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OctopusOctopus octopuses or octopiin general, any eight-armed cephalopod octopod mollusk of the Octopus Octopoda. The Octopus octopuses are members of the genus Octopusa large Octopus of Octopus distributed shallow-water cephalopods. See cephalopod. Octopuses vary greatly in size: the smallest, O. The typical octopus has a saccular body: the head is only slightly demarcated from the body and has large, complex eyes and eight contractile arms. Each arm bears two rows Octopus fleshy suckers that are capable of great holding power. Octopus arms are joined Octopus their bases by a web of tissue known as the skirt, at Octopus centre of which lies the mouth. The latter organ has a pair of sharp, horny beaks and a filelike organ, the radulafor drilling shells and rasping away flesh. The octopus takes water into its mantle and expels the water after respiration Octopus a short funnel or siphon. Most octopuses move by crawling Octopus the bottom with their arms Octopus suckers, though when alarmed they may shoot swiftly backward by ejecting Octopus jet of Octopus from the siphon. When endangered they eject an inky substancewhich is used as a screen; the substance produced by some species paralyzes the sensory organs of the attacker. The best-known octopus is the common octopusO. It lives in holes or crevices along the rocky bottom and is secretive and retiring by nature. It feeds mainly on crabs and Octopus crustaceans. This species is thought to be the most intelligent of all invertebrate animals. Each pigment-bearing cell chromatophore is individually innervated from the brain. The veined octopus Amphioctopus marginatus is also known for its intelligence. In biologists reported having observed the animals Octopus coconut half shells from the ocean floor and carrying them for use as portable shelters. Such behaviour is regarded by biologists as the first documented example of tool use by Octopus invertebrate. During the four to eight weeks required for the larvae to hatch, the female guards the Octopus, cleaning them with her suckers and agitating them with water. Upon hatching, the tiny octopods, which closely resemble their parents, spend several weeks drifting in the plankton before taking refuge on the Octopus. Octopuses feed mainly upon crabs and lobstersalthough some are plankton feeders, and they are Octopus upon by a number of marine fishes. They have long been considered Octopus culinary delicacy Octopus peoples of Octopus Mediterranean, Octopus Asia, and other parts of the world. Octopus Article Media Additional Info. Print Octopus. Facebook Twitter. Give Feedback External Websites. Let us know if you have suggestions Octopus improve this article requires login. Octopus Websites. Articles from Britannica Encyclopedias for elementary and Octopus school students. The Editors of Encyclopaedia Britannica Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree See Article History. At rest, the common octopus Octopus vulgaris blends into its surroundings. Read More on This Topic. The octopus, Octopus, cuttlefish, and chambered nautilus are familiar representatives. The extinct forms outnumber the living, the class having The common octopus Octopus vulgaris moving through water. How do "colour-blind" octopuses know what colour to change to in order to hide from predators Octopus to attract mates? The common octopus Octopus vulgaris may blanch when agitated. Get exclusive Octopus to content from our First Edition with your subscription. Subscribe today. Learn how Octopus traditional Greek dish of octopus and tomato sauce is made. Learn More in these related Britannica articles:. The Octopus forms outnumber the living, the class having attained great diversity in late Paleozoic and Mesozoic times. The extinct cephalopods are the ammonites, belemnites, and nautiloids, except for five living species of Nautilus. During this period she aerates the egg clusters and keeps them free of detritus, exhibiting remarkable behaviour for an animal that produces…. However, because there Octopus no lens and each photoreceptor must cover a wide angle of the field of view, the image in the Nautilus eye is of very poor resolution. Even with the pupil at its smallest, each receptor views an angle of more…. History at your fingertips. Sign up here to see what happened On This Dayevery day in your inbox! Email address. By signing up, you agree to our Privacy Notice. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Octopus Facts | Live Science

It's one of the most bizarre creatures Octopus Earth, and not just because it looks so different. Octopus octopus can camouflage itself in a flash; squeeze its entire body through a one-inch hole; and their brains? That's right, an octopus has one large central brain, and eight mini-brains, one in each arm. Play is Octopus of those characteristics Octopus higher minds. Rudy, a giant Pacific octopus, was one of the stars of the New Octopus Aquarium in Boston, before she passed away recently from old age. When correspondent Chip Reid Octopus last year, Rudy seemed to want to play with Octopus. Yes, Hollywood octopuses have torn down Octopus Golden Gate Bridge, destroyed ships, and feasted on movie stars. Montgomery says it's unfair to demonize them: Octopus would really have to go to outer space to come up with someone more different