Octopus Characteristics, History and Human Food

Home | Category: Cephalopods (Octopus and Squid)


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Common octopus (Octopus vulgaris)

Octopuses live in all the worlds oceans, from the poles to the tropics. They can survive the frigid oceans around Antarctica and have been found at depths of 6,975 meters (22,825 feet). The Minoans painted octopuses on vases 3,500 years ago and the Beatles sang about them on “ Abbey Road”. People from all over the world, particularly in Asia and the Mediterranean, enjoy eating them. [Sources: Natalie Angier, New York Times, August 11, 1998; Gilbert L. Voss Ph.D., National Geographic, December 1971]

Octopuses (Octopi) tend to be reclusive and hard to find. Because they are so good at camouflage it can be hard to see them even when they are right in front of you. Octopuses are mollusks that have completely lost their shell, although one species, the argonaut, creates a paper-thin replica of a nautilus shell from one of its arm. It uses the shell as a receptacle for its eggs. Octopuses generally mate once and waste away and die soon after that. Many species live a little over a year. It is rare for an octopus to live more than three years.

There are around 300 species of Octopods. They range in size from the 2.5 centimeters (one-inch) star-sucker pygmy octopus and 28 gram (one-ounce) Atlantic pygmy octopus, Octopus joubini, to the 9-meter (30-foot) the giant Pacific octopus, Enteroctopus dofleini. Known for their otherworldly appearance and characteristics, they have bulbous heads, large eyes, three hearts, blue blood, ink squirting capabilities, doughnut-shaped brains, and beak-like jaws. According to Reuters: They are adept at camouflage — changing colors and even textures to mimic their surroundings — and can maneuver their bodies into tiny cracks and crevices. They also are capable of tool use and problem-solving. [Source: Will Dunham, Reuters, March 9, 2022]

The giant Pacific octopus can reach a length of around 15 feet long (13 foot long tentacles and a head the size of a football) and weigh around 100 pounds. Typically though they weigh about 40 pounds. Each of its eight arms are about five feet long and have 2000 suckers.The smallest are around an inch long when fully grown. Deep seas octopus found at depths of around 3,000 feet have suckers that no longer suck but instead glow in the dark. The glowing suckers are used to signal each other and attract prey.

Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se ; Encyclopedia of Life eol.org ; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems

Book: “Learning From the Octopus: How Secrets from Nature Can Help Us Fight Terrorist Attacks, Natural Disasters, and Disease” by Rafe Sagarin, Basic Book, 2012.


Common octopus (Octopus vulgaris)
Octopuses, squid and cuttlefish are cephalopods, a class of mollusks whose name means "head-footed." There are two subclasses of Cephalopoda: 1) chambered nautiluses, with external shells and anatomy that has remained virtually unchanged for 450 million years; and 2) coleoidea, which includes octopuses, squids and cuttlefish. The latter are soft, fleshy mollusks with their shells inside their bodies instead of outside as is the case with most mollusks.

Cephalopods are common food sources in many counties, particularly in Asia. They reproduce quickly which means that even though two million metric tons of them are caught every year, they are not in danger of being overfished. In the past they were often caught with drift nets, which are now banned not because they caught too many squid but because they caught other animals like dolphins and sharks.

Cephalopods are regarded as more developed and sophisticated than mollusks like snails, clams and oysters. In fact they are considered the most advanced and developed invertebrates (animals without backbones). They have the largest brains and nervous systems of any invertebrate and their brains are much bigger in relationship to their bodies than those of fish. Most cephalopods grow quickly, mate once and die. Most live no more than 18 months.

