denizens of ] call "]". Doc's study of octopuses to ascertain whether their behavior displays emotional responses similar to humans, such as ], is a major plot device in the novella.<ref name="Sweet Thursday">{{cite web|title=Sweet Thursday - Plot Synopsis|url=http://sits.sjsu.edu/curriculum-resources/sweet-thursday/plot-synopsis/|website=STEINBECK IN THE SCHOOLS|publisher=SAN JOSÉ STATE UNIVERSITY|accessdate=5 January 2015}}</ref> | |||
| ], the marine biologist who was Steinbeck's friend and inspiration for the character Doc, had an octopus as a trademark for products sold by his ]. | |||
| ] wrote a 2014 children's book based on his 1969 song '']''. The book is illustrated by Ben Court.<ref name="Octopus's Garden">{{cite web|last1=Starr|first1=Ringo & Bud Cort|title=Octopus's Garden|url=http://books.simonandschuster.com/Octopuss-Garden/Ringo-Starr/9781481403627|publisher=Simon & Shuster|accessdate=5 January 2015}}</ref> | |||
| === As a metaphor === | |||
| Due to having numerous arms that emanate from a common center, the octopus is often used as a metaphor for a group or organization that is perceived as being powerful, manipulative or bent on domination. Use of this terminology is invariably negative and employed by the opponents of the groups or institutions so described.<ref>{{cite web|last=Palmer |first=Jessica |url=http://scienceblogs.com/bioephemera/2010/05/nazi_tentacles_a_brief_history.php |title=Nazi Tentacles: The octopus as visual metaphor |publisher=Scienceblogs.com |date=2010-05-30 |accessdate=2014-02-04}}</ref> | |||
| === As food === | |||
| {{Main|Octopus as food}} | |||
| Octopus is eaten in many cultures. They are a common food in Mediterranean and Asian sea areas.<ref>{{cite web|url=http://www.animalfactguide.com/animal-facts/common-octopus/|title=Common octupus| work=Animal fact guide}}</ref><ref>{{cite web|url=http://www.montereybayaquarium.org/animal-guide/octopus-and-kin/giant-pacific-octopus|title=Giant Pacific octopus|work= Montereybayaquar}}</ref> The arms and sometimes other body parts are prepared in various ways, often varying by species or geography. | |||
| === As pets === | |||
| Though octopuses can be difficult to keep in captivity, some people keep them as pets. They often escape even from supposedly secure tanks, due to their problem-solving skills, mobility and lack of rigid structure.{{citation needed|date=July 2012}} | |||
| The variation in size and lifespan among octopus species makes it difficult to know how long a new specimen can naturally be expected to live. That is, a small octopus may be just born or may be an adult, depending on its species. By selecting a well-known species, such as the ], one can choose a small octopus (around the size of a ]) and be confident it is young with a full life ahead of it.{{citation needed|date=July 2012}} | |||
| == Classification == | |||
| {{Wikispecies|Octopoda}} | |||
| ]'']] | |||
| ]'']] | |||
| * Class ] | |||
| ** Subclass ]: nautilus | |||
| ** Subclass ] | |||
| *** Superorder ]: ], ] | |||
| *** Superorder ] | |||
| **** Family †] <small>('']'')</small> | |||
| **** Order ]: vampire squid | |||
| **** '''Order Octopoda''' | |||
| ***** Genus †'']'' <small>('']'')</small> | |||
| ***** Genus †'']'' <small>('']'')</small> | |||
| ***** Genus †'']'' <small>('']'')</small> | |||
| ***** Genus †'']'' <small>('']'')</small> | |||
| ***** Genus †'']'' <small>('']'')</small> | |||
| ***** Genus †'']'' <small>('']'')</small> | |||
| ***** Suborder ]: finned ] octopus | |||
| ****** Family ]: umbrella octopus | |||
| ****** Family ] | |||
| ****** Family ] | |||
| ***** Suborder ] | |||
| ****** Superfamily ] | |||
| ******* Family ]: telescope octopus | |||
| ******* Family ]: gelatinous octopus | |||
| ******* Family ]: benthic octopus | |||
| ******** Genus '']'': giant octopus | |||
| ******** Genus Octopus | |||
| ******* Family ]: glass octopus | |||
| ****** Superfamily ] | |||
| ******* Family ]: seven-arm octopus | |||
| ******* Family ]: argonauts | |||
| ******* Family ]: tuberculate pelagic octopus | |||
| ******* Family ]: blanket octopus | |||
| == See also == | |||
| {{Misplaced Pages books|Cephalopoda}} | |||
| * ], a six-armed octopus | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ], famous for predicting football results in the ] | |||
| == References == | |||
| {{Reflist|30em}} | |||
| == External links == | |||
| {{Wikibooks|Dichotomous Key|Octopoda}} | |||
| {{Sister project links|octopus}} | |||
| * | |||
| * | |||
| * | |||
| * | |||
| * – footage of an octopus eating a shark () | |||
| * | |||
| * | |||
| * | |||
| * {{PDFlink||359 KB}} | |||
| * | |||
| * | |||
| {{commercial fish topics}} | |||
| {{Commercial molluscs}} | |||
| {{Edible molluscs}} | |||
| ] | |||
| ] | |||
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BENJAMIN IS MLG GUSTARINOE