Editing Vampire squid (section)

==Biology==
The vampire squid's [[Cosmopolitan distribution|worldwide range]] is confined to the [[tropics]] and [[subtropics]].<ref>{{cite web |title=Vampyroteithis infernalis |url=https://animaldiversity.org/accounts/Vampyroteuthis_infernalis/#:~:text=The%20vampire%20squid%20lives%20in,where%20virtually%20no%20light%20penetrates. |website=Animal Diversity Web |publisher=University of Michigan |access-date=5 March 2021}}</ref>{{Contradictory inline|reason=Lede states that it is also present in temperate waters|date=October 2024}} This species is an extreme example of a [[deep sea]] cephalopod, thought to reside at [[Aphotic zone|aphotic]] (lightless) depths from {{convert|600|to|900|m}} or more. Within this region of the world's oceans is a discrete [[habitat (ecology)|habitat]] known as the [[oxygen minimum zone]] (OMZ). Within an OMZ, the [[solubility|saturation]] of [[oxygen]] is too low to support aerobic [[metabolism]] in most complex organisms. The vampire squid is the only cephalopod able to live its entire life cycle in the minimum zone, at [[oxygen saturation]]s as low as 3%.

[[File:MBNMS juvenile vampire squid (49041024167).jpg|thumb|Juvenile vampire squid]]
What behavioral data is known has been gleaned from ephemeral encounters with [[remotely operated underwater vehicle]]s (ROV). Vampire squid are frequently injured during capture, and can survive up to two months in [[Aquarium|aquaria]]. It has been hypothesized that they can live for over eight years.{{sfn|Hoving |Laptikhovsky |Robison |2015}}

To cope with life in the suffocating depths, vampire squids have developed several adaptations: Of all deep-sea cephalopods, their mass-specific [[Metabolism|metabolic rate]] is the lowest. Their blue blood's [[hemocyanin]] binds and transports oxygen more efficiently than in other cephalopods,{{sfn|Seibel|Chausson|Lallier|Zal|1999}} aided by [[gill]]s possessing an especially large surface area. The animals have weak musculature and a greatly [[Gladius (cephalopod)|reduced shell]],<ref>[https://www.frontiersin.org/articles/10.3389/fmars.2022.909192/full The evolution of predator avoidance in cephalopods: A case of brain over brawn?]</ref> but maintain agility and buoyancy with little effort because of sophisticated [[statocyst]]s (balancing organs akin to a human's [[inner ear]]){{sfn|Stephens|Young|2009}} and [[ammonium]]-rich gelatinous tissues closely matching the [[density]] of the surrounding seawater. The vampire squid's ability to thrive in OMZs also keeps it safe from [[apex predator]]s that require a large amount of oxygen to live.{{sfn|Hoving|Robison|2012}}

The vampire squid's large eyes and optic lobes (of their brain) may be an adaptation for greater sensitivity to distant bioluminescence; signs of animals, such as prey aggregations or potential mates. This sensitivity is useful when monitoring a vast area of the [[water column]], which is largely featureless at these depths.<ref name="VisBrain"/>

===Antipredator behavior===
Like many deep-sea cephalopods, the vampire squid lacks [[Cephalopod ink|ink]] sacs. This, along with their low metabolic rate, lead to it adapting various alternate methods of defence. If disturbed, it will curl its arms up outwards and wrap them around its body, turning itself inside-out in a way, making itself seem larger and exposing the spiny projections on its tentacles (the cirri). The underside of the cape is heavily pigmented, concealing most of the body's photophores. The glowing arm tips are clustered together far above the animal's head, diverting attack away from critical areas. This [[Anti-predator adaptation|anti-predator behavior]] is dubbed the "pumpkin" or "pineapple" posture.<ref>{{cite web |url= https://www.youtube.com/watch?v=X8oWnbcLI40&t=33s |archive-url= https://ghostarchive.org/varchive/youtube/20211212/X8oWnbcLI40 |archive-date=2021-12-12 |url-status=live |title=What the vampire squid really eats|last=Monterey Bay Aquarium Research Institute (MBARI)|date=26 September 2012|via=YouTube}}{{cbignore}}</ref><ref>{{cite web |title = Vampire Squid Turns "Inside Out" |publisher = National Geographic |date=4 February 2010 |access-date = 3 June 2011 |url=https://www.nationalgeographic.com/science/article/100203-squid-vampire-threatened-video }}</ref> The armtips [[Regeneration (biology)|regenerate]], so if they are bitten off, they can serve as a diversion allowing the animal to escape while its predator is distracted.{{sfn|Robison |Reisenbichler |Hunt |Haddock |2003}}

