95 Fun Facts About Octopus

To which class of molluscs do octopuses belong, along with squid, cuttlefish and nautiluses?

Cephalopoda is the mollusc class of octopuses, squid, cuttlefish and nautiluses; apart from the nautiluses, its living members have tucked the ancestral shell inside the body or lost it altogether.

How many hearts does an octopus have?

An octopus has three hearts: two branchial hearts push blood through the gills and one systemic heart sends it round the body, which keeps the pressure high enough to move its thick blood.

Which copper-based protein carries oxygen in octopus blood?

Haemocyanin carries oxygen on copper where our haemoglobin uses iron, and it does the job better than haemoglobin in cold, low-oxygen water, which suits life in the ocean.

What fraction of an octopus's neurons are located in its arms rather than its brain?

About two-thirds of an octopus's neurons lie in its arms rather than its central brain, which is why a severed arm can keep moving and reacting to touch for a while.

Which is the only kind of octopus known to be deadly to humans?

Blue-ringed octopuses, genus Hapalochlaena, are the only octopuses known to have killed people; every octopus is venomous, but no antivenom exists for a blue-ringed bite.

Which toxin, also the poison of pufferfish, lets the deadliest octopus paralyse its victims?

Tetrodotoxin, made by bacteria in the octopus's salivary glands, blocks the sodium channels that nerves need to fire; victims kept breathing by machine through the first day usually recover fully.

Which species is usually cited as the largest octopus?

The giant Pacific octopus is the species usually called the largest, with an arm span that often passes 4 metres, yet it hatches from an egg the size of a grain of rice.

Which octopus, weighing under a gram as an adult, is the smallest known species?

The star-sucker pygmy octopus of the western Pacific is small enough to sit on a fingertip; as its name suggests, males carry fringed, star-shaped suckers.

An octopus is said to squeeze through any hole no smaller than which part of its body?

Its beak, a parrot-like bill, is often said to be the limit: it is the only hard part of an octopus, and the rest is boneless soft tissue that can pour through a gap after it.

Georges Cuvier mistook a detached mating arm of a male octopus for what?

A parasitic worm, he decided, and named it Hectocotylus as a new species; the name stuck to the arm after Japetus Steenstrup showed in 1856 that males use it to pass sperm.

What happens to a male octopus after mating?

He becomes senescent and dies: after mating, a male octopus stops eating, weakens and is dead within a few months, while the female dies after brooding her eggs.

Which deep-sea animal with eight webbed arms is the octopuses' closest living relative?

The vampire squid is neither a squid nor a blood-drinker: it shares the superorder Octopodiformes with the octopuses and feeds on 'marine snow', the debris drifting down from the waters above.

How long does a common octopus usually live?

One to two years is the usual lifespan of a common octopus, and even the biggest species manage about five; yet one deep-sea mother off California was watched guarding a single clutch of eggs for 53 months.

Removing which glands lets a brooding female octopus start eating again and live much longer?

The optic glands release the signals behind a mother octopus's fatal fast; in Jerome Wodinsky's 1977 experiment, females without them stopped brooding, fed again and lived far longer.

What is the main pigment in octopus ink?

Melanin, the same pigment that darkens human skin and hair, is the main pigment in octopus ink; the ink mixes with mucus and leaves the funnel as a dark blob that works as a decoy or smokescreen.

Which specialised skin cells give an octopus its rapid camouflage?

Chromatophores are elastic pigment sacs in the skin, holding yellow, orange, red, brown or black, that muscles stretch open or shut in an instant; iridophores and leucophores beneath add shimmer and white.

What is the octopus display called in which waves of dark colour ripple across the body?

The passing cloud is a dark wave that sweeps over the body and arms like a cloud's shadow; octopuses often show it when a hunted crab freezes, so it is thought to startle prey into moving.

When damselfish attack it, the mimic octopus has been seen impersonating which of their predators?

A sea snake, banded and venomous, is the disguise it picks for damselfish; the mimic octopus, discovered in Indonesia in 1998, also poses as lionfish and sole, apparently matching the act to the threat.

The veined octopus is famous for collecting and carrying what to build a shelter?

Discarded coconut shells are dug up, rinsed with jets of water and carried off under the body in an awkward 'stilt walk', then put back together as a shelter when needed: a celebrated case of tool use.

