Biology:Giant Pacific octopus

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Short description: Species of cephalopod

Giant Pacific octopus
Temporal range: Pleistocene to recent[1]
Enteroctopus dolfeini.jpg
E. dofleini observed off Point Piños, California, at a depth of 65 m (213 ft)
Scientific classification edit
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Order: Octopoda
Family: Enteroctopodidae
Genus: Enteroctopus
Species:
E. dofleini
Binomial name
Enteroctopus dofleini
(Gerhard Wülker (fr), 1910)
Enteroctopus dofleini habitat range.jpg
Distribution of E. dofleini
Synonyms
  • Octopus punctatus Gabb, 1862
  • Octopus dofleini Wülker, 1910
  • Polypus dofleini Wülker, 1910
  • Octopus dofleini dofleini (Wülker, 1910)
  • Polypus apollyon Berry, 1912
  • Octopus dofleini apollyon (Berry, 1912)
  • Polypus gilbertianus Berry, 1912
  • Octopus gilbertianus Berry, 1912
  • Octopus apollyon (Berry, 1913)
  • Octopus madokai Berry, 1921
  • Paroctopus asper Akimushkin, 1963
  • Octopus dofleini martini Pickford, 1964

The giant Pacific octopus (Enteroctopus dofleini), also known as the North Pacific giant octopus, is a large marine cephalopod belonging to the genus Enteroctopus. Its spatial distribution includes the coastal North Pacific, along Mexico (Baja California), The United States (California, Oregon, Washington, and Alaska), Canada (British Columbia), Russia, Eastern China, Japan, and the Korean Peninsula.[3] It can be found from the intertidal zone down to 2,000 m (6,600 ft), and is best adapted to cold, oxygen-rich water. It is arguably the largest octopus species.

Etymology

The specific name dofleini was chosen by Gerhard Wülker in honor of German scientist Franz Theodor Doflein.[4] It was moved to genus Enteroctopus by Eric Hochberg in 1998.[5][6][7]

Description

Close-up of E. dofleini showing the longitudinal folds on the body and the paddle-like papillae
Close-up of suckers

Size

E. dofleini is distinguished from other species by its large size. Adults usually weigh around 15 kg (33 lb), with an arm span up to 4.3 m (14 ft).[8] The larger individuals have been measured at 50 kg (110 lb) and have a radial span of 6 m (20 ft).[3] American zoologist G. H. Parker found that the largest suckers on a giant Pacific octopus are about 6.4 cm (2.5 in) and can support 16 kg (35 lb) each.[3] The alternative contender for the largest species of octopus is the seven-arm octopus (Haliphron atlanticus) based on a 61-kilogram (134-pound) incomplete carcass estimated to have a live mass of 75 kg (165 lb).[9][10]

Ecology

Diet

E. dofleini preys on shrimp, crabs, scallops, abalones, cockles, snails, clams, lobsters, fish, squid, and other octopuses.[11][12][13] Food is procured with its suckers and then bitten using its tough beak of chitin. It has also been observed to catch spiny dogfish (Squalus acanthias) up to 1.2 m (4 ft) in length while in captivity.[14] 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.[15] 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.[16]

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 and filter feeders. Marine mammals, such as harbor seals, sea otters, and sperm whales depend upon the giant Pacific octopus as a source of food. Pacific sleeper sharks are also confirmed predators of this species.[17] In addition, the octopus (along with cuttlefish and squid) is a significant source of protein for human consumption. About 3.3 million tonnes (3.6 million short tons) are commercially fished, worth $6 billion annually.[3] Over thousands of years, humans have caught them using lures, spears, pot traps, nets, and bare hands.[18] The octopus is parasitized by the mesozoan Dicyemodeca anthinocephalum (nl), which lives in its renal appendages.[19]

Takoyaki stall in Nishi-Magome, Tokyo

Lifespan and reproduction

Enteroctopus dofleini spawning

Unlike most other octopus species, whose lifespans normally span only one year, the giant Pacific octopus has a lifespan of three to five years.[3] 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, and attached to a hard surface by the female. The 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 the female stays close to her spawn, never leaving to feed, leading to her death soon after the young have hatched.[20] The female's death is the result of starvation, as she subsists on her own body fats[21] during this period of approximately 6 months.[18] Hatchlings are about the size of a grain of rice,[22] and very few survive to adulthood. Their growth rate is quite rapid: starting from 0.03 g (0.0011 oz) and growing to 20–40 kg (44–88 lb) at adulthood, which is an increase of around 0.9% per day.[3] Because they are cool-blooded, they are able to use most of their consumed energy for body mass, respiration, physical activity, and reproduction.[18] During reproduction, the male octopus deposits a spermatophore (or sperm packet) more than 1 m (3.3 ft) long using his hectocotylus (specialized arm) in the female's mantle. Large spermatophores are characteristic of octopuses in this genus.[23] The female stores the spermatophore in her spermatheca 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.[18]

