UNUSUAL OCTOPUS SPECIES
There are around 300 species of Octopoda. Historically they were divided into two suborders, the Incirrina and the Cirrina. Incirrate octopuses (the majority of species) lack the cirri and paired swimming fins of the cirrates. In addition, the internal shell of incirrates is either present as a pair of stylets or absent altogether. Deep seas octopuses found at depths of around 1,000 meters (3,300 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. [Source: Wikipedia]
Jennifer A. Mather wrote in Natural History magazine, They "range in size from the one-ounce Atlantic pygmy octopus, Octopus joubini, to the giant Pacific octopus, Enteroctopus dofleini.. They are all ocean-dwellers, and, though the group is distributed from the poles to the tropics, octopuses are reclusive beasts; individuals are hard to find, let alone study.” [Source: Jennifer A. Mather, Natural History, February 2007]
"Ghost octopus" have pale, translucent skin. First identified by NOAA researchers near Hawaii in 2016, it is so new science doesn't have an official name for it yet. This octopus lives in deep sea areas. Females attach their eggs to a dead sponge and then wrap their body around it and remain that way for several years without feeding, to ensure that her young are protected. [Source: Mental Floss]
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
Venomous Octopuses and Mimic Octopuses
All octopuses produce venom, but only a few can cause death to humans. Three or four species of closely-related blue ringed octopus rank with some cone shells for the title of the world's most poisonous mollusks — and for that matter the most poisonous creature in the sea. Residing in the waters off of Australia, Indonesia, and parts of Southeast Asia, these species of octopus carry a toxin capable of killing a person in minutes, with some carrying enough toxin to kill 10 people. Fortunately the octopus are not aggressive, and bite only when taken out of the water and provoked.
Blue-ringed octopuses are the most well-known venomous octopuses. The name Blue-ringed Octopus is actually given to a group of octopods consisting of four different species: 1) the greater blue-ringed octopus (Hapalochlaena lunulata), 2) the southern blue-ringed octopus (Blue-ringed octopus), 3) the blue-lined octopus (Hapalochlaena fasciata) and 4) the common blue-ringed octopus (Hapalochlaena nierstraszi). These octopuses are small enough to fit in the palm of your hand. The greater blue-ringed octopus has larger rings than the blue-ringed octopus and is most commonly found on Australia's northern coast. Theblue-lined octopus, has lines instead of rings on its body and is found only in New South Wales. [Source: Ashleigh MacConnell, Animal Diversity Web (ADW); [ Harry Baker, Live Science, March 27, 2023]
The mimic octopus is a creature that mimics variety of sea creatures to escape creatures that hunt it. It was discovered in 1998 in the Lembah Strait off the coast of Sulawesi in Indonesia on the bottom of a muddy river mouth. For the nextt wo years, scientists filmed nine different mimic octopuses, impersonating sea snakes, lionfish, and flatfish — a strategy used to avoid predators. Mimic octopuses reach about 60 centimeters in length and are typically brown and white striped. [Source: marinebio.org]
Giant Pacific Octopus
The giant Pacific octopus (scientific name: Enteroctopus dofleini) is the largest octopus species. Also known as the North Pacific giant octopus, it belongs to the genus Enteroctopus and can reach a length of around five meters (16 feet) long and weigh over 250 kilograms (550 pounds). The length of the largest ones includes four-meter (13-foot) -long tentacles and a head the about the size of an American football. Typically though they weigh about 15 to 18 kilograms (33 to 40 pounds). Each of its eight arms are about 2.2 meters long (five feet) long and have 2000 suckers.
Giant Pacific octopuses have dorsal mantle that typically measures 50 to 60 centimeters (1.6 to 1.8 feet) in length. They are usually reddish in color but are able to change color and texture when threatened or for camouflage. The dorsal mantle is shaped like a sack and contains the brain, reproductive organs, digestive organs, and eyes. Giant Pacific octopuses have two eyes, one on each side of their head, which provide extremely acute vision. Giant Pacific octopuses also have four pairs of arms that extend from the mantle. Each pair is covered with up to 280 suckers, which contain thousands of chemical receptors.
Giant Pacific octopuses were commonly used as bait for Pacific halibut during the late 1950s and 1960s, but this is no longer the case. They are as commonly eaten and commercially fished as some other octopus species in Asia. Although their numbers are not they are not considered at risk by the International Union for Conservation of Nature (IUCN) Red List, the International Trade in Endangered Species (CITES) or the US Federal List of Endangered Species.
