Giant Pacific Octopus
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The giant Pacific octopus (''Enteroctopus dofleini''), also known as the North Pacific giant octopus, is a large marine
cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...
belonging to the
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
'' Enteroctopus''. Its spatial distribution includes the coastal
North Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
, along Mexico (Baja California), The United States (California, Oregon, Washington, and Alaska), Canada (British Columbia), Russia, Eastern China, Japan, and the Korean Peninsula. It can be found from the
intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...
down to , and is best adapted to cold, oxygen-rich water. It is the largest
octopus An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttle ...
species, based on a scientific record of a individual weighed live.


Etymology

The specific name ''dofleini'' was chosen by Gerhard Wülker in honor of German scientist
Franz Theodor Doflein Franz Theodor Doflein (5 April 1873, in Paris – 24 August 1924, in Obernigk, near today's Wrocław) was a German zoologist known for his studies of animal ecology. Biography He studied medicine and zoology at the University of Munich, where h ...
. It was moved to genus '' Enteroctopus'' by Eric Hochberg in 1998.


Description


Size

''E. dofleini'' is distinguished from other species by its large size. Adults usually weigh around , with an arm span up to .Smithsonian National Zoological Park: Giant Pacific Octopus
.
The larger individuals have been measured at and have a radial span of . American zoologist G. H. Parker found that the largest suckers on a giant Pacific octopus are about and can support each. The alternative contender for the largest species of octopus is the
seven-arm octopus The seven-arm octopus (''Haliphron atlanticus'') is one of the two largest known species of octopus; based on scientific records, it has a maximum estimated total length of and mass of . The only other similarly large extant species is the gia ...
(''Haliphron atlanticus'') based on a incomplete carcass estimated to have a live mass of . However, a number of questionable size records would suggest ''E. dofleini'' is the largest of all octopus species by a considerable margin,Norman, M. 2000. ''Cephalopods: A World Guide''. Hackenheim, ConchBooks, p. 214. . including a report of one up to in weight with a arm span. ''
Guinness World Records ''Guinness World Records'', known from its inception in 1955 until 1999 as ''The Guinness Book of Records'' and in previous United States editions as ''The Guinness Book of World Records'', is a reference book published annually, listing world ...
'' lists the biggest as with an arm span of . A UN catalog of octopuses sizes ''E. dofleini'' at with an arm length of .


Ecology


Diet

''E. dofleini'' preys upon shrimp, crabs, scallop, abalone, cockles, snails, clams, lobsters, fish, squid, and other octopuses. Food is procured with its suckers and then bitten using its tough beak of
chitin Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...
. It has also been observed to catch
spiny dogfish The spiny dogfish (''Squalus acanthias''), spurdog, mud shark, or piked dogfish is one of the best known species of the Squalidae (dogfish) family (biology), family of sharks, which is part of the Squaliformes order. While these common names ma ...
(''Squalus acanthias'') up to in length while in captivity. Additionally, consumed carcasses of this same shark species have been found in giant Pacific octopus middens in the wild, providing strong evidence of these octopuses preying on small sharks in their natural habitat.Walla Walla University Marine Invertebrates Key: Giant Pacific Octopus
In May 2012, amateur photographer Ginger Morneau was widely reported to have photographed a wild giant Pacific octopus attacking and drowning a seagull, demonstrating that this species is not above eating any available source of food within its size range, even birds.


Predators

Scavengers and other organisms often attempt to eat octopus eggs, even when the female is present to protect them. Giant Pacific octopus paralarvae are preyed upon by many other
zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...
and
filter feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...
s. Marine mammals, such as
harbor seal The harbor (or harbour) seal (''Phoca vitulina''), also known as the common seal, is a true seal found along temperate and Arctic marine coastlines of the Northern Hemisphere. The most widely distributed species of pinniped (walruses, eared sea ...
s,
sea otter The sea otter (''Enhydra lutris'') is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between , making them the heaviest members of the weasel family, but among the small ...
s, and
sperm whale The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus ''Physeter'' and one of three extant species in the sperm whale famil ...
s depend upon the giant Pacific octopus as a source of food.
Pacific sleeper shark The Pacific sleeper shark (''Somniosus pacificus'') is a sleeper shark of the family Somniosidae, found in the North Pacific on continental shelves and slopes in Arctic and temperate waters between latitudes 70°N and 22°N, from the surface t ...
s are also confirmed predators of this species. In addition, the octopus (along with cuttlefish and squid) is a significant source of protein for human consumption. About are commercially fished, worth $6 billion annually. Over thousands of years, humans have caught them using lures, spears, pot traps, nets, and bare hands. The octopus is parasitized by the
mesozoa The Mesozoa are minuscule, worm-like parasites of marine invertebrates. Generally, these tiny, elusive creatures consist of a somatoderm (outer layer) of ciliated cells surrounding one or more reproductive cells. A recent study recovered Mesoz ...
n , which lives in its renal appendages.