Oldest Known Octopus Lived 328 Million Years Ago

Octopuses are cephalopods, a marine invertebrate group dating back to roughly 530 million years ago and distinguished by having arms or tentacles. Cephalopods today also include squids, cuttlefishes and nautiluses. Vampyropods (Octopodiformes) make up the superorder that includes today's octopuses. See Cephalopods

In March 2022, scientists announced they had discovered the oldest known ancestor of octopuses — which lived approximately 328 million years ago — based on fossil of the that age unearthed in Montana. The discovery pushed back by 82 million years the origins of vampyropods, meaning that octopuses originated before the era of dinosaurs Associated Press reported:. The 4.7-inch (12-centimeter) fossil had 10 limbs — modern octopuses have eight — each with two rows of suckers. It probably lived in a shallow, tropical ocean bay. “It's very rare to find soft tissue fossils, except in a few places,” said Mike Vecchione, a Smithsonian National Museum of Natural History zoologist.“This is a very exciting finding. It pushes back the ancestry much farther than previously known." [Source: Christina Larson, Associated Press, March 9, 2022]

The specimen was discovered in Montana's Bear Gulch limestone formation and donated to the Royal Ontario Museum in Canada in 1988. For decades, the fossil sat overlooked in a drawer while scientists studied fossil sharks and other finds from the site. But then paleontologists noticed the 10 tiny limbs encased in limestone. The well-preserved fossil also “shows some evidence of an ink sac,” probably used to squirt out a dark liquid cloak to help to evade predators, just like modern octopuses, said Christopher Whalen, an American Museum of Natural History paleontologist and co-author of the study published in early March 2022 in the journal Nature Communications.

Proteroctopus ribeti had six legs and lived in the Middle Jurassic Period 174.1 million to 163.5 million years ago

The creature, a vampyropod, was likely the ancestor of both modern octopuses and vampire squid, a confusingly named marine critter that’s much closer to an octopus than a squid. Previously, the “oldest known definitive” vampyropod was from around 240 million years ago, the authors said. The scientists named the fossil Syllipsimopodi bideni, after U.S. President Joe Biden. Whether or not having an ancient octopus — or vampire squid — bearing your name is actually a compliment, the scientists say they intended admiration for the president's science and research priorities. The species also happened to be identified close to the inauguration of Biden as the U.S. 46th president.

Not all scientists believe the Syllipsimopodi bideni is a new species. According to The New York Times, some paleontologists like Christian Klug of the University of Zurich believe it is a known species of ancient cephalopods — a Gordoniconus beargulchensis. He also told The New York Times that Syllipsimopodi bideni matches the size, age, and proportions of another species. Dr. Whalen says said there are enough differences between G. beargulchensis and the new vampyropod to make the new species call. Without proper chemical analysis, which is probably be impossible, it may be hard to say without a doubt. [Source: Joshua Hawkins, BGR, March 10, 2022]

Oldest Known Octopus Had Ten Arms Instead of Eight

Syllipsimopodi bideni had 10 arms, with two twice as long as the other eight, as well as a torpedo-shaped body that gave it squid-like appearance though it was not closely related to squids, which appeared much later. It also is the oldest-known creature with suckers, which enable the arms to better grasp prey and other objects. "The fossil greatly changes our understanding of how octopuses evolved and indicates that the earliest members of the group superficially resembled living squids," said Whalen, a postdoctoral fellow at the American Museum of Natural History in New York and Yale University. [Source: Will Dunham, Reuters, March 9, 2022]

Reuters reported: The very word octopus means eight feet. Syllipsimopodi represents the only member of the octopus lineage with 10 arms, meaning two were lost in later evolution. There are numerous similar examples in the history of life on Earth — such as the reduction in the number of digits seen in meat-eating dinosaurs or horses. Today's vampire squids have eight arms and two thin filaments that scientists long have considered vestiges of former arms. Octopuses do not have these vestigial filaments. "Syllipsimopodi is the first fossil to demonstrate that, yes, vampyropods did ancestrally possess 10 arms as had been predicted," Whalen said.

Two of Syllipsimopodi's arms were about 1-1/2 inches long and the other eight half that length, a squid-like configuration. "Capture of prey is facilitated by the two longer tentacles with the eight shorter arms helping to manipulate the prey and transport it to the beak," said study co-author Neil Landman, an American Museum of Natural History invertebrate paleontologist.

Syllipsimopodi prowled the warm waters of a tropical bay — Montana at the time was situated close to the equator. It may have been a mid-level predator, eating smaller invertebrates. Syllipsimopodi lived during the Carboniferous Period, a time of important evolutionary changes in other marine life that included the appearance of more modern-looking fishes. "Syllipsimopodi" means "prehensile foot" — its arms are an evolutionary modification of the foot of mollusks.

