Temporal range: Early Pennsylvanian – Recent1
|The common octopus, Octopus vulgaris.|
The octopus (pron.: // or pron.: //; plural: octopuses, octopi, or octopodes; see below) is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms and, like other cephalopods, they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms. Octopuses have no internal or external skeleton (although some species have a vestigial remnant of a shell inside their mantles), allowing them to squeeze through tight places. Octopuses are among the most intelligent and behaviorally flexible of all invertebrates.
The octopus inhabits many diverse regions of the ocean, including coral reefs, pelagic waters, and the ocean floor. They have numerous strategies for defending themselves against predators, including the expulsion of ink, the use of camouflage and deimatic displays, 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 blue-ringed octopus, is known to be deadly to humans.4
Octopuses are characterized by their eight arms, usually bearing suction cups. The arms of octopuses are often distinguished from the pair of feeding tentacles found in squid and cuttlefish.5 Both types of limbs are muscular hydrostats. Unlike most other cephalopods, the majority of octopuses – those in the suborder most commonly known, Incirrina – have almost entirely soft bodies with no internal skeleton. They have neither a protective outer shell like the nautilus, nor any vestige of an internal shell or bones, like cuttlefish or squid. The beak, similar in shape to a parrot's beak, and made of chitin, 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 moray eels or other predatory fish. The octopuses in the less-familiar Cirrina suborder have two fins and an internal shell, 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 life expectancy, and some species live for as little as six months. Larger species, such as the giant pacific octopus, may live for up to five years under suitable circumstances. However, reproduction is a cause of death: males can only live for 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, removal of both optic glands after spawning was found to result in cessation of broodiness, resumption of feeding, increased growth, and greatly extended lifespans.6
Octopuses have three hearts. Two branchial hearts pump blood through each of the two gills, while the third is a systemic heart that pumps blood through the body. Octopus blood contains the copper-rich protein hemocyanin for transporting oxygen. Although less efficient under normal conditions than the iron-rich hemoglobin 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 plasma instead of being carried within red blood cells, and gives the blood a bluish color. The octopus draws water into its mantle cavity, where it passes through its gills. As mollusks, their gills are finely divided and vascularized outgrowths of either the outer or the inner body surface.
Octopuses are highly intelligent, possibly more so than any other order of invertebrates. The exact extent of their intelligence and learning capability is much debated among biologists,78910 but maze and problem-solving experiments have shown evidence of a memory system that can store both short- and long-term memory. 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.
An octopus has a highly complex nervous system, only part of which is localized in its brain. Two-thirds of an octopus's neurons are found in the nerve cords of its arms, which have limited functional autonomy. Octopus arms show a variety of complex reflex actions that persist even when they have no input from the brain.11 Unlike vertebrates, the complex motor skills of octopuses are not organized in their brain using an internal somatotopic map of its body, instead using a nonsomatotopic system unique to large-brained invertebrates.12 Some octopuses, such as the mimic octopus, will move their arms in ways that emulate the shape and movements of other sea creatures.
In laboratory experiments, octopuses can be readily trained to distinguish between different shapes and patterns. They have been reported to practice observational learning,13 although the validity of these findings is widely contested on a number of grounds.78 Octopuses have also been observed in what some have described as play: repeatedly releasing bottles or toys into a circular current in their aquariums and then catching them.14 Octopuses often break out of their aquariums and sometimes into others in search of food. They have even boarded fishing boats and opened holds to eat crabs.9
In some countries, octopuses are on the list of experimental animals on which surgery may not be performed without anesthesia. In the UK, the common octopus, (Octopus vulgaris), is the only invertebrate protected under the Animals (Scientific Procedures) Act 1986 and other cruelty to animals legislation, extending to them protections not normally afforded to invertebrates.15
The octopus is the only invertebrate which has been shown to use tools. At least four specimens of the veined octopus (Amphioctopus marginatus) have been witnessed retrieving discarded coconut shells, manipulating them, and then reassembling them to use as shelter. This discovery was documented in the journal Current Biology and has also been caught on video.1617
An octopus's main (primary) defense is to hide, either not to be seen at all, or through camouflage and mimicry not to be detected as an octopus.18 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 ink sacs and autotomising limbs.