Lifespan and reproduction

The giant Pacific octopus is considered to be long-lived compared to other species, with lifespans typically 3–5 years in the wild. Many other octopuses go through a complete life cycle in one year, from egg to end of life. To help compensate for its relatively short lifespan, the octopus is extremely prolific. It can lay between 120,000 and 400,000 eggs which are coated in
chorion The chorion is the outermost fetal membrane around the embryo in mammals, birds and reptiles (amniotes). It develops from an outer fold on the surface of the yolk sac, which lies outside the zona pellucida (in mammals), known as the vitelline ...
, and attached to a hard surface by the female. The
spawn Spawn or spawning may refer to: * Spawn (biology), the eggs and sperm of aquatic animals Arts, entertainment, and media * Spawn (character), a fictional character in the comic series of the same name and in the associated franchise ** '' Spawn: ...
is intensively cared for exclusively by the female, who continuously blows water over it and grooms it to remove algae and other growths. While she fulfills her duty of
parental care Parental care is a behavioural and evolutionary strategy adopted by some animals, involving a parental investment being made to the evolutionary fitness of offspring. Patterns of parental care are widespread and highly diverse across the animal k ...
the female stays close to her spawn, never leaving to feed, leading to her death soon after the young have hatched. The female's death is the result of starvation, as she subsists on her own body fats during this period of approximately 6 months. Hatchlings are about the size of a grain of rice, and very few survive to adulthood. Their growth rate is quite rapid: starting from and growing to at adulthood, which is an increase of around 0.9% per day. Because they are cool-blooded, they are able to use most of their consumed energy for body mass, respiration, physical activity, and reproduction. During reproduction, the male octopus deposits a
spermatophore A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores ...
(or sperm packet) more than long using his
hectocotylus A hectocotylus (plural: ''hectocotyli'') is one of the arms of male cephalopods that is specialized to store and transfer spermatophores to the female. Structurally, hectocotyli are muscular hydrostats. Depending on the species, the male may use i ...
(specialized arm) in the female's mantle. Large spermatophores are characteristic of octopuses in this genus. The female stores the spermatophore in her
spermatheca The spermatheca (pronounced plural: spermathecae ), also called receptaculum seminis (plural: receptacula seminis), is an organ of the female reproductive tract in insects, e.g. ants, bees, some molluscs, oligochaeta worms and certain other ...
until she is ready to fertilize her eggs. One female at the Seattle Aquarium was observed to retain a spermatophore for seven months before laying fertilized eggs. Unlike males, only the female giant Pacific octopuses are
semelparous Semelparity and iteroparity are two contrasting reproductive strategies available to living organisms. A species is considered semelparous if it is characterized by a single reproductive episode before death, and iteroparous if it is characteri ...
, meaning they only breed a single time in their life. After reproduction, they enter a stage called
senescence Senescence () or biological aging is the gradual deterioration of functional characteristics in living organisms. The word ''senescence'' can refer to either cellular senescence or to senescence of the whole organism. Organismal senescence inv ...
, which involves obvious changes in behavior and appearance, including a reduced appetite, retraction of skin around the eyes giving them a more pronounced appearance, increased activity in uncoordinated patterns, and white lesions all over the body. While the duration of this stage is variable, it typically lasts about one to two months. Death is typically attributed to starvation, as the females have stopped hunting in order to protect their eggs; males often spend more time in the open, making them more likely to be preyed upon.