from us than Octopus. Their mouths are in their armpits; they have three hearts; they have Octopus blood. And the grace? I mean, who has grace like this? Montgomery spent countless hours studying these other-worldly beings while writing her book, "The Soul of an Octopus. Reid went behind the scenes to see for himself, with the help of senior aquarium biologist Bill Murphy. It Octopus out that calling an octopus Octopus is an understatement. It was as if she wanted Reid to join her in her octopus' garden. A big part of Murphy's job Octopus keeping Rudy from getting bored. There are about species of octopus, but the Octopus Pacific octopus is the largest, averaging 16 feet in length, and pounds. It's also the longest-lived octopus; even Octopus, its life span is only about three to five years. So, when you work this Octopus with them and you're interacting with them on a regular Octopus, you build a relationship with them. He's responsible for the care and feeding of the lab's octopuses, and Octopus up on their favorite food: tiny grass shrimp. Octopus at the lab, the day was about to get a lot better for a small California two-spot octopus — and a lot Octopus for one of those crabs. Of all the octopus' oddities, perhaps Octopus most extraordinary is its talent for disguise. The octopus changes its Octopus, colors, patterns, Octopus the texture of its skin, to look like seaweed, Octopus does it in the blink of an eye. It's called Octopus camouflage. Octopus is not a reflex; this is a decision-making process," Hanlon said. And they're calculating all along about what they're going to do next. As a scientist, Hanlon is skeptical about attributing human-like emotions to the octopus, or comparing their level of intelligence to ours. Octopus he says they are stunningly creative. A big brain in a Octopus and mysterious creature that scientists are only beginning to understand. Share Tweet Reddit Flipboard Email. Untangling the mysteries of the octopus. This story was originally broadcast January 12, Reid said, "Some people go, 'Eeeww, that's creepy. And that, she claims, is not the only Octopus they Octopus in common with humans. CBS News There are about species of octopus, but the giant Pacific octopus is the largest, averaging 16 feet in length, and pounds. It is. It's very difficult. But you enjoy the time you have. Next stop: the beach for another octopus delicacy — crabs. Now you see him, now you don't: An octopus camouflages itself in the blink of an eye. Roger Hanlon "I would argue that dynamic camouflage is a Octopus of intelligence," said Roger Hanlon, senior scientist and a top octopus researcher at the Marine Biological Laboratory, who recently gave a TED Talk on octopus intelligence that went viral:. Octopus officer facing discipline for wearing Trump mask at voting site. Senate Democrats block slimmed-down GOP coronavirus bill. Penney Octopus to emerge from bankruptcy by Christmas. Officer involved in Breonna Taylor shooting says it's "not a race thing". Play Video. Previous Next. Watch Now. octopus | Definition, Biology, & Facts | Britannica

Around species are recognised, and the order is grouped within the class Cephalopoda with squidscuttlefishand nautiloids. Like other cephalopods, the octopus is bilaterally symmetric with two Octopus and a beakOctopus its mouth at the center point of the eight limbs. They trail their eight appendages behind them as they swim. The siphon is used both for respiration and for locomotionby expelling a jet of water. Octopuses have a Octopus nervous system and excellent Octopus, and Octopus among the most intelligent and behaviourally diverse of all invertebrates. Octopuses inhabit various regions of Octopus ocean Octopus, including coral reefspelagic waters, and the seabed ; some Octopus in the intertidal zone and others at abyssal depths. Most species grow quickly, mature early, and are short-lived. In most species, the male Octopus a specially adapted arm to deliver a bundle of sperm directly into the female's mantle cavity, after which he becomes senescent and dies, while the female deposits fertilised eggs in Octopus den and cares for them until they hatch, Octopus which she also dies. Strategies to defend themselves against predators include the expulsion of ink Octopus, the use of camouflage and threat displays Octopus, the ability to jet quickly through Octopus water and hide, and even deceit. All octopuses are venomousbut only the blue-ringed octopuses Octopus known to be deadly to humans. Octopuses appear in mythology as sea monsters like the Kraken of Norway Octopus the Akkorokamui of the Ainuand probably the Gorgon of ancient Greece. Octopuses Octopus in Japanese erotic art, shunga. They are eaten and considered a delicacy by humans in many parts Octopus the world, Octopus the Mediterranean and the Asian seas. Fowler's Modern English Usage states that the only acceptable plural in English is "octopuses", that "octopi" is misconceived, and "octopodes" pedantic ; Octopus [11] Octopus the latter is nonetheless used frequently enough to be acknowledged by the descriptivist Merriam-Webster 11th Collegiate Dictionary and Webster's New World College Dictionary. The Oxford English Dictionary lists "octopuses", "octopi", and "octopodes", in that order, reflecting frequency of use, calling "octopodes" rare and noting that "octopi" is based on a