Smallest Octopus Species
The star-sucker pygmy octopus (Octopus wolfi) is regarded as the world’s smallest octopus. Found in shallow waters throughout the Pacific and Indian Oceans, it is about the size of bottle cap — with a length of 2.5 centimeters (one inch) — and weighs about the same as a raisin — about 1 gram (0.04 ounces). Their short lifespan is only around 6 months. The Star-Sucker Pygmy Octopus spends much of its time floating near the surface feeding on plankton. Once they become big enough to survive on the reef, they hunt small crustaceans and shellfish. Unlike most species of octopus, which only lay eggs once and then die, this little felloe can lay multiple clutches of eggs. Female Star-Sucker Pygmy Octopuses will lay one batch of eggs, look after them till they hatch, and immediately lay another batch right after. They have been observed doing this up to three times. [Source: Octonation]
The hairy octopus is about the the size of a large paper clip and looks like a tiny ball of algae. Not discovered until the early 2000s, it has a total head length of up to five centimeters (two inches), with arms ranging from three to ten centimeters (one to four inches) in length. Due to their size and their ability to blend into the environments where they live they are incredibly hard to spot. They live in areas with fine rubble, sea grass, volcanic black sand with algae patches at depths between eight and 20 meters (26-65 feet). Their “hairiness “ comes from fuzzy papillae on their skin which can create fuzzy bumps and ridges. These octopuses have been spotted in waters off Bali and the Lembeh Strait in Indonesia and Okinawa in Japan.
The male violet blanket Octopus (Termoctopus violaceus) is very small but females can grow up to two meters (6.6 feet). For more on them see below. Males are much less impressive looking than females and only grow to 2.3 centimeters (0.9 inches ) — about the size of a walnut, making them literally small enough to fit into fit inside the pupil of the female! Male Argonauta argo are also very small. See Below.
Common octopuses (Scientific name: Octopus vulgaris) have a world-wide distribution and are native to the Indian Ocean, Atlantic Ocean and Pacific Ocean. They are particularly abundant in the Mediterranean Sea, the Eastern Atlantic Ocean, and in Japanese waters. Common octopuses are found in tropical, subtropical, and temperate waters between the surface and a depth of 100 to 150 meters (330 to 500 feet). It lives in reefs, coastal areas, on or near the sea bottom and on the upper part of the continental shelf. These octopus have a life span of 12 to 24 months. They are semelparous, which means that offspring are all produced in a single group, after which the parents usually dies.[Source: Robin J. Case, Animal Diversity Web (ADW) /=]
Common octopuses reach 30 centimeters to one meter (1-3 feet) in length including arms. The skin is smooth. Like other octopuses, members of this species have eight arms that are lined with suckers, and they lack any internal shell. They are cold blooded (ectothermic, use heat from the environment and adapt their behavior to regulate body temperature).
Common octopus are active predators that feed primarily on gastropods and bivalves. Small hatchlings typically spend several weeks as active predators in the plankton before they settle down to the benthic (living on or near the bottom of the sea) mode of life at a size of about 0.2 grams. /=\
Common octopus are widely eaten people in Japan, Korea and the Mediterranean. In 1975, some 121,000 tons of Common octopus were caught by fisheries. In 1976, the number was 137,000 tons. There are some concerns about overfishing but they have not been evaluated for the International Union for Conservation of Nature (IUCN) Red List.
Common Octopus Behavior
Common octopus are a typically nocturnal (active at night), not only in the wild but also in the laboratory. They keep there homes — usually a crevice or sheltered place — hidden with shells, stones, and other solid objects they gather. According to Animal Diversity Web: Members of this species are perfectly adapted to live in very different habitats. Their capacity to conceal themselves on any substrate by varying colour, skin, texture, and posture is challenged by few other cephalopod species. [Source: Robin J. Case, Animal Diversity Web (ADW) /=]
Common octopuses are normally solitary and territorial (defend an area within the home range). They make their homes near to other octopuses of similar size. If animals share a tank, each will try to occupy a home or settle down at some distance from the other inhabitants. This individualistic behavior is only interrupted during mating and spawning, but even then females brood their eggs in isolation. When not traveling in- or offshore,
Common octopus seems to be a truly sedentary, species. Underwater observations showed that the animals remain in their dens; they leave them at dusk for hunting trips and return at dawn. Excursions during the day in search of food are of shorter duration. Some octopuses may occupy the same home for a longer period while others change holes several times over a few days. /=\
In the Catalonian Sea, more particularly in the area of Banyuls and Port Vendres, Common octopus seems to undergo seasonal migrations, mainly of vertical orientation. In the early spring, large animals move inshore for spawning. The females tend to disappear during the summer; they lay eggs, brood, and die. From late summer onwards, the largest size class consists mainly of males. They leave the coastal waters in autumn or early summer; at this time the males are mature, and the females at different stages of maturation. Some of these females probably spawn in autumn, others might leave the coastal waters over the winter season and spawn in early spring, joining the animals of the first group. A third group, consisting of immature animals, invades the shallow waters in late spring. While males mature during the summer, females are likely to depart to deeper waters and return to coastal areas in spring for spawning. Doubtless, there is a vertical migratory (make seasonal movements between regions, such as between breeding and wintering grounds), movement in relation to spawning. Generally, the abundance of this species decreases with depth and is nearly zero at the continental shelf. /=\
Common octopus are oviparous (young are hatched from eggs) and engage in internal reproduction in which sperm from the male parent fertilizes an egg from the female parent. They engage in seasonal breeding and year-round breeding. The number of offspring ranges from 100,000 to 500,000. The duration of embryonic development is related to temperature, as it is in all cephalopods, and it also depends on the size of the egg. /=\
Gloomy octopuses (Octopus tentricus) are native to the waters off the coasts of Australia and New Zealand and most commonly seen on intertidal rocky shores and in the ocean off New South Wales, Australia. Also known as common Sydney) octopuses, they are grey with rusty brown arm tips and white eyes. They mostly eats mollusks but females have been documented eating males of their own own species, according to the Australian Museum. [Source: Isaac Schultz, Gizmodo, November 10, 2022]
Gloomy octopuses reach 80 centimeters (2.6 feet) in length. At night they hunt and use their sharp beak to break open snail, crab and bivalve shells and extract the meat inside. They can change their colour of its skin and shape to imitate seaweed. These octopus are territorial and spends most of the day hiding away, surrounded by rocks and rubble that they have collected to defend their home.