Intelligence

Octopuses are ranked as the most intelligent invertebrates. Giant Pacific octopuses are commonly kept on display at aquariums due to their size and interesting physiology, and have demonstrated the ability to recognize humans whom they frequently come in contact with. These responses include jetting water, changing body texture, and other behaviors that are consistently demonstrated to specific individuals. They have the ability to solve simple puzzles, open childproof bottles and use tools. The octopus brain has folded lobes (a distinct characteristic of complexity), visual and tactile memory centers. They have about 300 million
neurons A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. N ...
. They have been known to open tank valves, disassemble expensive equipment, and generally wreak havoc in labs and aquaria. Some researchers even claim that they are capable of motor play and having personalities.


Conservation and climate change

Giant Pacific octopuses are not currently under the protection of
Convention on International Trade in Endangered Species of Wild Fauna and Flora CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of intern ...
or evaluated in the
IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
. The giant Pacific octopus has not been assessed by the Monterey Bay Aquarium
Seafood Watch __NOTOC__ Seafood Watch is a sustainable seafood advisory list, and has influenced similar programs around the world. It is best known for developing science-based seafood recommendations that consumers, chefs, and business professionals use to i ...
, although other octopus species are listed. Combined with lack of assessment and mislabeling, tracking the species's abundance is nearly impossible. Scientists have relied on catch numbers to estimate stock abundance, but the animals are solitary and difficult to find. DNA techniques have assisted in genetic and phylogenetic analysis of the species' evolutionary past. Following its DNA analysis, the giant Pacific octopus may actually prove to be three subspecies (one in Japan, another in Alaska, and a third in
Puget Sound Puget Sound ( ) is a sound of the Pacific Northwest, an inlet of the Pacific Ocean, and part of the Salish Sea. It is located along the northwestern coast of the U.S. state of Washington. It is a complex estuarine system of interconnected ma ...
). In Puget Sound, the Washington Fish and Wildlife Commission adopted rules for protecting the harvest of giant Pacific octopuses at seven sites, after a legal harvest caused a public outcry. Populations in Puget Sound are not considered threatened. Regardless of these data gaps in abundance estimates, future
climate change scenarios Climate change scenarios or socioeconomic scenarios are projections of future greenhouse gas (GHG) emissions used by analysts to assess future vulnerability to climate change. Scenarios and pathways are created by scientists to survey any long ...
may affect these organisms in different ways. Climate change is complex, with predicted biotic and abiotic changes to multiple processes including oxygen limitation, reproduction, ocean acidification, toxins, effects on other trophic levels, and
RNA editing RNA editing (also RNA modification) is a molecular process through which some cells can make discrete changes to specific nucleotide sequences within an RNA molecule after it has been generated by RNA polymerase. It occurs in all living organisms ...
.


Oxygen limitation

Octopuses have been found to migrate for a variety of reasons. Using tag and recapture methods, scientists found they move from den to den in response to decreased food availability, change in water quality, increase in predation, or increased population density (or decreased available habitat/den space) Because their blue blood is copper-based (
hemocyanin Hemocyanins (also spelled haemocyanins and abbreviated Hc) are proteins that transport oxygen throughout the bodies of some invertebrate animals. These metalloproteins contain two copper atoms that reversibly bind a single oxygen molecule (O2) ...
) and not an efficient oxygen carrier, octopuses favor and move toward cooler, oxygen-rich water. This dependency limits octopus habitat, typically to temperate waters . If seawater temperatures continue to rise, these organisms may be forced to move to deeper, cooler water. Each fall in Washington's
Hood Canal Hood Canal is a fjord forming the western lobe, and one of the four main basins,phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'. Ph ...
and
macroalgae Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), ''Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as k ...
die and create a dead zone. As these micro-organisms decompose, oxygen is used up in the process and has been measured to be as low as 2 parts per million (ppm). This is a state of hypoxia. Normal levels are measured at 7–9 ppm. Fish and octopuses move from the deep towards the shallow water for more oxygen. Females do not leave, and die with their eggs at nesting sites. Warming seawater temperatures promote phytoplankton growth, and annual dead zones have been found to be increasing in size. To avoid these dead zones, octopuses must move to shallower waters, which may be warmer in temperature and less oxygen-rich, trapping them between two low-oxygen zones.