Hectocotylus arm of an octopod

Unlike males, only the female giant Pacific octopuses are semelparous, meaning they only breed a single time in their life.[21] After reproduction, they enter a stage called senescence, 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.[24]

Intelligence

Octopuses are ranked as the most intelligent invertebrates.[25] 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 with whom they frequently come in contact. These responses include jetting water, changing body texture, and other behaviors that are consistently demonstrated to specific individuals.[26] They have the ability to solve simple puzzles, open childproof bottles, and use tools.[18] The octopus brain has folded lobes (a distinct characteristic of complexity) and visual and tactile memory centers. They have about 300 million neurons.[18] They have been known to open tank valves, disassemble expensive equipment, and generally wreak havoc in labs and aquaria.[18] Some researchers even claim that they are capable of motor play[27] and having personalities.[28]

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 or evaluated in the IUCN Red List.[29] The giant Pacific octopus has not been assessed by the Monterey Bay Aquarium Seafood Watch, although other octopus species are listed.[30] 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.[18] 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).[citation needed]

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.[31] Populations in Puget Sound are not considered threatened.[citation needed]

Regardless of these data gaps in abundance estimates, future climate change scenarios 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.[citation needed]

Giant Pacific octopus

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)[32] Because their blue blood is copper-based (hemocyanin) and not an efficient oxygen carrier, octopuses favor and move toward cooler, oxygen-rich water. This dependency limits octopus habitat, typically to temperate waters 8–12 °C (46–54 °F).[3] If seawater temperatures continue to rise, these organisms may be forced to move to deeper, cooler water.

Each fall in Washington's Hood Canal, a habitat for many octopuses, phytoplankton and macroalgae 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.[33] 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.[18] 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.[citation needed]

Reproduction

Hatchlings

Increased seawater temperatures also increase metabolic processes. The warmer the water, the faster octopus eggs develop and hatch.[3] After hatching, the paralarvae swim to the surface to join other plankton, where they are often preyed upon by birds, fish, and other plankton feeders. Quicker hatching time may also affect critical timing for food availability.[34] One study found that higher water temperatures accelerated all aspects of reproduction and even shortened lifespan by up to 20%.[35] Other studies concur that warming climate scenarios should result in higher embryo and paralarvae mortalities.[36]

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.[37] As the ocean absorbs CO2, it becomes more acidic and lowers in pH. Ocean acidification lowers available carbonate ions, which is a building block for calcium carbonate (CaCO3). Calcifying organisms use calcium carbonate to produce shells, skeletons, and tests.[38] 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.[citation needed]

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.[18]

Toxins

Researchers have found high concentrations of heavy metals and PCBs in tissues and digestive glands, which may have come from these octopus' preferred prey, the red rock crab (Cancer productus).[39] These crabs bury themselves in contaminated sediments and eat prey that live nearby.[3] 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.[citation needed]

Effects on other trophic levels

Potential changes in octopus populations will affect upper and lower trophic levels.[34] 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.[citation needed]