Gloomy octopuses belongs to the common octopus (Octopus vulgar) species group and have many similarities with other members of the group. Gloomy octopuses have been the subject of studies on octopuses in the wild as they demonstrate some rarely observed social activities.
Dumbo Octopuses — Deep Sea Octopuses
Dumbo octopus is the common name for Grimpoteuthis, a genus of pelagic finned or cirrate octopods. The name "dumbo" originates from their resemblance to the main character in 1941 Disney's film “Dumbo”. These octopus have prominent ear-like fins which extends from the mantle above each eye. There are 17 species recognized in the genus. Prey include crustaceans, bivalves, worms and copepods. Their average life span is three to five years. [Source: Wikipedia]
Dumbo octopus species are are assumed to have a worldwide distribution, even though they have been rarely observed because they make their homes in cold, abyssal depths ranging from 1,000 to 7,000 meters (1 to 7, kilometers). Specimens have been found off the coasts of Oregon, the Philippines, Martha's Vineyard, the Azores, New Zealand, Australia, California, the Gulf of Mexico, Papua and New Guinea.
Dumbo octopuses are the deepest living octopuses known, and among the deepest living creatures period.. One specimen was captured 60 kilometers southeast of Grand Cayman in the Cayman Trench at a depth of 7,279 meters (23,881 feet), but the depth is not verified because the specimen may have been captured while the net was descending to depth.
World's Deepest Octopus Spotted at 6,957 Meters (22,825 Feet) Down
In May 2020 the deepest ever sighting of an octopus was made by cameras on the Indian Ocean floor at a depth of almost seven kilometers (4.3 miles) in the Java Trench — almost two kilometers deeper than the previous reliable recording. The BBC reported: Researchers, who report the discovery in the journal Marine Biology, say it's a species of "Dumbo" octopus. The name is a nod to the prominent ear-like fins just above these animals' eyes that make them look like the 1940s Disney cartoon character. [Source: Jonathan Amos, BBC, May 29, 2020]
The scientist behind the identification is Dr Alan Jamieson. He's pioneered the exploration of the deep using what are called "landers". These are instrumented frames dropped overboard from research ships. They settle on the seabed and record what passes by. Dr Jamieson has discovered a host of deep-sea organisms using lander technology
Dr Jamieson's equipment filmed two octopuses — one on a drop to 5,760 meters (18,897 feet) and a second to 6,957 meters (22,825 feet). The individual animals were 43 centimeters (1.4 feet) and 35 centimeters (1.1 feet) in length. They've been placed in the Grimpoteuthis family — the group commonly known as Dumbo. Octopus fragments and eggs have been found at very great depths, but until this discovery, the previous deepest reliable sighting was at 5,145m down. That was a black and white photo of an animal taken 50 years ago off Barbados.
The significance of the Indian Ocean observations is that we now know that octopuses can find potentially suitable habitat across at least 99 percent of the global seafloor. But those animals that do live at depth will clearly need some special adaptations, says Dr Jamieson. "They'd have to do something clever inside their cells. If you imagine a cell is like a balloon - it's going to want to collapse under pressure. So, it will need some smart biochemistry to make sure it retains that sphere," the scientist explained. "All the adaptations you need to live at pressure are at the cellular level."
