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Octopus

Eight-limbed, intelligent mollusc of the order Octopoda.

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Octopus

albert kok · via Wikipedia: Octopus · CC BY-SA 3.0

The scientific Latin term comes from Ancient Greek words for 'eight' and 'foot'.[1] Creatures belonging to the order Octopoda are molluscs with eight limbs and a soft body.[2] Three hearts and a closed circulatory system are features of octopuses.[3]

Quick Facts

Scientific classification
Order Octopoda, class Cephalopoda
Largest species
Giant Pacific octopus (Enteroctopus dofleini), up to 71 kg (157 lb) live mass
Smallest species
Octopus wolfi, around 2.5 cm (0.984 in) and less than 1 g
Lifespan
Short-lived; most species grow quickly and mature early
Venom
All octopuses are venomous; only blue-ringed octopuses are deadly to humans

Facts from the source article.

Key facts and history

The standard English plural is octopuses, while octopi is considered etymologically incorrect.[4] The giant Pacific octopus is often cited as the largest species, with adults usually weighing 10 to 50 kg.[5] Each sucker is circular and bowl-like, with an outer infundibulum and an inner acetabulum.[6] Weighing under 1 g and measuring roughly 2.5 cm, Octopus wolfi is the tiniest species.[5]

A sharp beak made of chitin is found in the mouth, which, along with the brain, is located in the head.[7] Color change is made possible by a thin outer epidermis and a fibrous dermis that together form the skin.[8] Octopuses possess three hearts as part of a closed circulatory system.[3] A bluish tint to the blood results from the presence of copper-rich haemocyanin.[9]

Water is taken in through an aperture, passes over the gills, and is then expelled via the siphon during respiration.[10] Lifespans for octopuses are short, with a maximum of four years; for some species, the entire life cycle is completed in under six months.[11]

What the cited sources add

The MarineBio account notes that Grimpoteuthis octopuses are nicknamed "dumbo octopuses" due to ear-like fins.[12] These fins are supported by an internal shell, differing from other octopuses.[12] Four modes of active locomotion have been observed in dumbo octopuses: crawling, take-off, fin swimming, and pumping.[12] The ovaries of these octopuses contain eggs at different stages, implying continual breeding.[12]

Norman's ABC Science article states that all 1000 or so cephalopod species are voracious carnivores.[13] A pale octopus species was found living at 2400 metres depth around hydrothermal vents near Antarctica.[13]