If highly agitated, it may eject a sticky cloud of bioluminescent mucus containing innumerable orbs of blue light from its arm tips.<ref>{{cite web |title = Vampire Squid |publisher = Aquarium of the Pacific |access-date = 18 February 2025 |url=https://www.aquariumofpacific.org/onlinelearningcenter/species/vampire_squid }}</ref> 
<!-- {{Dubious|date=October 2024|reason=Is there a pore or similar structure on the arm tips that eject the mucus, instead of the siphon being used to blow it at threats (as in other cephalopods)?}} -->
This luminous barrage, which may last nearly 10 minutes, would presumably serve to dazzle would-be predators and allow the vampire squid to disappear into the dark without the need to swim far. The glowing "ink" is also able to stick to the predator, creating what is called the "burglar alarm effect" (making the vampire squid's would-be predator more visible to secondary predators, similar to the [[Atolla jellyfish|''Atolla'' jellyfish]]'s light display). The display is made only if the animal is very agitated, due to the metabolic cost of mucus regeneration.

Their aforementioned bioluminescent "fireworks" are combined with the writhing of glowing arms, along with erratic movements and escape trajectories, making it difficult for a predator to identify the squid itself among multiple sudden targets. The vampire squid's retractile filaments have been suggested to play a larger role in predator avoidance via both detection and escape mechanisms.<ref name=":2"/>

Despite these defence mechanisms, vampire squids have been found among the stomach contents of large [[Pelagic fish#Deep water fish|deepwater fish]], including [[giant grenadier]]s,<ref>{{cite journal |last1=Drazen |first1=Jeffrey C |last2=Buckley |first2=Troy W |last3=Hoff |first3=Gerald R |year=2001 |title=The feeding habits of slope dwelling macrourid fishes in the eastern North Pacific |journal=Deep-Sea Research Part I: Oceanographic Research Papers |volume=48 |issue=3 |pages=909–935 |doi=10.1016/S0967-0637(00)00058-3|bibcode=2001DSRI...48..909D }}</ref> and deep-diving mammals, such as [[whale]]s and [[sea lion]]s.

===Feeding===
Vampire squid have eight arms but lack feeding tentacles (like octopods), and instead use two retractile filaments in order to capture food. These filaments have small hairs on them, made up of many sensory cells, that help them detect and secure their prey. They combine waste with mucus secreted from the suckers to form balls of food. As [[Sedentary lifestyle|sedentary]] generalist feeders, they feed on [[marine snow|detritus]], including the remains of [[gelatinous zooplankton]] (such as [[salp]]s, [[larvacea]]ns, and medusae [[Jellyfish|jellies]]) and complete crustaceans, such as [[copepod]]s, [[ostracod]]s, [[Amphipoda|amphipod]]s, and [[Isopoda|isopod]]s,{{sfn|Hoving|Robison|2012}} as well as faecal pellets of other aquatic organisms that live above.<ref name=":0">{{cite web |first=Hannah |last=Krakauer |url=https://www.newscientist.com/article/dn22299-vampire-squid-from-hell-eats-faeces-to-survive-depths/ |website=[[New Scientist]] |date=26 September 2012 |title=Vampire squid from hell eats faeces to survive depths|access-date=7 May 2018}}</ref><ref>{{cite web|url=https://sta.uwi.edu/fst/lifesciences/sites/default/files/lifesciences/documents/ogatt/Vampyroteuthis_infernalis%20-%20Vampire%20Squid.pdf|title=''Vampyrotheuthis infernalis'' (Vampire Squid)|website=The Online Guide to the Animals of Trinidad and Tobago|publisher=[[University of the West Indies|UWI]]|access-date=24 May 2022}}</ref> Vampire squids also use a unique luring method where they purposefully agitate [[Bioluminescent bacteria|bioluminescent protist]]s in the water as a way to attract larger prey for them to consume.{{sfn|Hoving|Robison|2012}}