What is an octopus's fastest way of moving?

Jet propulsion shoots water from the mantle out through the funnel to rocket the octopus away; it is costly, so octopuses save it for escapes and mostly crawl.

What extra sense do an octopus's suckers give its arms?

Chemoreceptors in the suckers let an octopus taste whatever it touches; a chemical in its own skin switches off the suckers' grip, which is what stops its arms sticking to one another.

Which organs in an octopus's head detect gravity and acceleration, and possibly sound?

Statocysts are paired sacs in which a tiny stone rests on sensory hairs, so its shifting weight signals gravity and acceleration; with them the common octopus can also detect sounds of roughly 400 to 1,000 Hz.

Octopuses sometimes hunt cooperatively with fish, and keep their partners in line by doing what?

Punching them: a day octopus whips out one arm in an explosive jab that knocks a fish out of position, and a 2024 study found blacktip groupers, which hang back and freeload, took the most hits.

Unlike nearly all other octopuses, the larger Pacific striped octopus has been found doing what?

Living in groups of up to 40, in dens about a metre apart, was reported by Arcadio Rodaniche decades ago; a team confirmed much of the account only after keeping live animals from 2012.

As of a 2020 study, which octopus is the deepest ever filmed, nearly 7,000 metres down in the Indian Ocean?

Dumbo octopuses took the record when a camera lander caught one 6,957 metres down in the Java Trench, a sighting that suggests cephalopods could live on about 99% of the world's seafloor.

The dumbo octopus is named for which body part, which resembles the ears of Disney's flying elephant?

Its fins, one on each side of the mantle above the eyes, flap to row the dumbo along; cirrate octopuses like it swim this way and usually have no ink sac.

Which habitat has no known octopus species at all?

Fresh water has no octopus, nor any other cephalopod; yet octopuses live in the frigid seas off Antarctica and one species, Vulcanoctopus hydrothermalis, beside deep hydrothermal vents.

The female argonaut, an open-ocean octopus, rides in a thin white 'shell' that is really what?

The argonaut's 'shell' is a secreted egg case: the female makes it herself, broods her eggs inside and gulps air into it at the surface to control her buoyancy.

Which plural treats 'octopus' as a Latin word, though it actually comes from Greek?

Octopi copies Latin plurals such as cacti, but octopus comes from Greek, where the plural would be octopodes; dictionaries accept octopi anyway, though octopuses is the more common form.

The word 'octopus' comes from Greek words meaning what?

Eight foot is the literal sense of the Greek oktopous, from okto, eight, and pous, foot; the same pous ends platypus, 'flat-footed', which is why the two animals share half a name.

An octopus's brain is shaped like a doughnut because which tube runs straight through the middle of it?

The oesophagus passes through the ring-shaped brain on its way to the stomach, so every meal an octopus swallows travels through the middle of its head.

Which process do octopuses and squid use far more than other animals to alter proteins, mostly in their nervous system?

RNA editing lets these cephalopods rewrite their genetic messages at tens of thousands of sites without touching the genes themselves; the price is that the DNA around those sites evolves unusually slowly.

Which ancient Greek described the octopus's colour change and mating arm in Historia animalium?

Aristotle recorded the octopus's colour change and mating arm in Historia animalium, yet he also called it 'a stupid creature' because it would swim up to a hand lowered into the water.

Which Norwegian sea monster of legend is conceived as octopus-like?

The kraken of Scandinavian sea lore was said to drag whole ships under, and in 1801 the French naturalist Pierre Denys de Montfort drew a colossal octopus seizing one; stranded giant squid probably fed the legend.

Which Japanese artist made the 1814 shunga print The Dream of the Fisherman's Wife?

Katsushika Hokusai, best known for The Great Wave, made The Dream of the Fisherman's Wife in 1814 for his shunga book Kinoe no Komatsu; it later inspired a 1903 drawing by Picasso.

A battle with an octopus features in which Victor Hugo novel of 1866?

Toilers of the Sea, Victor Hugo's 1866 novel set on Guernsey, has its hero Gilliatt battle a giant octopus, a scene that made the word pieuvre famous in French.

Paul the Octopus became a celebrity in 2010 for predicting winners at which sporting event?