Most octopuses can eject a thick, blackish ink in a large cloud to aid in escaping from predators. The main coloring agent of the ink is melanin, which is the same chemical that gives humans their hair and skin color. This ink cloud is thought to reduce the efficiency of olfactory organs, which would aid an octopus's evasion from predators that employ smell for hunting, such as sharks. Ink clouds of some species might serve as pseudomorphs, or decoys that the predator attacks instead.19
An octopus's camouflage is aided by certain specialized skin cells which can change the apparent color, opacity, and reflectiveness of the epidermis. Chromatophores 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 iridophores, and leucophores (white).20 This color-changing ability can also be used to communicate with or warn other octopuses. The very venomous blue-ringed octopus 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.18
A few species, such as the mimic octopus, 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 lionfish, sea snakes, and eels.2122
When octopuses reproduce, the male uses a specialized arm called a hectocotylus to insert spermatophores (packets of sperm) into the female's mantle cavity. The hectocotylus in benthic 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
Octopuses have keen eyesight. Like other cephalopods, they can distinguish the polarization of light. Color vision appears to vary from species to species, being present in O. aegina but absent in O. vulgaris.23 Attached to the brain are two special organs, called statocysts, that allow the octopus to sense the orientation of its body relative to horizontal. An autonomic response keeps the octopus's eyes oriented so the pupil slit is always horizontal.citation needed
Octopuses also have an excellent sense of touch. An octopus's suction cups are equipped with chemoreceptors so the octopus can taste what it is touching. The arms contain tension sensors so the octopus knows whether its arms are stretched out. However, it has a very poor proprioceptive 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 cerebral cortex to the processing of proprioceptive inputs.) As a result, the octopus does not possess stereognosis; that is, it does not form a mental image 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.24
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.24
Octopuses appear to have limited hearing.25
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 (Adopus aculeatus and Amphioctopus marginatus under current taxonomy) were found to walk on two arms, while at the same time resembling plant matter.27 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).26 A study of this behavior conducted by the Weymouth Sea Life Centre led to the suggestion that the two rearmost appendages may be more accurately termed 'legs' rather than 'arms'.28 Some species of octopuses can crawl out of the water for a short period, which they may do between tide pools while hunting crustaceans or gastropods or to escape predators.2930
Bottom-dwelling octopuses eat mainly crabs, polychaete worms, and other molluscs such as whelks and clams. 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.31 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.32
The giant Pacific octopus, Enteroctopus dofleini, is often cited as the largest octopus species. Adults usually weigh around 15 kg (33 lb), with an arm span of up to 4.3 m (14 ft).34 The largest specimen of this species to be scientifically documented was an animal with a live mass of 71 kg (156.5 lb).35 The alternative contender is the seven-arm octopus, Haliphron atlanticus, based on a 61 kg (134 lb) carcass estimated to have a live mass of 75 kg (165 lb).3637 However, a number of questionable size records would suggest E. dofleini is the largest of all octopus species by a considerable margin;38 one such record is of a specimen weighing 272 kg (600 lb) and having an arm span of 9 m (30 ft).39
Etymology and pluralization
The term "octopus" is from Greek ὀκτάπους4041 (oktapous, "eight-footed"), with traditional plural forms "octopuses" (pronounced /ˈɒktəpʊsɪz/) from English grammar and "octopodes" (pronounced /ɒkˈtɒpədiːz/) from the Greek. Currently, "octopuses" is the most common form in both the US and the UK. The term "octopod" (plural: "octopods" or "octopodes") is taken from the taxonomic order Octopoda, but has no classical equivalent. The collective plural "octopus" is usually reserved for animals consumed for food.citation needed
Some authorities consider "octopi" an objectionable42 hypercorrection, feeling the form arose from the incorrect assumption that "octopus" is a Latin second-declension form. However, "octopus" is a scientific Latin third-declension noun with a plural of octopodes. Nevertheless, the Oxford English Dictionary (2008 Draft Revision)43 lists "octopuses", "octopi", and "octopodes" (in that order), labelling "octopodes" 'rare' and noting that "octopi" derives from the misapprehension that octōpus is a second-declension Latin noun. The book further maintains that if the word were native to Latin, it would be third declension octōpēs (plural: octōpedes) after the pattern of pēs ("foot", plural pedēs).44 The original Latin word for octopus and other similar species is polypus, from Greek polýpous (πολύπους, "many-footed"); again, usually the inappropriate plural polypī is used instead of polypodēs.