Octopus Characteristics

Octopuses are cold blooded (ectothermic, use heat from the environment and adapt their behavior to regulate body temperature). They have a soft body that can rapidly change color and texture . As invertebrates they have no skeleton. Their bodies are amazing compressible and can squeeze through openings no bigger than one of their eyeballs. Its incredible flexibility results from its musculature, which consists of fibers that run in three directions, permitting it to change shape. [Source: Kelly Ray, Animal Diversity Web (ADW) /=]

Octopuses are mollusks. Like all mollusks, they possesses a mantle. However, the mantle is fused with the cephalized head on the dorsal side. The appendage at the top of their arms is not their head. It is actually a mantle that stores their organs. The true head is small thing around the eyes. The “head” (body with the eyes on it) is soft and rubbery and pulses like bellows as its siphon system sucks water in through its gills so it can breath. An octopus eye is very similar to a human eye. They have pupils that dilate and contract and are often used to test new eye drugs. They also have the most complex brain of any mollusk.

According to Animal Diversity Web: The central nervous system of the octopus is the largest and most complex in the invertebrate world, rivaling that of many vertebrates, including mammals. Also analogous with the vertebrates, members of Octopuses possess two large, complex eyes that are camera-like in structure, and their vision is acute. Although Octopuses has a closed circulatory system like higher animals as well, the blood is a poor carrier of oxygen. As a result, Octopuses tires easily. To stay alive, it relies on a system involving three hearts and permanently high blood pressure.

Many species of octopus change color. Their "skin" is equipped with chromatophores, which are pigment cells that an animal can expand or contract by muscular action. These cells vary in color, and as the animals expands some or contracts others, its color changes. Using pigment sacs controlled by the their nervous system and well-developed brain, octopuses can change color to express different emotions, deter predators or attract prey. To scare off predators one species displays a zebra strip pattern of brown and white. Another species turns bright red whenever a crab approaches in what seems like an attempt to confuse the prey. Other species can change from blue-green to water and yet others can be different colors on different sides of their body.

Octopus Tentacles

tentacles of the giant Pacific octopus

A major distinguishing feature of octopuses is their eight muscular arms, which radiate out from the body around the beak-like jaws. According to Animal Diversity Web: In males, the third right arm is modified into a hectocotylus for mating. Each arm bears two rows of whitish suckers that can move independently. Each sucker may have 10,000 neurons to handle both taste and touch, and an octopus has thousands of suckers. Octopuses has an ability to regenerate an injured or lost arm. It usually takes about six weeks for an arm to regenerate. It has been found that, along with arms,Octopuses can even regenerate part of an eye that is damaged. [Source: Kelly Ray, Animal Diversity Web (ADW)]

Most octopus have around 1,200 suckers on each of its eight arms. There are examples of octopus being born with six legs. Because they have no skeleton to support their body they have tough tendons which help to support and anchor the muscles. The tendons make the muscles much tougher than those found in bony fish which is why octopus meat has a rubbery texture to those who eat it.

Octopuses have a brain-like organ in each on of their tentacles. In his book “The Story of Sushi”, Trevor Corson wrote: “These ganglai receive a single command from the primary brain’such as “grab a crab” — and then execute an entire subroutine of action independent of the primary brain’s control.

Octopus Dexterity

Octopus tentacles require their own brains because their movements are so complex. Lacking a skeletal structure, each tentacle is of infinite degrees and directions of movement.” An octopus is skillful enough to pass a pebble down its arm from one sucker to the next and nimble enough to grasp 25 crabs at one time and eat them one by one. Their dexterity is so admired by scientists that they have used them as models for robots.

Octopuses are relatively easy to keep in captivity, much easier than squid but it sometimes difficult to keep them confined to their tanks. "An octopus can pour its boneless body through unbelievable small apertures," biologist Gilbert L. Voss told National Geographic. “In our laboratory...octopuses flee their tanks...even when tops are fastened securely. [They] have escaped from covered tin cans, securely tied wooden boxes — even from steel strongboxes."