The mature vampire squid is also thought to be an opportunistic hunter of larger prey as fish bones and [[fish scale|scale]]s, along with gelatinous plankton, has been recorded in mature vampire squid stomachs.<ref name="Golikov 2019 19099">{{Cite journal |last=Golikov |first=A. V. |title=The first global deep-sea stable isotope assessment reveals the unique trophic ecology of Vampire Squid Vampyroteuthis infernalis (Cephalopoda) |journal=Nature |year=2019 |volume=9 |issue=1 |page=19099 |doi=10.1038/s41598-019-55719-1 |pmid=31836823 |pmc=6910912 |bibcode=2019NatSR...919099G}}</ref>

===Life cycle===
[[File:Vampyroteuthis1.jpg|thumb|Dissected adult (center) and two immature specimens]]
If hypotheses may be drawn from knowledge of other deep-sea cephalopods, the vampire squid likely reproduces slowly by way of a small number of large eggs, or a [[K-selected#K-selection|K-selected]] strategy. Ovulation is irregular and there is minimal energy devotion into the development of the gonad.<ref name=":3"/> Growth is slow, as nutrients are not abundant at depths frequented by the animals. The vastness of their habitat and its sparse population make reproductive encounters a fortuitous event. With [[Semelparity and iteroparity|iteroparity]] often seen in organisms with high adult survival rates, such as the vampire squid, many low-cost reproductive cycles would be expected for the species.{{sfn |Hoving |Laptikhovsky |Robison |2015}}

Reproduction of the vampire squid is unlike any other coleoid cephalopod; the males pass a "packet" of sperm to a female and the female accepts it and stores it in a special pouch inside her mantle. The female may store a male's hydraulically implanted [[spermatophore]] for long periods before she is ready to fertilize her eggs. Once she does, she may need to brood over them for up to 400 days before they hatch. Their reproductive strategy appears to be [[Semelparity and iteroparity|iteroparous]], which is an exception amongst the otherwise semelparous [[Coleoidea]].{{sfn |Hoving |Laptikhovsky |Robison |2015}} During their life, coleoid cephalopods are thought to go through only one reproductive cycle whereas vampire squid have shown evidence of multiple reproductive cycles. After releasing their eggs, new batches of eggs are formed after the female vampire squid returns to resting. This process may repeat up to, and sometimes more than, twenty times in their lifespan. These spawning events happen quite far apart due to the vampire squid's low metabolic rate.<ref name=":3">{{cite journal |last1=Henk-Jan |first1=Hoving |date=20 April 2015 |title=Vampire squid reproductive strategy is unique among coleoid cephalopods |journal= Current Biology |volume=25 |issue=8 |pages=R322–R323 |doi=10.1016/j.cub.2015.02.018 |pmid=25898098 |doi-access=free|bibcode=2015CBio...25.R322H }}</ref>

Few specifics are known regarding the [[ontogeny]] of the vampire squid. Hatchlings are about 8&nbsp;mm in length and are well-developed miniatures of the adults, with some differences: they are transparent, their arms lack webbing, their eyes are smaller proportionally, and their velar filaments are not fully formed.<ref name=":1">{{Cite journal |url=http://biostor.org/reference/74296 |title=Morphological Observations On A Hatchling And A Paralarva Of The Vampire Squid, Vampyroteuthis Infernalis Chun (Mollusca : Cephalopoda) |last=Young |first=R. E. |year=1998 |journal=Proceedings of the Biological Society of Washington |volume=112 |pages=661–666 |via=biostor.org |access-date=2020-02-09}}</ref> Their development progresses through three morphologic forms: the very young animals have a single pair of fins, an [[Paralarva|intermediate form]] has two pairs, and the mature form again has one pair of fins. At their earliest and intermediate phases of development, a pair of fins is located near the eyes; as the animal develops, this pair gradually disappears as the other pair develops.{{sfn|Pickford|1949}} As the animals grow and their surface area to volume ratio drops, the fins are resized and repositioned to maximize gait efficiency. Whereas the young propel themselves primarily by [[jet propulsion#Jet-propelled animals|jet propulsion]], mature adults prefer the more efficient means of flapping their fins.{{sfn|Seibel|Thuesen|Childress|1998}} This unique ontogeny caused confusion in the past, with the varying forms identified as several species in distinct families.{{sfn|Young|2002}}

The hatchlings survive on a generous internal [[yolk]] supply for an unknown period before they begin to actively feed.<ref name=":1"/> The younger animals frequent much deeper waters, feeding on marine snow and [[zooplankton]].<ref name="Golikov 2019 19099"/>