Fowler's Modern English Usage states, 'the only acceptable plural in English is "octopuses"', that "octopi" is 'misconceived', and "octopodes" 'pedantic'. Chambers 21st Century Dictionary45 and the Compact Oxford Dictionary46 list only "octopuses", although the latter notes that "octopodes" is 'still occasionally used'. The descriptivist Merriam-Webster 11th Collegiate Dictionary lists "octopuses" and "octopi" in that order; likewise, Webster's New World College Dictionary lists in order "octopuses", "octopi", and "octopodes".
Relationship to humans
Ancient peoples of the Mediterranean 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 Bronze Age Minoan Crete at Knossos (1900 – 1100 BC) has a depiction of a fisherman carrying an octopus.47
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 when alarmed.—Aristotle.48
The Gorgon of Greek mythology has been thought to have been inspired by the octopus or squid, the octopus itself representing the severed head of Medusa, the beak as the protruding tongue and fangs, and its tentacles as the snakes.50
The Hawaiian creation myth 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.51
Akkorokamui (アッコロカムイ) is a gigantic octopus-like monster from Ainu folklore, which supposedly lurks in Funka Bay in Hokkaidō and has been sighted in several locations including Taiwan and Korea since the 19th century. 52
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 which 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.54
|Wikibooks Cookbook has a recipe/module on|
Humans eat octopus in many cultures. The arms and sometimes other body parts are prepared in various ways, often varying by species.
In Korea, some small species are sometimes eaten alive as a novelty food. A live octopus is usually sliced up, and it is eaten while still squirming.
Octopus is eaten regularly in Hawaii, since many popular dishes are Asian in origin. Locally known by their Hawaiian or Japanese names (he'e and tako, respectively), octopus is also a popular fish bait.
Octopus is a common food in Mediterranean cuisine and Portuguese cuisine. In Galicia, polbo á feira (market fair style octopus) is a local delicacy. Restaurants which specialize or serve this dish are known as pulperías. On the Tunisian island of Djerba, local people catch octopuses by taking advantage of the animals' habit of hiding in safe places during the night. In the evening, they put grey ceramic pots on the sea bed. The morning of the following day they check them for octopuses sheltered there. A common scene in the Greek islands is octopuses hanging in the sunlight from a rope, just like laundry from a clothesline. They are often caught by spear fishing close to the shore. The fisherman brings his prey to land and tenderizes the flesh by pounding the carcass against a stone surface. Thus treated, they are hung out to dry, and later will be served grilled, either hot or chilled in a salad. They are considered a superb meze, especially alongside ouzo.citation needed
According to the USDA Nutrient Database (2007), cooked octopus contains about 139 kilocalories (Calories) per three-ounce portion, and is a source of vitamin B3, B12, potassium, phosphorus, and selenium.55
Care must be taken to boil the octopus properly, to rid it of slime, smell, and residual ink.citation needed
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
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 California two-spot octopus, one can choose a small octopus (around the size of a tennis ball) and be confident it is young with a full life ahead of it.citation needed
|Wikispecies has information related to: Octopoda|
- Class Cephalopoda
- Subclass Nautiloidea: nautilus
- Subclass Coleoidea
- Superorder Decapodiformes: squid, cuttlefish
- Superorder Octopodiformes
- Family †Trachyteuthididae (incertae sedis)
- Order Vampyromorphida: vampire squid
- Order Octopoda
- Genus †Keuppia (incertae sedis)
- Genus †Palaeoctopus (incertae sedis)
- Genus †Paleocirroteuthis (incertae sedis)
- Genus †Pohlsepia (incertae sedis)
- Genus †Proteroctopus (incertae sedis)
- Genus †Styletoctopus (incertae sedis)
- Suborder Cirrina: finned deep-sea octopus
- Suborder Incirrina
- Family Amphitretidae: telescope octopus
- Family Bolitaenidae: gelatinous octopus
- Family Octopodidae: benthic octopus
- Family Vitreledonellidae: glass octopus
- Superfamily Argonautoida
- Octopus wrestling
- Legend of the Octopus
- Henry the Hexapus, a six-armed octopus
- Paul the Octopus, famous for predicting football results in the 2010 FIFA World Cup
- Kluessendorf, J.; Doyle, P. (2000). "Pohlsepia Mazonensis, an Early 'Octopus' from the Carboniferous of Illinois, USA". Palaeontology 43 (5): 919. doi:10.1111/1475-4983.00155.