See also

References

  1. ↑ "Distribution of Recent Cephalopoda and implications for Plio-Pleistocene events". https://www.researchgate.net/publication/228582620. 
  2. ↑ Allcock, L.; Taite, M.; Allen, G. (2018). "Enteroctopus dofleini". IUCN Red List of Threatened Species 2018: e.T162958A958049. doi:10.2305/IUCN.UK.2018-2.RLTS.T162958A958049.en. https://www.iucnredlist.org/species/162958/958049. Retrieved 30 October 2022. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Cosgrove, James (2009). Super Suckers, The Giant Pacific octopus. BC: Harbour Publishing. ISBN 978-1-55017-466-3. 
  4. ↑ Hansson, Hans G. (1997-11-14). "BEMON. D". https://www.bemon.loven.gu.se/petymol.d.html. 
  5. ↑ Hochberg, Frederick (Eric) George (1998). "Enteroctopus; Enteroctopus dofleini Wülker, 1910 new combination". Taxonomic Atlas of the Benthic Fauna of the Santa Maria Basin and the Western Santa Barbara Channel. 8. Santa Barbara, CA: Santa Barbara Museum of Natural History. pp. 203–208. ISBN 0-936494-13-1. 
  6. ↑ AZA Aquatic Invertebrate Taxon Advisory Group (AITAG) (September 2014). "Giant Pacific Octopus (Enteroctopus dofleini) Care Manual". Silver Spring, MD: Association of Zoos and Aquariums. p. 5. https://assets.speakcdn.com/assets/2332/giant_pacific_octopus_care_manual_final_9514.pdf. 
  7. ↑ Anderson, Roland C. (January 2001). "Name Change of the Giant Pacific Octopus". Drum And Croaker 32: 46. http://drumandcroaker.org/pdf/2001.pdf. 
  8. ↑ Smithsonian National Zoological Park: Giant Pacific Octopus .
  9. ↑ O'Shea, S. (2004). "The giant octopus Haliphron atlanticus (Mollusca : Octopoda) in New Zealand waters". New Zealand Journal of Zoology 31 (1): 7–13. doi:10.1080/03014223.2004.9518353. 
  10. ↑ O'Shea, S. (2002). "Haliphron atlanticus – a giant gelatinous octopus". Biodiversity Update 5: 1. http://isopods.nhm.org/pdfs/27566/27566.pdf. 
  11. ↑ Hartis, Colleen (2011-02-02). "ADW: Enteroctopus dofleini: INFORMATION". Animaldiversity.org. https://animaldiversity.org/accounts/Enteroctopus_dofleini/. 
  12. ↑ "Giant Pacific Octopus". https://oceana.org/marine-life/cephalopods-crustaceans-other-shellfish/giant-pacific-octopus. 
  13. ↑ "Giant Pacific octopus facts". 21 February 2018. http://www.animalspot.net/giant-pacific-octopus.html. 
  14. ↑ "Octopus Eats Shark". Google Video. http://video.google.com/videoplay?docid=-7004909622962894202. 
  15. ↑ Walla Walla University Marine Invertebrates Key: Giant Pacific Octopus
  16. ↑ Young, Gayne C. (8 May 2012). "PHOTOS: Pacific Octopus Eats Seagull, First Time Ever Photographed". Outdoor Life. https://www.outdoorlife.com/photos/gallery/fishing/2012/05/photos-pacific-octopus-easts-seagull-first-time-ever-documented/. 
  17. ↑ Sigler, M. F.; L. B. Hulbert; C. R. Lunsford; N. H. Thompson; K. Burek; G. O'Corry-Crowe; A. C. Hirons (24 July 2006). "Diet of Pacific sleeper shark, a potential Steller sea lion predator, in the north-east Pacific Ocean". Journal of Fish Biology 69 (2): 392–405. doi:10.1111/j.1095-8649.2006.01096.x. http://www.fau.edu/hboi/OceanHealth/PolarResearch/Publications/Sigler_et_al_2006_Pacific_sleeper_shark_diet.pdf. 
  18. ↑ 18.0 18.1 18.2 18.3 18.4 18.5 18.6 18.7 18.8 18.9 Courage, Katherine Harmon (2013). Octopus!. USA: The Penguin Group. ISBN 978-1-59184-527-0. 
  19. ↑ Furuya, Hidetaka; Tsuneki, Kazuhiko (2003). "Biology of Dicyemid Mesozoans". Zoological Science 20 (5): 519–532. doi:10.2108/zsj.20.519. PMID 12777824. 
  20. ↑ Scheel, David. "Giant Octopus: Fact Sheet". Alaska Pacific University. http://marine.alaskapacific.edu/octopus/factsheet.html. 