An octopus with foot-long tentacles and a tennis-ball-size body escaped from a Coke bottle by squeezing through the half inch opening by first running its tentacles through the aperture one by one and then squeezing its head through like compressed a rubber ball. The process takes about two minutes. Octopus have also been observed removing a rubber stopper from a bottle to get at a shrimp inside.

Octopuses Have a Secret Sense That Keep Their Eight Arms Out of Trouble

20120518-Octopus3.jpg Richard Sima wrote in the New York Times: Though it is well-known for its many arms, the octopus does not seem to know where those eight appendages are most of the time. “In the octopus, you have no bones and no joints, and every point in its arm can go to every direction that you can think about,” said Nir Nesher, a senior lecturer in marine sciences at the Ruppin Academic Center in Israel. [Source: Richard Sima, New York Times, February 21, 5, 2021]

So how does the octopus keep all those wiggly, sucker-covered limbs out of trouble? According to a study published last month in The Journal of Experimental Biology by Nesher and his colleagues, the octopus’s arms can sense and respond to light — even when the octopus cannot see it with the eyes on its head. This light-sensing ability may help the cephalopods keep their arms concealed from other animals that could mistake the tip of an arm for a marine worm or some other kind of meal.

Itamar Katz, one of the study’s authors, first noticed the light-detecting powers while studying a different phenomenon: how light causes the octopus’s skin to change color. With Nesher and Tal Shomrat, another author, Katz saw that shining light on an arm caused the octopus to withdraw it, even when the creature was sleeping. Further experiments showed that the arms would avoid the light in situations when the octopus could not see it with its eyes. Even when the octopuses reached an arm out of a small opening on an opaque, covered aquarium for food, the arm would quickly retract when light was shined on it 84 percent of the time. This was a surprise, as if the octopus “can see the light through the arm; it can feel the light through the arm,” Nesher said. “They don’t need the eye for that.”

However, it is still a mystery how an octopus’s arms can detect light, let alone respond to it. Surgical experiments did provide some clues. The arm stopped retracting from the light when it was separated from the body or when the octopus was anesthetized. Though the behavioral response did not require sight, it still required the brain to be intact.

Octopus Movement

According to Animal Diversity Web: Because of its unusual design, octopuses has perfected many different modes of locomotion. Octopuses can employ the arms for grasping or as locomotive devices, enabling it to crawl along the bottom or, in rare instances, out of the water. Its usual direction of swimming is "backwards" (i.e., away from the tips of the arms), with water being ejected from the funnel at the base of the arms propelling the animals through the water. However, they can also funnel in the opposite direction and swim with their arm tips pointing forwards. [Source: Kelly Ray, Animal Diversity Web (ADW) /=]

While swimming, its preferred attack posture is to parachute gently down with all eight arms outstretched and envelop its prey with its arms. Octopuses also crawls over reefs, probing with it arms for hidden prey. However, this creature is not aggressive and will tend to hide or flee if disturbed; it has the reputation of only biting if provoked. /=\

Although octopuses are equipped for swimming , many prefer to crawl along the sea floor rather than actively swim. Among some species when they swim one of their three hearts — the systemic heart — stops beating.

Octopuses and Humans

Octopuses — as well as their cephalopod mates, cuttlefish and squid — are an important food sources and significant source of protein for many people, especially in Japan, Korea, East Asia and the Mediterranean.. About 3.3 million tonnes (3.6 million short tons), worth US$6 billion, are commercially fished, annually. For thousands of years, humans have caught octopuses using lures, spears, pot traps, nets, and bare hands.

Japanese fisherman catch octopus in earthen jars that are tied together with ropes and dropped to the bottom of the sea. Octopus's apparently like dark places to crawl into the jars and hide so not bait or lid is necessary and the animals will stay in the jars even when they are hauled aboard a boat. On a good day about half on the jars that a fisherman has submerged will contain four or five pound octopuses. If an octopus is found with a leg missing it usually means it has eaten itself to stave off starvation. [Source: Bart McDowell, National Geographic, March 1974]