- ITIS Report: Octopoda Leach, 1818
- Helsinki.fi, Mikko's Phylogeny Archive: Coleoidea – Recent cephalopods
- Unimelb.edu.au, Tentacles of venom: new study reveals all octopuses are venomous, University of Melbourne, Media Release, Wednesday 15 April 2009
- 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 nautiluses 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."
- Wodinsky, Jerome (2 December 1977). "Hormonal Inhibition of Feeding and Death in Octopus: Control by Optic Gland Secretion". Science 198 (4320): 948–951. doi:10.1126/science.198.4320.948. PMID 17787564. Retrieved 27 November 2011.
- What is this octopus thinking?. By Garry Hamilton.
- NFW.org?, Is the octopus really the invertebrate intellect of the sea, by Doug Stewart. In: National Wildlife. Feb/Mar 1997, vol.35 no.2.
- Giant Octopus—Mighty but Secretive Denizen of the Deep
- Slate.com, How Smart is the Octopus?
- "Dynamic model of the octopus arm. I. Biomechanics of the octopus reaching movement". J. Neurophysiol. 94 (2): 1443–58. August 2005. doi:10.1152/jn.00684.2004. PMID 15829594.
- Nonsomatotopic organization of the higher motor centers in octopus 19 (19). October 2009. pp. 1632–6. doi:10.1016/j.cub.2009.07.067. PMID 19765993.
- Octopus intelligence: jar opening
- 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.
- United Kingdom Animals (Scientific Procedures) act of 1986
- "Octopus snatches coconut and runs". BBC News. 2009-12-14. Retrieved 2010-05-20.
- Hanlon, R.T. & J.B. Messenger 1996. Cephalopod Behaviour. Cambridge University Press, Cambridge.
- Caldwell, R. L. (2005). "An Observation of Inking Behavior Protecting Adult Octopus bocki from Predation by Green Turtle (Chelonia mydas) Hatchlings". Pacific Science 59 (1): 69–72. doi:10.1353/psc.2005.0004.
- Meyers, Nadia. "Tales from the Cryptic: The Common Atlantic Octopus". Southeastern Regional Taxonomic Center. Retrieved 2006-07-27.
- Norman, MD; Finn, J; Tregenza, T (September 2001). "Dynamic mimicry in an Indo-Malayan octopus". Proceedings of the Royal Society 268 (1478): 1755–8. doi:10.1098/rspb.2001.1708. PMC 1088805. PMID 11522192.
- Norman, M.D. (2005). "The "Mimic Octopus" (Thaumoctopus mimicus n. gen. et sp.), a new octopus from the tropical Indo-West Pacific (Cephalopoda: Octopodidae)". Molluscan Research 25: 57–70.
- Kawamura, G. et al. (2001). "Color Discrimination Conditioning in Two Octopus Octopus aegina and O. vulgaris". Nippon Suisan Gakkashi 67 (1): 35–39.
- Wells. Martin John. Octopus: physiology and behaviour of an advanced invertebrate. London : Chapman and Hall; New York : distributed in the U.S.A. by Halsted Press, 1978.
- Matt Walker (15 June 2009). "The cephalopods can hear you". BBC. Retrieved 2010-04-02.
- Locomotion by Abdopus aculeatus, C.L. Huffard 2006
- Huffard, C. L.; Boneka, F; Full, RJ (2005). "Underwater Bipedal Locomotion by Octopuses in Disguise". Science 307 (5717): 1927. doi:10.1126/science.1109616. PMID 15790846.
- Octopuses have only six arms, the other two are actually legs! Hindustan Times, 8/3/2008
- Harmon, Katherine (24 November 2011). "Land-Walking Octopus Explained". Octopus Chronicles. Scientic American blogs. Retrieved 24 November 2011.