The FIFA World Cup made Paul famous: at an aquarium in Germany he chose a mussel from one of two boxes marked with flags, and all eight matches put to him went the way he picked.

Which Korean dish serves freshly cut octopus arms that are still wriggling on the plate?

San-nakji is small octopus chopped and served at once, so the pieces still squirm by reflex; the suckers keep their grip and can lodge in a diner's throat, a real choking risk.

Inky the octopus made headlines in 2016 by escaping from his New Zealand aquarium how?

Down a drainpipe to the sea: Inky is thought to have slipped through a gap in his tank lid at the National Aquarium of New Zealand, crossed the floor and squeezed into a 50-metre drain.

Which country's animal-testing law covered only one invertebrate, the common octopus, until an EU directive widened it?

The United Kingdom's Animals (Scientific Procedures) Act named the common octopus a protected animal in 1993; the EU directive that widened it to all cephalopods cited scientific evidence that they can feel pain and suffer.

Philosopher Peter Godfrey-Smith called octopuses and their relatives probably the closest we will come to meeting what?

An intelligent alien, he wrote in Other Minds, because our last common ancestor with the octopus was a worm-like creature some 600 million years ago, so its mind evolved quite separately from ours.

Which Bronze Age civilisation's Marine Style pottery, around 1500 BCE, featured sprawling octopuses?

The Minoans of Crete covered whole pots with octopuses, fish and dolphins in the Marine Style, perhaps inspired by frescoes; Mycenaean Greek potters went on painting octopuses on jars of about 1200 to 1100 BCE.

Roughly how many octopus species make up the order Octopoda?

About 300 living octopus species are known, from reefs to the deep sea, but their past is hazy: a body with no shell and almost no hard parts rarely leaves a fossil.

As of 2020, what was the live mass of the heaviest scientifically documented octopus?

The heaviest scientifically documented octopus weighed 71 kg, a specimen of the largest species; adults of that species usually weigh 10 to 50 kg, and a 600 lb claim was never verified.

What colour is an octopus's blood when it is carrying oxygen?

Blue, because the oxygen carrier in octopus blood is built around copper, not the iron that makes ours red; drained of oxygen, the blood turns clear.

Which Beatle wrote Octopus's Garden after a boat trip off Sardinia in 1968?

Ringo Starr got the idea on Peter Sellers's boat, where the captain told him octopuses gather stones and shiny objects to build gardens. The song appeared on Abbey Road.

Doctor Octopus, a scientist with four mechanical arms, is a classic enemy of which superhero?

Spider-Man first faced Doctor Octopus in 1963, in a story by Stan Lee and Steve Ditko, and the villain became known to fans as Doc Ock.

Paul the Octopus made his famous predictions from a Sea Life aquarium in which country?

Germany was home to Paul, who lived in Oberhausen and made each pick by choosing between two food boxes, each decorated with a flag.

Inky the octopus slipped out of his tank and down a drainpipe to the sea in which country?

New Zealand's National Aquarium in Napier lost Inky in 2016, when he crossed the floor at night and squeezed down a 50-metre pipe to the ocean. He was never found.

Which Pirates of the Caribbean villain, played by Bill Nighy, has a beard of octopus-like tentacles?

Davy Jones, captain of the Flying Dutchman, is completely computer-generated, built over Bill Nighy's motion-capture performance.

Fans of which NHL team have thrown octopuses onto the ice during the playoffs since 1952?

Detroit Red Wings fans took it up after two brothers hurled an octopus in 1952, its eight arms standing for the eight playoff wins then needed to lift the Stanley Cup.

In a 2018 experiment, normally solitary octopuses became more sociable after a dose of which drug?

MDMA, better known as ecstasy, acts on a serotonin pathway, and the result suggests social behaviour has a shared genetic basis across much of the animal world.

A ten-armed fossil relative of the octopus, dug up in Montana, was named after which US president?

Joe Biden is honoured in the name Syllipsimopodi bideni, chosen partly to raise awareness of his climate policies. The fossil was found in 1988 and given to the Royal Ontario Museum.

The plural 'octopi' wrongly treats the word octopus as if it came from which language?

Latin nouns ending in -us often take -i, but octopus comes from Greek, so the Oxford English Dictionary notes that octopi rests on a misunderstanding.

