Blue-ringed octopus: Difference between revisions

'''Blue-ringed octopuses''',<!-- Do not change this to "octopi". See, thesee talk page for the consensus. --> comprising the [[genus]] '''''Hapalochlaena''''', are four extremely [[venom]]ous [[species]] of [[octopus]] that are found in [[tide pool]]s and [[coral reef]]s in the [[Pacific Ocean|Pacific]] and [[Indian Ocean|Indian]] oceans, from [[Japan]] to [[Australia]].<ref name=tiny/> They can be identified by their yellowish skin and characteristic blue and black rings that [[#Behavior|can change color dramatically]] when the animal is threatened. They eat small [[crustacean]]s, including [[crab]]s, [[hermit crab]]s, [[shrimp]], and other small sea animals.

They are one of the world's most venomous marine animals.<ref>{{cite web |url=http://animal.discovery.com/convergence/oceans-deadliest/deadliest-creatures/deadliest-creatures_05.html |title=Ocean's Deadliest: The Deadliest Creatures – Greater Blue-Ringed Octopus |publisher=[[Animal Planet]] |archive-url=https://web.archive.org/web/20090218092057/http://animal.discovery.com/convergence/oceans-deadliest/deadliest-creatures/deadliest-creatures_05.html |archive-date=2009-02-18 }}</ref> Despite their small size—{{convert|12|to|20|cm|in|abbr=on|0}}—and relatively docile nature, they are very dangerous to [[human]]s if provoked when handled because their venom contains a powerful [[neurotoxin]] called [[tetrodotoxin]].

The blue-ringed octopus often feeds on fish and crustaceans. It pounces on its prey, seizing it with its arms and pulling it towards its mouth. It uses its [[cephalopod beak|horny beak]] to pierce through the tough crab or shrimp [[exoskeleton]], releasing its venom. The venom paralyzes the muscles required for movement, which effectively kills the prey.<ref>{{Cite web |last=Newman |first=Shane |date=2015-05-05 |title=Blue-Ringed Octopus Facts, Habitat, Life Cycle, Venom, Pictures |url=https://www.animalspot.net/blue-ringed-octopus.html |access-date=2023-08-25 |website=Animal Spot |language=en-US}}</ref> The octopus is yellow with dark brown rings while it is at rest, but when agitated, the rings turn into vivid blue. The chromatophores, an assortment of elastic ink-filled sacs found beneath the skin, are responsible for this shift in ink color. When the octopus feels threatened, the chromatophores stretch and the animal's rings turn a bright neon blue. The sac will contract as soon as the danger has passed.

The blue-ringed octopus, despite its small size, carries enough venom to kill 26 adult humans within minutes. Their bites are tiny and often painless, with many victims not realizing they have been [[Envenomation|envenomated]] until [[respiratory depression]] and [[paralysis]] begins.<ref>{{cite web |url=http://www.barrierreefaustralia.com/the-great-barrier-reef/blueringedoctopus.htm |title=Dangers on the Barrier Reef |access-date=2006-12-06 |archive-url=https://web.archive.org/web/20061205092145/http://www.barrierreefaustralia.com/the-great-barrier-reef/blueringedoctopus.htm |archive-date=2006-12-05 }}</ref> No blue-ringed octopus [[antivenom]] is available at the moment.<ref>{{Cite web |url=http://www.toxinology.com/generic_static_files/cslavh_marine.html#blue%2520ringed |title=CSL Antivenom Handbook – Jellyfish and other Marine Animals |website=Clinical Toxinology Resources |publisher=The University of Adelaide |access-date=2018-01-31}}</ref>

The octopus produces venom containing [[tetrodotoxin]], [[histamine]], [[tryptamine]], [[octopamine (drug)|octopamine]], [[taurine]], [[acetylcholine]], and [[dopamine]]. The venom can result in [[nausea]], [[respiratory arrest]], [[heart failure]], severe and sometimes total [[paralysis]], [[blindness]], and can lead to death within minutes if not treated. Death is usually from suffocation due to paralysis of the diaphragm.<ref>{{cite web |last1=Spencer |first1=Erin |url=https://oceanconservancy.org/blog/2017/03/13/the-blue-ringed-octopus-small-but-deadly/ |title=The Blue-Ringed Octopus: Small but Deadly |date=13 March 2017 |website=[[Ocean Conservancy]] |access-date=7 April 2024}}</ref>