  21. ↑ 21.0 21.1 "Giant Pacific Octopus by Shawn Laidlaw". 3 November 2020. https://biologydictionary.net/giant-pacific-octopus/. 
  22. ↑ "Giant Pacific Octopus (Octopus dofleini)". NPCA. http://www.npca.org/marine_and_coastal/marine_wildlife/octopus.html. 
  23. ↑ Norman, M. 2000. Cephalopods: A World Guide. Hackenheim, ConchBooks, p. 214. ISBN:3-925919-32-5.
  24. ↑ Anderson, R. C.; Wood, J. B.; Byrne, R. A. (2002). "Octopus Senescence: The Beginning of the End". Journal of Applied Animal Welfare Science 5 (4): 275–283. doi:10.1207/S15327604JAWS0504_02. PMID 16221078. 
  25. ↑ Anderson, R. C. (2005). "How smart are octopuses?". Coral Magazine 2: 44–48. 
  26. ↑ Anderson, R. C.; Mather, J. A.; Monette, M. Q.; Zimsen, S. R. M. (2010). "Octopuses (Enteroctopus dofleini) Recognize Individual Humans". Journal of Applied Animal Welfare Science 13 (3): 261–272. doi:10.1080/10888705.2010.483892. PMID 20563906. https://animalstudiesrepository.org/cgi/viewcontent.cgi?article=1059&context=acwp_asie. 
  27. ↑ Tzar, Jennifer. "Through the Eye of an Octopus". https://www.discovermagazine.com/planet-earth/through-the-eye-of-an-octopus. 
  28. ↑ Mather, J. A.; Kuba, M. J. (2013). "The cephalopod specialties: complex nervous system, learning and cognition". Canadian Journal of Zoology 91 (6): 431–449. doi:10.1139/cjz-2013-0009. 
  29. ↑ "IUCN Red List of Threatened Species. Version 2013.2.". http://www.iucnredlist.org. 
  30. ↑ "Monterey Bay Seafood Watch". http://www.seafoodwatch.org/cr/SeafoodWatch/web/sfw_search.aspx?s=giant+pacific+octopus. 
  31. ↑ "Giant Pacific Octopus Rulemaking Process". http://wdfw.wa.gov/fishing/regulations/octopus/. 
  32. ↑ Mather, J. A.; Resler, S.; Cosgrove, J. A. (1985). "Activity and Movement patterns of Octopus dofleini". Journal of Marine Behavior and Physiology 11 (4): 301–14. doi:10.1080/10236248509387055. 
  33. ↑ Mather, J. A. (2010). Octopus: The Ocean's Intelligent Invertebrate.. Portland. London.: J.B. Timber Press. ISBN 978-1-60469-067-5. 
  34. ↑ 34.0 34.1 Andre, J; Haddon, M.; Pecl, G.T. (2010). "Modeling climate-change induced nonlinear thresholds in cephalopod population dynamics.". Global Change Biology 16 (10): 2866–2875. doi:10.1111/j.1365-2486.2010.02223.x. Bibcode: 2010GCBio..16.2866A. 
  35. ↑ Forsythe, J.W.; Hanlon, R.T. (1988). "Effect of temperature on laboratory growth, reproduction, and life span of Octopus bimaculoides". Marine Biology 98 (3): 369–379. doi:10.1007/bf00391113. http://oceanrep.geomar.de/34660/1/1518.pdf. 
  36. ↑ Repolho, Tiago (2014). "Developmental and physiological challenges of octopus (Octopus vulgaris) early life stages under ocean warming". Journal of Comparative Physiology B 184 (1): 55–64. doi:10.1007/s00360-013-0783-y. PMID 24100467. 
  37. ↑ Guinotte, J. M.; Fabry, V. J. (2008). "Ocean acidification and its potential effects on marine ecosystems.". Annals of the New York Academy of Sciences 1134 (1): 320–342. doi:10.1196/annals.1439.013. PMID 18566099. Bibcode: 2008NYASA1134..320G. 
  38. ↑ Gazeau, F.; Quiblier, C.; Jansen, J. M.; Gattuso, J. P.; Middelburg, J. J.; Heip, C. H. (2007). "Impact of elevated CO2 on shellfish calcification". Geophysical Research Letters 34 (7): L07603. doi:10.1029/2006gl028554. Bibcode: 2007GeoRL..34.7603G. http://www.agu.org/pubs/crossref/2007/2006GL028554.shtml. 
  39. ↑ Scheel, D.; Anderson, R. (2012). "Variability in the diet specialization of Enteroctopus dofleini (Cephalopoda: Octopodidae) in the eastern Pacific examined from midden contents.". American Malacological Bulletin 30 (2): 267–279. doi:10.4003/006.030.0206. 

External links

Wikidata ☰ Q912404 entry



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