Hank, a grumpy octopus who has lost one arm, helps the heroine of which Pixar film?

Finding Dory calls Hank a septopus because he is one arm short, and Ed O'Neill voices the grumpy hero.

Squidward Tentacles, an octopus despite his name, plays which instrument in SpongeBob SquarePants?

Clarinet is Squidward's great passion, though he has no real talent for it. His creator drew him as an octopus because he liked the species' large head.

Ursula, the sea witch with an octopus's lower body, is the villain of which Disney film?

The Little Mermaid gave Ursula six tentacles rather than eight to save money on animation, and her look was inspired by the drag performer Divine.

The Oscar-winning documentary My Octopus Teacher was filmed in a kelp forest off which country?

South Africa's False Bay, near Cape Town, is where filmmaker Craig Foster spent a year free-diving to visit one wild octopus.

Takoyaki, battered balls filled with diced octopus, were first popularised in which Japanese city?

Osaka street vendor Tomekichi Endo is credited with inventing takoyaki in 1935, cooking the batter in a special moulded pan.

In the 1955 monster film It Came from Beneath the Sea, a giant octopus attacks which landmark?

Golden Gate Bridge scenes show a monster with only six arms, because animator Ray Harryhausen's budget would not stretch to eight. He nicknamed it the sixtopus.

Which cardiac condition is named takotsubo after a Japanese pot for trapping octopuses?

Broken heart syndrome makes the left ventricle bulge into the shape of the round jar, usually after a severe emotional or physical shock.

Octopolis and Octlantis, two settlements built by gloomy octopuses, lie in a bay off which country?

Australia's Jervis Bay holds both sites, where the animals burrow their dens into a bed made mostly of scallop shells.

Blanket octopuses rip stinging tentacles from which venomous sea creature to use as weapons?

Portuguese man o' war venom does not harm blanket octopuses, so males and young females tear off the tentacles and wield them in attack and defence.

Resting octopuses pass through a twitchy 'active' stage that scientists liken to which human state?

REM sleep is the nearest human match: the octopus stage lasts about a minute, with moving eyes, a twitching body and faster breathing.

In which novel does Marcellus, an aquarium octopus, befriend a widowed cleaner named Tova?

Remarkably Bright Creatures, Shelby Van Pelt's 2022 novel, follows Tova as she catches Marcellus slipping out of his enclosure again and again.

Which monstrous H. P. Lovecraft creation combines an octopus-like head with features of a dragon?

Cthulhu first appeared in a 1928 story in the pulp magazine Weird Tales, as a gigantic being worshipped by cultists.

A Florida carcass of 1896, once hailed as a giant octopus, proved to be the remains of which animal?

A whale, most likely a sperm whale, left the St. Augustine Monster: later tests showed the blob was a mass of collagen from blubber.

Which islands' creation myth casts the octopus as the lone survivor of an earlier age of the world?

Hawaii's creation chant, the Kumulipo, has a recurring verse that scholars read as the octopus outliving a previous age of existence.

Frank Norris's 1901 novel The Octopus pits wheat growers against which powerful industry?

The railroads battle the ranchers in a story that Norris based on the Mussel Slough Tragedy, a bloody 1880 clash between ranchers and lawmen acting for a rail company.

Gloomy octopuses have been filmed doing what to annoying neighbours on the seabed?

Throwing silt at them, along with shells and algae, is done with a blast of water from the siphon. Throwing of any kind is rare among animals.

Henry the Octopus and Dorothy the Dinosaur are costumed friends of which children's music group?

The Wiggles built their stage act around Henry, Dorothy, Wags the Dog and the friendly pirate Captain Feathersword.

The Pacific Northwest tree octopus, a 1998 internet hoax, supposedly lived in which woodland?

Olympic National Forest was the creature's supposed home on a spoof website that schools now use to teach children to doubt what they read online.

Otto, an aquarium octopus, made headlines by squirting water at an overhead lamp to cause what?

A short circuit was Otto's trick on more than one occasion at the Sea Star Aquarium in Coburg, where he also juggled hermit crabs and struck the glass with a rock.

Octocat, a cat with octopus-like arms, is the mascot of which code-hosting website?

GitHub picked the character from stock clip art by designer Simon Oxley, who had called it Octopuss, and the mascot now goes by Mona.