The venom is produced in the posterior salivary gland of the octopus by [[Endosymbiont|endosymbiotic bacteria]].<ref>{{cite web |last1=Allan |first1=Bronwyn |title=Blue ringed octopus |url=https://www.aims.gov.au/docs/projectnet/blue-ringed-octopus.html |website=[[Australian Institute of Marine Science]] |access-date=7 April 2024}}</ref><ref>{{cite web |last1=Laidlaw |first1=Shawn |url=https://biologydictionary.net/blue-ringed-octopus/ |title=Blue Ringed Octopus - Facts and Beyond |date=2 October 2020 |website=Biology Dictionary}}</ref><ref>{{cite web |url=http://www.thecephalopodpage.org/bluering2.php |title=What makes blue-rings so deadly? |author=Caldwell, Roy |access-date=2007-03-19}}</ref> The salivary glands possess a [[Tubuloacinar gland|tubuloacinar]] [[exocrine gland|exocrine]] structure and are located in the intestinal blood space.{{fact|date=November 2022}}

The major [[neurotoxin]] component of the blue-ringed octopus is a compound that was originally known as 'maculotoxin'; butin was1978, laterthis maculotoxin was found to be identical to [[tetrodotoxin]],<ref>{{cite journal |vauthors=Sheumack DD, Howden ME, Spence I, Quinn RJ |title=Maculotoxin: a neurotoxin from the venom glands of the octopus ''Hapalochlaena maculosa'' identified as tetrodotoxin |journal=Science |volume=199 |issue=4325 |pages=188–9 |year=1978 |pmid=619451 |doi=10.1126/science.619451 |bibcode=1978Sci...199..188S }}</ref> a neurotoxin also found in [[pufferfish]], [[rough-skinned newt]]s, and some [[poison dart frog]]s; the blue-ringed octopus is the first reported instance in which tetrodotoxin is used as a venom.<ref>{{cite journal |doi= 10.1016/0041-0101(94)90081-7 |author1=Daly, J.W. |author2=Gusovsky, F. |author3=Myers, C.W. |author4=Yotsuyamashita, M. |author5=Yasumoto, T. |name-list-style=amp |title=1st Occurrence of Tetrodotoxin in a Dendrobatid Frog (''Colostethus inguinalis''), with Further Reports for the Bufonid Genus ''Atelopus'' |journal=Toxicon |volume=32 |issue=3 |year=1994 |pages=279–285 |pmid=8016850}}</ref> Tetrodotoxin blocks [[sodium channel]]s, causing [[motor system|motor]] [[paralysis]] and [[respiratory arrest]] within minutes of exposure. The octopus's own sodium channels are adapted to be resistant to tetrodotoxin.<ref>{{Cite journal |last1=Geffeney |first1=Shana L. |last2=Williams |first2=Becky L. |last3=Rosenthal |first3=Joshua J.C. |last4=Birk |first4=Matthew A. |last5=Felkins |first5=Justin |last6=Wisell |first6=Christine M. |last7=Curry |first7=Eveningstar R. |last8=Hanifin |first8=Charles T. |date=2019 |title=Convergent and parallel evolution in a voltage-gated sodium channel underlies TTX-resistance in the Greater Blue-ringed Octopus: Hapalochlaena lunulata |journal=Toxicon |language=en |volume=170 |pages=77–84 |doi=10.1016/j.toxicon.2019.09.013 |pmid=31550451 |s2cid=202761604 |doi-access=free}}</ref> The tetrodotoxin is produced by [[bacteria]] in the [[salivary gland]]s of the octopus.<ref>{{cite web |url=http://www.thecephalopodpage.org/bluering2.php |title=What makes blue-rings so deadly? |author=Caldwell, Roy |access-date=2007-03-19}}</ref>