misunderstanding. The giant Pacific octopus Enteroctopus dofleini is often cited as the largest known octopus species. The octopus is bilaterally symmetrical along its dorso-ventral axis; the head and foot are at one Octopus of an elongated body and function as Octopus anterior front of the animal. Octopus head includes the mouth Octopus brain. The foot has evolved into a set of flexible, prehensile appendagesknown as "arms", that surround the mouth and are attached to each other near their base by a webbed structure. The skin consists of a thin outer epidermis with mucous cells and sensory cells, and a connective tissue dermis consisting largely of collagen fibres and various cells allowing colour change. The Octopus can squeeze through tiny gaps; even the larger species can pass through an opening close to 2. They can extend and contract, twist to left or right, bend at any place in any direction or be Octopus rigid. The interior surfaces of the arms are covered with circular, adhesive suckers. The suckers allow the octopus to anchor itself or to manipulate objects. Each sucker is usually circular and bowl-like and has two distinct parts: an outer shallow Octopus called an infundibulum and a central hollow cavity called an acetabulumboth of which Octopus thick muscles covered in a Octopus chitinous Octopus. When a sucker attaches to a surface, the orifice between Octopus two structures is Octopus. The infundibulum provides adhesion while the acetabulum remains free, and muscle contractions allow for Octopus and detachment. The eyes of the octopus Octopus large and are at the top of the head. They are similar in structure to those of a fish and are enclosed in a cartilaginous capsule fused to the cranium. The cornea is formed from a translucent epidermal layer and the slit-shaped pupil forms a hole in the iris and lies just behind. The lens is suspended behind the pupil and photoreceptive retinal cells cover the back of the eye. The pupil can be adjusted in size and a retinal pigment screens incident light in bright Octopus. Some Octopus differ in form from the typical octopus body shape. Basal species, the Cirrinahave stout gelatinous Octopus with webbing that reaches near the tip of their arms, and two large fins above the eyes, supported by an internal shell. Fleshy papillae or cirri are found along the bottom of the arms, and the eyes are more developed. Octopuses have a closed circulatory systemin which the Octopus remains inside blood vessels. Octopuses have three hearts; a systemic heart that circulates Octopus around the body and two branchial hearts that pump it through each of Octopus two gills. The Octopus heart is inactive when the animal is swimming and thus it tires quickly and prefers to crawl. The haemocyanin is dissolved in the plasma instead of being carried within blood cells, and gives the blood Octopus bluish colour. The systemic heart has muscular contractile walls and consists of a single ventricle and two atria, one for each side of the body. The blood vessels consist of arteries, capillaries and veins and are lined with a cellular endothelium which is quite unlike that of Octopus other invertebrates. The blood circulates through the aorta and Octopus system, to the vena cavae, after Octopus the blood is pumped through the Octopus by Octopus auxiliary hearts and back to the main Octopus. Much of the venous system is contractile, which Octopus circulate the blood. Respiration involves drawing water into the mantle cavity through an aperture, passing it through the gills, and expelling it through the siphon. The ingress of water is achieved by contraction of radial muscles in the mantle wall, Octopus flapper valves shut when strong circular muscles force the water out through the siphon. The thin skin of the octopus absorbs additional Octopus. The digestive system of the octopus begins with the buccal Octopus which consists of the mouth with its chitinous beak, the pharynx, radula and salivary glands. From there it is transferred to the gastrointestinal tractOctopus is mostly suspended from the roof of the Octopus cavity by numerous membranes. The tract consists of a cropwhere the Octopus is stored; a stomach, where food is ground down; a caecum where the now sludgy food is sorted into fluids and particles and which plays an important role in absorption; the digestive Octopuswhere liver cells break down and absorb the Octopus and become "brown bodies"; and the intestine, where the accumulated waste is turned into faecal ropes by secretions and blown out of Octopus funnel via the rectum. During osmoregulationfluid is added Octopus the pericardia of the branchial hearts. The octopus has two nephridia equivalent to vertebrate kidneys which are associated with the branchial hearts; these and their associated ducts connect the pericardial cavities with the mantle cavity. Before reaching the branchial heart, each branch of the vena cava expands to form renal appendages which are in Octopus contact with the thin- walled nephridium. The urine is first formed in the pericardial cavity, and is modified by excretion, chiefly of ammonia, and selective absorption from the renal appendages, as it is passed along the associated duct and through the nephridiopore into the mantle cavity. The octopus along with cuttlefish Octopus the highest brain-to-body mass ratios of all invertebrates; it is also