References

  1. Wikipedia, "Octopus" (CC BY-SA 4.0), which cites: ; "Octopus", Dictionary.reference.com; , . (original not read by us) en.wikipedia.org
  2. Wikipedia, "Octopus" (CC BY-SA 4.0) en.wikipedia.org
  3. Wikipedia, "Octopus" (CC BY-SA 4.0), which cites: Wells, "Octopus, Physiology and Behaviour of an Advanced Invertebrate", Springer Science+Business Media, 1978; Courage, "Octopus! The Most Mysterious Creature in the Sea", Penguin Group, 2013 (we also read that source) en.wikipedia.org
  4. Wikipedia, "Octopus" (CC BY-SA 4.0), which cites: Michel, "Quantitative Analysis of Culture Using Millions of Digitized Books", Science, 2011, p. 176–182; "Octopus", Oxforddictionaries.com, 2014; Peters, Pam (2004). The Cambridge Guide to English Usage. Cambridge: Cambridge University Press. , p. 388.; Fowler, "A Dictionary of Modern English Usage", Wordsworth Editions, 1994, p. 316; Tuckey, "Narrative of an Expedition to Explore the River Zaire", Kirk & Mercein, 1818 (original not read by us) en.wikipedia.org
  5. Wikipedia, "Octopus" (CC BY-SA 4.0), which cites: "Giant Pacific Octopus (Enteroctopus dofleini)", Alaska Department of Fish and Game; Cosgrove, J.A. 1987. Aspects of the Natural History of Octopus dofleini, the Giant Pacific Octopus. MSc Thesis. Department of Biology, University of Victoria (C; Norman, M. 2000. Cephalopods: A World Guide. ConchBooks, Hackenheim. p. 214.; High, "The giant Pacific octopus", Marine Fisheries Review, 1976, p. 17–22; O'Shea, "The giant octopus Haliphron atlanticus (Mollusca: Octopoda) in New Zealand waters", New Zealand Journal of Zoology, 2004, p. 7–13; O'Shea, " en.wikipedia.org
  6. Wikipedia, "Octopus" (CC BY-SA 4.0), which cites: Tramacere, "The morphology and adhesion mechanism of Octopus vulgaris suckers", PLOS ONE, 2013; Kier, "The structure and adhesive mechanism of octopus suckers", Integrative and Comparative Biology, 2002, p. 1146–1153; Carefoot, "Octopuses and Relatives: Locomotion, Crawling", A Snail's Odyssey; Katz, "Feel the light – sight independent negative phototactic response in octopus' arms", Journal of Experimental Biology, 1 January 2021 (original not read by us) en.wikipedia.org
  7. Wikipedia, "Octopus" (CC BY-SA 4.0), which cites: Ruppert, "Invertebrate Zoology", Cengage Learning, 2004; Ruppert, "Invertebrate Zoology", Cengage Learning, 2004; Courage, "Octopus! The Most Mysterious Creature in the Sea", Penguin Group, 2013; Mather, "Octopus: The Ocean's Intelligent Invertebrate", Timber Press, 2010; Wells, "Octopus, Physiology and Behaviour of an Advanced Invertebrate", Springer Science+Business Media, 1978; Byrne, "Does Octopus vulgaris have preferred arms?", Journal of Comparative Psychology, August 2006, p. 198–204; Mather, "Octopus: The Ocean's Intelligent Invertebrat en.wikipedia.org
  8. Wikipedia, "Octopus" (CC BY-SA 4.0), which cites: Ruppert, "Invertebrate Zoology", Cengage Learning, 2004; Courage, "Octopus! The Most Mysterious Creature in the Sea", Penguin Group, 2013 (we also read that source) en.wikipedia.org
  9. Wikipedia, "Octopus" (CC BY-SA 4.0), which cites: Wells, "Octopus, Physiology and Behaviour of an Advanced Invertebrate", Springer Science+Business Media, 1978; Courage, "Octopus! The Most Mysterious Creature in the Sea", Penguin Group, 2013; Schmidt-Nielsen, "Animal Physiology: Adaptation and Environment", Cambridge University Press, 1997, p. 117; Oellermann, "Blue blood on ice: modulated blood oxygen transport facilitates cold compensation and eurythermy in an Antarctic octopod", Frontiers in Zoology, 2015, p. 6; Wells, "Octopus, Physiology and Behaviour of an Advanced Invertebrate", Springe en.wikipedia.org
  10. Wikipedia, "Octopus" (CC BY-SA 4.0), which cites: Carefoot, "Octopuses and Relatives: Locomotion, jet propulsion", A Snail's Odyssey; Wells, "Octopus, Physiology and Behaviour of an Advanced Invertebrate", Springer Science+Business Media, 1978; Wells, "The control of ventilatory and cardiac responses to changes in ambient oxygen tension and oxygen demand in Octopus", The Journal of Experimental Biology, 1995, p. 1717–1727; Wells, "Octopus, Physiology and Behaviour of an Advanced Invertebrate", Springer Science+Business Media, 1978; Schmidt-Nielsen, "Animal Physiology: Adaptation and Environmen en.wikipedia.org
  11. Wikipedia, "Octopus" (CC BY-SA 4.0), which cites: Mather, "Octopus: The Ocean's Intelligent Invertebrate", Timber Press, 2010; Courage, "Octopus! The Most Mysterious Creature in the Sea", Penguin Group, 2013 (we also read that source) en.wikipedia.org
  12. "Finned Deep-sea Octopuses, Grimpoteuthis spp", MarineBio, 18 May 2017. facts only, no text reused. marinebio.org
  13. Norman, "Ask an expert: Are there any freshwater cephalopods?", ABC Science, 16 January 2013. facts only, no text reused. abc.net.au

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Octopus (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

Related entries

Named in this entry

Blue-ringed octopusAkkorokamui

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Sources

Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.

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