Estimates of the number of recorded human fatalities caused by blue-ringed octopuses vary, ranging from seven to sixteen deaths; most scholars agree that there have been at least eleven.<ref name=rifkin>{{cite book |last1=Burnett |first1=Joseph W. |last2=Burnett |first2=Joseph |last3=Rifkin |first3=Jacqueline F. |title=Venomous and Poisonous Marine Animals: A Medical and Biological Handbook |date=1996 |publisher=UNSW Press |isbn=978-0-86840-279-6 }}{{pn|date=November 2022}}</ref>

Tetrodotoxin can be found in nearly every organ and gland of its body. Even sensitive areas such as the [[Needham's sac]], [[branchial heart]], nephridia, and gills have been found to contain tetrodotoxin, and it has no effect on the octopus's normal functions.<ref>{{cite journal |author=Caldwell, R. |author2=Stark, Michael |author3=Williams, B. L. | year = 2012 | title = Microdistribution of tetrodotoxin in two species of blue-ringed octopuses (''Hapalochlaena lunulata'' and ''Hapalochlaena fasciata'') detected by fluorescent immunolabeling | journal = Toxicon | volume = 60 | issue = 7 | pages = 1307–1313 | doi = 10.1016/j.toxicon.2012.08.015 | pmid = 22983011 }}</ref> This may be possible through a unique blood transport. The mother will inject the neurotoxin (and perhaps the toxin-producing bacteria) into her eggs to make them generate their own venom before hatching.<ref>{{cite journal |author=Becky L. Williams |author2=Charles T. Hanifin |author3=Edmund D. Brodie Jr. |author4=Roy L. Caldwell | s2cid = 11624429 | year = 2011 | title = Ontogeny of Tetrodotoxin Levels in Blue-ringed octopuses: Maternal Investment and Apparent Independent Production in Offspring of ''Hapalochlaena lunulata'' | journal = Journal of Chemical Ecology | volume = 37 | issue = 1 | pages = 10–17 | doi = 10.1007/s10886-010-9901-4 | pmid = 21165679 |bibcode=2011JCEco..37...10W }}</ref>

In the 1983 [[James Bond]] film ''[[Octopussy]]'', the blue-ringed octopus is the prominent symbol of the secret order of female bandits and smugglers, appearing in an aquarium tank, on silk robes, and as a tattoo on women in the order.<ref>{{cite web |url=https://www.imdb.com/title/tt0086034/trivia |title=Octopussy (1983) |publisher=IMDb}}</ref><ref name=tiny>{{cite web |url=http://www.cbsnews.com/news/tiny-but-deadly-spike-in-blue-ringed-octopus-sightings-sparks-fear-of-invasion-in-japan/ |title=Tiny but deadly: Spike in blue-ringed octopus sightings sparks fear of invasion in Japan |author=Craft, Lucy |publisher=CBS News |date=2013-07-01 |access-date=2018-01-23}}</ref> The animal was also featured in the book ''[[State of Fear]]'' by [[Michael Crichton]], where a terrorist organization utilized the animal's venom as a favored murder weapon. ''[[The Adventure Zone]]'' featured a blue-ringed octopus in its "Petals to the Metal" series.<ref>{{cite web |url=http://www.maximumfun.org/adventure-zone/ep-24-petals-metal-chapter-seven |title=Ep. 24. Petals to the Metal – Chapter Seven |website=Maximum Fun|date=24 September 2015 |access-date=2016-09-19}}</ref>

* {{cite journal |last1=Gibbs |first1=P.J. |last2=Greenaway |first2=P. |title=Histological structure of the posterior salivary glands in the blue ringed octopus ''Hapalochlaena maculosa'' Hoyle |journal=Toxicon |date=January 1978 |volume=16 |issue=1 |pages=59–70 |doi=10.1016/0041-0101(78)90061-2 |pmid=622727 }}