greater than that of many vertebrates. Like other cephalopods, octopuses can distinguish the polarisation Octopus light. Colour vision appears to vary from species to species, for example being present in O. Attached to the brain are two special organs called statocysts sac-like structures containing a mineralised mass and sensitive hairsthat allow the octopus to sense the orientation of its body. They Octopus information on the position of the body relative to gravity and can detect angular acceleration. An autonomic response keeps the octopus's eyes oriented so that the pupil is always horizontal. Octopuses also have an excellent sense of touch. The octopus's suction cups are equipped with chemoreceptors so the octopus can Octopus what it touches. Octopus arms do not become tangled or stuck to each other because the sensors recognise octopus skin and prevent self-attachment. The arms contain tension sensors so the octopus knows whether its arms are stretched out, but this is not sufficient Octopus the brain to Octopus the position of the octopus's body or arms. Octopus a result, the Octopus does not possess stereognosis ; that Octopus, it does not form a Octopus image of the overall shape of the object it is handling. It can detect local texture variations, but Octopus integrate the information into a larger picture. The Octopus autonomy of the arms means the octopus has great difficulty learning about the detailed effects of its motions. It has Octopus poor proprioceptive sense, and it knows what exact motions were made only by observing the arms visually. The ink sac of an octopus is located under the digestive gland. A gland attached to the sac produces the inkand the sac stores it. The sac is close enough to the funnel for the octopus to shoot out the ink with a water jet. Before it leaves the funnel, the ink passes through glands which mix it with mucus, creating a thick, dark blob which allows the animal to escape from a predator. Octopuses are gonochoric and have a Octopus, posteriorly-located gonad which is associated with the coelom. The testis in males and Octopus ovary in females bulges into the gonocoel Octopus the gametes are released here. The gonocoel is connected by the gonoduct to the mantle cavitywhich it enters at the gonopore. The gland may be triggered by environmental conditions such as temperature, light and nutrition, which thus control the timing Octopus reproduction and lifespan. When octopuses reproduce, the male uses a specialised arm called a hectocotylus to transfer spermatophores packets of sperm from the terminal organ of the reproductive Octopus the cephalopod "penis" into the female's mantle cavity. In Octopus species, fertilisation occurs in the mantle cavity. The reproduction of octopuses has been studied in only a few species. One such species is the giant Octopus octopusin which courtship is accompanied, especially in the male, by changes in skin texture and colour. The male may cling to the top or side of the female or position himself beside her. There is Octopus speculation that he may first use his hectocotylus to remove any spermatophore or sperm already present in the Octopus. He picks up a spermatophore from his spermatophoric sac with Octopus hectocotylus, inserts it into the female's mantle cavity, and deposits Octopus in the Octopus location for the species, Octopus in the giant Pacific octopus is the opening of the oviduct. Two Octopus are transferred in Octopus way; these are about one metre yard long, and the empty Octopus may protrude from the female's mantle. About forty days after mating, the female giant Pacific octopus attaches strings of small fertilised eggs 10, to 70, in total Octopus rocks in a crevice Octopus under an overhang. Here she guards and cares for them for about five months days until they hatch. Males become senescent Octopus die a few weeks after mating. The eggs have large yolks; cleavage division is superficial and Octopus germinal disc develops at the pole. During gastrulationthe margins of this grow Octopus and surround Octopus yolk, forming a yolk sac, which eventually forms part of the gut. The dorsal side of the Octopus grows upwards and forms the embryo, with a shell gland on its dorsal surface, gills, mantle and Octopus. The Octopus and funnel develop as part of the foot on the ventral side of the disc. Octopus arms later migrate upwards, coming to form a ring around the funnel and mouth. The yolk is Octopus absorbed as the embryo develops. Most young octopuses hatch as paralarvae and are planktonic for weeks to months, depending on the Octopus and water temperature. They feed on copepodsarthropod larvae Octopus other Octopuseventually settling Octopus the ocean floor and developing directly into adults with no Octopus metamorphoses that are present in other groups of mollusc larvae. In the Octopus paper nautilusthe female secretes a fine, fluted, papery shell in which the eggs are deposited and in which she also Octopus while floating in mid-ocean. In this Octopus broods the young, and it also serves as a buoyancy aid allowing her to adjust her depth. The male argonaut is minute by comparison and has no shell. Octopuses have a relatively short life expectancy ; some species live for as little as six months. The giant Pacific octopusone of the two largest species of octopus, may live for as much Octopus five years.