Rare Blanket Octopus Spotted off Australia
Female blanket octopuses are red in color and have transparent webs connecting some of their arms. When they swim the webbing flows like a long scarf blown in the wind. The "blanket" is used to scare off potential predators. When the octopus feels threatened it spreads its arms and looks like a vampire opening its cape, making it appear bigger than it actually is. Male blanket octopuses are much smaller than females (See Smallest Octopuses above) but they have one cool trick. They can strip the stinging tentacles from jellyfish to use them to protect themselves.
In January 2022, Jordan Mendoza wrote in USA TODAY: “A marine biologist had a "once in a lifetime" encounter with the rare and stunning blanket octopus off the coast of Australia. “Jacinta Shackleton, a videographer and photographer, has been capturing wildlife in Great Barrier Reef for the past three years as a content creator for Queensland's Tourism and Events. On January 6, Shackleton posted on Instagram that she had spotted the elusive octopus while snorkeling near Lady Elliot Island. “"When I first saw it, I thought it could have been a juvenile fish with long fins, but as it came closer, I realized it was a female blanket octopus and I had this overwhelming sense of joy and excitement," Shackleton told The Guardian. "I kept yelling through my snorkel, 'It’s a blanket octopus!' I was so excited I was finding it difficult to hold my breath to dive down and video it." [Source: Jordan Mendoza, USA TODAY, January 18, 2022]
“Found living around coral reefs in subtropical and tropical oceans, the blanket octopus gets its name from its cape-like webs enclosing its tentacles, often used to intimidate predators. They are immune to jellyfish stings and will use ripped-off jellyfish tentacles to hunt for prey like small fishes. "The blankets can be folded under the octopus’ arms to make for a faster getaway, if needed. This cape can be detached when the octopus is in distress, to distract or cling to a predator," says the Great Barrier Reef Foundation. The foundation said it's deadly for the species to mate because the male "expends all its resources" while breaking off a third arm and dying soon after. Females will carry more than 100,000 eggs until they hatch. The female then usually dies.
“The creature Shackleton saw is female, and the species has the "largest gender size discrepancy in the animal kingdom," according to the foundation. Females grow to more than 6 feet long, while males measure 2.4 centimeters, about the size as a thumbtack. Females weigh 40,000 times more than males. A male blanket octopus hadn't been observed until 2002, according to the New Zealand Journal of Marine and Freshwater Research. Shackleton told The Guardian she believes the creature has been spotted only three times before in the area.
Argonauta Argo and Its Unusual Mating
Argonauta argo, also known as the paper nautilus, argonaut octopus and greater argonaut, is a species of pelagic octopus belonging to the genus Argonauta. It is also known as the paper nautilus after the shell it builds to hold its eggs, which is made of paper-thin calcium carbonate). Its Chinese name translates to "white sea-horse's nest". A. argo was the first argonaut species to be described and is consequently gave its name to the genus. Though rarely seen by humans, it is widespread in tropical oceans waters and is preyed upon by tuna, dolphins, and billfishes and is described as of least concern on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. [Source: Wikipedia]
In ancient Greek mythology, the Argonauts helped Jason seek the Golden Fleece. In 300 B.C. Aristotle described his vision of a female argonaut using her shell as a boat and her tentacles as sails and oars. In 2010 octopus experts Julian Finn and Mark Norman documented what actually occurs: The argonaut moves by expelling jets of water, surfaces enough to trap air in her shell, then is buoyed at an optimal water level by the air bubble.
Females drift along the open seas in their homemade translucent shell. They can grow to over 38 centimeters (15 inches) whereas the male rarely reaches 2.5 centimeters (one inch). Males are semelparous — they only mate once and then die — but females are iteroparous and can lay eggs multiple times throughout their lifetime. Argonauta argo’s reproduction is unusual to say the least. The tiny male lodges a detachable, sperm-bearing tentacle in a female up to 30 times his size. National Geographic reported: “This octopus species lives in open water — not the easiest place to find a mate, especially since the male is tiny — less than three-quarters of an inch long — while the female can be up to 30 times his size. She has two specialized dorsal arms that secrete a chalky substance, forming a pleated shell in which she can hide, float, and brood eggs. The male is sans shell, but he too has a specialized arm: a tentacle-like, detachable copulatory organ called a hectocotylus. [Source: Patricia Edmonds Andeva Van Den Berg, National Geographic, July 2019]
After attaching to the female, the male releases his hectocotylus, which worms its way into the female’s mantle cavity. She may stockpile these disembodied sperm arms from several mates and use them to fertilize her eggs over time. She’ll lay strings of eggs tethered to her shell (also called an egg case) where she can tend them as they develop. Scientists know this because they’ve been able to observe argonaut mothers live — but not fathers. After donating his paternal part, no male has been seen alive growing a new one; only dead specimens have been found. As his last act, the small but mighty paterfamilias gives an arm and a life to the cause of 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