Akkorokamui, the giant octopus of Ainu folklore, is said to lurk in a bay of which Japanese island?

Hokkaido's Uchiura Bay is the monster's home, and legend held that it was big enough to swallow a whole ship.

The World Octopus Wrestling Championships of the 1960s were held in which body of water?

Puget Sound drew 111 divers to the 1963 contest, where the aim was to grapple a large octopus in shallow water and drag it to the surface.

Which octopus became the first to have its genome fully sequenced, in 2015?

California two-spot octopuses take their name from the false blue eyespot that sits beneath each real eye.

Which small octopus, prized by underwater photographers, has white markings unique to each animal?

Wunderpus photogenicus is its fitting scientific name, and the pale pattern stands out against a rusty brown body.

The deep-sea octopus Stauroteuthis syrtensis is unusual because its suckers can do what?

Glow in the dark is right: about 40 modified suckers along each arm give off a blue-green light, a talent very few octopuses share.

What name do biologists give the pile of dead and uneaten food outside an octopus's den?

A midden is more than a rubbish heap: the leftovers can attract scavengers such as fish and echinoderms to the den.

Which naturalist wrote The Soul of an Octopus, a finalist for the 2015 National Book Award?

Sy Montgomery's book, subtitled A Surprising Exploration into the Wonder of Consciousness, also reached The New York Times Best Seller list.

The lusca, a legendary half-shark, half-octopus, is said to haunt the blue holes of which country?

The Bahamas island of Andros is the legend's home, and other accounts make the lusca a giant octopus or a giant cuttlefish.

In Māori tradition, which navigator pursued and killed the monstrous octopus Te Wheke-a-Muturangi?

Kupe destroyed the beast in Tory Channel in one telling, while another version places the kill at Pātea.

Octobot, a soft autonomous robot shaped like a small octopus, was built at which university?

Harvard researchers 3D-printed the body from silicone gel and powered it with hydrogen peroxide, so it needs no battery.

Vulcanoctopus, a small octopus of the East Pacific Rise, lives only around which seafloor features?

Hydrothermal vents suit this species, which lives beside colonies of tube worms where hot water carries plumes of toxic metal sulfides.

The seven-arm octopus, one of the two largest known species, has been filmed catching which animals?

Jellyfish may serve it twice over: evidence suggests the octopus not only feeds on them but also uses them for protection.

In which 2003 South Korean thriller does the lead actor eat a real live octopus on camera?

Oldboy used no computer effects for the scene, and four octopuses were needed to film it.

Which actor voiced Dave, the vengeful octopus scientist in the 2014 film Penguins of Madagascar?

John Malkovich's Dave was a zoo attraction until the penguins upstaged him, so he disguises himself as a human scientist to take revenge.

Which actor narrated National Geographic's 2024 documentary series Secrets of the Octopus?

Paul Rudd narrates the three episodes, which James Cameron executive produced as a follow-up to his series on whales and elephants.

Octolings, humanoids who can turn into octopuses, are playable characters in which Nintendo series?

Splatoon lets Octolings and their squid counterparts, the Inklings, switch at will between a humanoid shape and a sea-creature shape that swims through ink.

A 2013 US spy-satellite launch made news for a mission logo of a giant octopus gripping what?

The Earth sat wrapped in the creature's arms on the NROL-39 patch, which was widely criticised because it followed that year's surveillance disclosures.

Which playful species name was floated in 2015 for a California flapjack octopus then thought to be new to science?

Opisthoteuthis adorabilis was the informal label for flapjack octopuses that Monterey Bay Aquarium Research Institute scientists kept and studied in 2015. The name was never formally published.

Which ocean explorer co-wrote the 1973 book Octopus and Squid: The Soft Intelligence?

Jacques Cousteau wrote it with Philippe Diolé as one volume of an eight-book series on his undersea discoveries, alongside titles on sharks and whales.

In scuba diving, 'octopus' is the nickname for which piece of emergency equipment?

A spare demand valve earns the nickname from the extra hose it adds, and it is carried mainly so a dive buddy can breathe from it in an emergency.

The octopus stinkhorn, which hatches from a white 'egg' into red arms, is what kind of organism?

A fungus also known as devil's fingers, it unfurls four to six arms covered in a dark-olive layer that carries its spores.