- Wood, James B.; Roland C. Anderson (2004). "Interspecific Evaluation of Octopus Escape Behavior". Journal of Applied Animal Welfare Science (Lawrence Erlbaum Associates, Inc.) 7 (2): 95–106. doi:10.1207/s15327604jaws0702_2. PMID 15234886.
- Wassilieff, Maggy; and O’Shea, Steve (2009) "Octopus and squid - Feeding and predation" Te Ara – the Encyclopedia of New Zealand. Updated 2 March 2009.
- Wodinsky, Jerome (1969). "Penetration of the Shell and Feeding on Gastropods by Octopus". Amer. Zool. 9 (3): 997–1010. doi:10.1093/icb/9.3.997.
- Archived Google video of an octopus catching a shark, from The Octopus Show by Mike deGruy
- Smithsonian National Zoological Park: Giant Pacific Octopus
- 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.
- O'Shea, S. (2004). "The giant octopus Haliphron atlanticus (Mollusca : Octopoda) in New Zealand waters". New Zealand Journal of Zoology 31 (1): 7–13. doi:10.1080/03014223.2004.9518353.
- O'Shea, S. (2002). "Haliphron atlanticus — a giant gelatinous octopus". Biodiversity Update 5: 1.
- Norman, M. 2000. Cephalopods: A World Guide. ConchBooks, Hackenheim. p. 214.
- High, W.L. (1976). "The giant Pacific octopus". U.S. National Marine Fisheries Service, Marine Fisheries Review 38 (9): 17–22.
- Oktapous, Henry George Liddell, Robert Scott, A Greek-English Lexicon, at Perseus
- Scientific Latin from Greek ὀκτώποδ-, ὀκτώπους (also ὀκτάποδ- ὀκτάπους) "eight-footed" > ὀκτώ- or ὀκτά- [combination form of ὀκτώ "eight"] and πόδ-, πούς "foot". Cf. Modern Greek χταπόδι < οκταπόδι < οκταπόδιον < ὀκτάπους.
- Peters, Pam (2004). The Cambridge Guide to English Usage. Cambridge: Cambridge University Press. ISBN 0-521-62181-X, p. 388.
- OED.com (subscription required). Retrieved February 1, 2010.
- "centipede". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005.
- Chambersharrap.co.uk, Retrieved October 19, 2007.
- Askoxford.com, Retrieved October 19, 2007.
- C. Michael Hogan. 2007 Knossos fieldnotes, The Modern Antiquarian
- 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. Abstract
- Berrin, Katherine & Larco Museum. The Spirit of Ancient Peru:Treasures from the Museo Arqueológico Rafael Larco Herrera. New York: Thames and Hudson, 199 7.
- Wilk, Stephen R. (2000). Medusa:Solving the Mystery of the Gorgon. Oxford University Press. ISBN 019988773X.
- Dixon, Roland Burrage (1916). The Mythology of All Races: Oceanic 9. Marshall Jones. p. 15.
- Swancer, Brent via Coleman, Loren. Akkorokamui. Cryptomundo. http://www.cryptomundo.com/cryptozoo-news/akkorokamui
- Chisholm, Hugh, ed. (1911). "Octopus". Encyclopædia Britannica (11th ed.). Cambridge University Press.
- Nazi Tentacles: The octopus as visual metaphor
- Octopus Calories And Nutrition
|The Wikibook Dichotomous Key has a page on the topic of: Octopoda|
|Find more about octopus at Wikipedia's sister projects|
|Definitions and translations from Wiktionary|
|Media from Commons|
|Learning resources from Wikiversity|
|News stories from Wikinews|
|Quotations from Wikiquote|
|Source texts from Wikisource|
|Textbooks from Wikibooks|
|Travel information from Wikivoyage|
- The Cephalopod Page
- TONMO.COM – The Octopus News Magazine Online
- Tree of Life website: information about cephalopods along with pictures and videos
- Discussion about the plural
- An octopus's shark encounter – footage of an octopus eating a shark (also in QuickTime format)
- Camouflage in action
- Video showing an Octopus escaping through a 1-inch (25 mm) hole
- Bipedal Octopuses- Video, Information, Original paper
- PDF (359 KB)
- Video of walking octopuses