Reproduction

Increased seawater temperatures also increase metabolic processes. The warmer the water, the faster octopus eggs develop and hatch. After hatching, the
paralarvae Paralarvae (singular: ''paralarva'') are young cephalopods in the planktonic stages between hatchling and subadult. This stage differs from the larval stage of animals that undergo true metamorphosis. Paralarvae have been observed only in mem ...
swim to the surface to join other
plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...
, where they are often preyed upon by birds, fish, and other plankton feeders. Quicker hatching time may also affect critical timing for food availability. One study found that higher water temperatures accelerated all aspects of reproduction and even shortened lifespan by up to 20%. Other studies concur that warming climate scenarios should result in higher embryo and paralarvae mortalities.


Ocean acidification

The burning of fossil fuels, deforestation, industrialization, and other land-use changes cause increased carbon dioxide levels in the atmosphere. The ocean absorbs an estimated 30% of emitted anthropogenic CO2. As the ocean absorbs CO2, it becomes more acidic and lowers in pH.
Ocean acidification Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...
lowers available carbonate ions, which is a building block for calcium carbonate (CaCO3). Calcifying organisms use calcium carbonate to produce shells, skeletons, and tests. The prey base that octopuses prefer (crab, clams, scallops, mussels, etc.) are negatively impacted by ocean acidification, and may decrease in abundance. Shifts in available prey may force a change in octopus diets to other, nonshelled organisms. Because octopuses have hemocyanin as copper-based blood, a small change in pH can reduce oxygen-carrying capacity. A pH change from 8.0 to 7.7 or 7.5 will have life-or-death effects on cephalopods.


Toxins

Researchers have found high concentrations of heavy metals and
PCBs Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act in 1979 and internationally by t ...
in tissues and digestive glands, which may have come from these octopus' preferred prey, the red rock crab (''Cancer productus''). These crabs bury themselves in contaminated sediments and eat prey that live nearby. What effects these toxins have on octopuses are unknown, but other exposed animals have been known to show liver damage, changes in immune systems, and death.


Effects on other trophic levels

Potential changes in octopus populations will affect upper and lower
trophic level The trophic level of an organism is the position it occupies in a food web. A food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the number of steps it i ...
s. Lower trophic levels include all prey items, and may fluctuate inversely with octopus abundance. Higher trophic levels include all predators of octopuses, and may fluctuate with octopus abundance, although many may prey upon a variety of organisms. Protection of other threatened species may affect octopus populations (the sea otter, for example), as they may rely on octopuses for food. Some research suggests that fishing other species has aided octopus populations, by taking out predators and competitors.


RNA editing

Some octopuses exhibit the ability to alter speeds of sodium and potassium ion movement across cell membranes, allowing them to live in very cold water. Researchers at the
University of Puerto Rico The University of Puerto Rico ( es, Universidad de Puerto Rico, UPR) is the main public university system in the U.S. Commonwealth of Puerto Rico. It is a government-owned corporation with 11 campuses and approximately 58,000 students and 5,3 ...
's Institute of Neurobiology have found that they have altered protein synthesis, and can speed up production of potassium channels in cold water to keep up with sodium ion exchange. They are now looking into whether individuals can alter their protein synthesis in response to changing temperatures, or if this change occurs species-wide, over long-term adaptations. If changes are possible by the individual, these octopuses might be able to adapt quickly to changing climate scenarios.


See also

*
Octopus wrestling Octopus wrestling involves a diver grappling with a large octopus in shallow water and dragging it to the surface.Norman, M.D. (2000). Octopus Wrestling. In: ''Cephalopods: A World Guide''. ConchBooks, pp. 217-218. Although it was called "wres ...
*
Cephalopod size Cephalopods vary enormously in size. The smallest are only about long and weigh less than at maturity, while the largest—the giant and colossal squids—can exceed in length and weigh close to half a tonne (), making them the largest living ...
*
Squidward Tentacles Squidward Q. Tentacles is a fictional character voiced by actor Rodger Bumpass in the Nickelodeon animated television series ''SpongeBob SquarePants''. Squidward was created and designed by marine biologist and animator Stephen Hillenburg. He f ...
, a fictional Giant Pacific octopus.


References


External links


The Cephalopod Page
{{Taxonbar, from=Q912404 Octopodidae Molluscs of the Pacific Ocean Marine molluscs of Asia Cephalopods of North America Molluscs of Japan Fauna of California Western North American coastal fauna Molluscs described in 1910