Vessels used in octopus fishing lower the pots to the sea floor and anchor them. Octopuses are always on the lookout for new home and they crawl into the pots with little hesitation. When fisherman drags up the pot the octopuses rarely try to escape. The technique does not even require bait. Potting octopus has changed little over millennia. The pots were traditionally made of terracotta. Now, most are plastic. The ancient Greeks used octopus pots that were not so different than the ones used today by modern fisherman in Spain, Greece and Japan. [Source: Abraham Rinquist, Listverse, September 16, 2016]

Octopus as Food in Japan and Korea

Japan boasts the world's highest level of octopus consumption, with Japanese consuming 60 percent of the world's catch at one point. Takoyaki (gooey dumplings made with octopus legs) is a snack associated with the Osaka area. The golf-ball-sized, gooey, balls are made on special pitted grittles in stands along the sidewalks. They are extremely hot with fish flakes and a sweet brown sauce. The octopus is chewy, the outside is soft and the inside is gooey

Reporting from Akashi near Kobe, Yasushi Wada wrote in the Yomiuri Shimbun, “To overcome the summer's enervating heat, Kansai folk have a recipe — serve up octopus. So popular is the belief in the Kansai region that consuming octopus is effective in relieving fatigue that July 2 unofficially has been named Day of the Octopus.” "Octopus can be caught throughout most of the year off Akashi, but it tastes best from July to the Bon season in August," said Yosuke Maeda, an employee of the Akashiura fisheries cooperatives. "In summer, shrimps and crabs, the favorite foods of octopuses, are abundant. So octopuses caught around this time are most delicious. "The current is strong in this area, which makes octopuses chewy and tastier." [Source: Yasushi Wada, Yomiuri Shimbun, July 2, 2010]

Takoyaki stall in Tokyo

Common octopus dishes in Korea include raw octopus, baby octopuses, stir-fried octopus, and seaweed and octopus. Nakji bokum is a popular, very spicy octopus dish. According to Trifood.com: Octopus tentacles are cut into bite-sized pieces then pan stir-fried with spicy gochujang (red chilli pepper paste) along with gochugaru (red chili pepper flakes), sesame oil, red/green chili peppers, green onions, carrots and onions. “

The ultimate in bizarre Korean eating experiences is downing live octopus (sannakji) with soju in an orange drinking tent. The octopus (a tender baby one called a nachi) is taken out of a tank and cut up into little pieces before your eyes and served on a plate. Not only is the octopus slimy and clammy it is still wiggling around and the suction cups on the tentacles still work. Sometimes you have to use a chopstick just to pry a piece off your plate. But once they are inside your mouth the pieces stick to your cheeks and crawl on your tongue, and sometimes emerge, sticking to your lips. The octopus is fresh out of a tank, quickly gutted and chopped into pieces. There is some danger. The suckers on the tentacles continue to function even when they are swallowed and people have choked to death after the suckers became attached to their throat.

Octopus Farms: Freezing One Million Octopuses to Death

Aquaculture firms have tried for years produce octopuses at a commercial scale in captivity, citing demand and pressure to find more sustainable alternatives to fishing. Critics argue the creatures are too smart — and capable of feeling pain — to be raised for food in confined quarters. Nueva Pescanova, a seafood company, operates a commercial octopus farm in Spain's Canary Islands, In 2019, the company boasted that it had succeeded at not only raising octopuses in captivity but also, for the first time, getting them to reproduce. [Source: Charles R. Davis, Business Insider, March 17, 2023]

In 2023, it was leaked that Nueva Pescanova was planning t slaughter roughly one million octopuses each year by submerging them alive in icy water. This caused a a big uproar, "It would be very cruel and should not be allowed," Dr. Peter Tse told the BBC. Business Insider reported: Campaigners with Eurogroup for Animals, an activist group, say that documents they obtained — and shared with the BBC — show that the proposed factory would subject octopuses to torturous conditions and a long, painful death.

In a report released in March 2023 the activist group said that Nueva Pescanova intends to slaughter around one million octopuses each year by submerging them in a freezing "ice slurry." In addition, it criticizes the conditions they will be kept in prior to their slaughter, saying the company intends to cage a solitary creature in dense housing — up to 15 octopuses per cubic meter of water — and subject them to 24-hour periods of light in an effort to speed reproduction.

Image Sources: Wikimedia Commons, NOAA

Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated April 2023

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