Editing Vampire squid (section)

==Description==
The vampire squid can reach a maximum total length around {{convert|30|cm|ft|0|abbr=on}}. Its {{convert|15|cm|in|adj=on}} gelatinous body varies in colour from velvety jet-black to pale reddish, depending on location and lighting conditions.{{Clarify|reason=Could the chromatophores play a role in this color-shifting?|date=October 2024}} A webbing of skin connects its eight arms, each lined with rows of fleshy spines or [[cirrus (biology)|cirri]]; the inner side of this "cloak" is black. Only the distal halves (farthest from the body) of the arms have suckers. The name of the animal was inspired by its dark colour and cloaklike webbing, rather than its habits — it feeds on [[marine snow|detritus]], not [[Hematophagy|blood]].<ref name="NOAA">{{cite web |title=The vampire squid and the vampire fish |url=https://oceanservice.noaa.gov/facts/vampire-squid-fish.html#:~:text=Its%20huge%2C%20bright%20blue%20eyes,%E2%80%9Cvampire%20squid%20of%20Hell%E2%80%9D! |website=National Ocean Service |access-date=22 December 2023}}</ref><ref>{{cite web |url= http://www.thecephalopodpage.org/vampy.php |title=''Vampyroteuthis infernalis'', Deep-sea Vampire squid |work=The Cephalopod Page |publisher=Dr. James B. Wood |access-date=3 July 2011}}</ref><ref name=":0"/>

[[File:Vampyroteuthis infernalis dorsal view.jpg|thumb|left|Dorsal view]]

Its [[wiktionary:limpid#adjective|limpid]], globular eyes, which appear red or blue, depending on lighting, are proportionately the largest in the animal kingdom, with a {{convert|6|in|cm}} squid possessing eyes {{convert|2.5|cm|in|0|abbr=on}} in diameter.<ref>{{cite web|url= http://www.thecephalopodpage.org/vsfh.php |title=Introducing ''Vampyroteuthis infernalis'', the vampire squid from Hell |work=The Cephalopod Page |publisher=Dr. James B. Wood |access-date=27 April 2012}}</ref> Their large eyes are accompanied by the similarly expanded optic lobes of their brain.<ref name="VisBrain">{{Cite journal|last1=Chung|first1=Wen-Sung|last2=Kurniawan|first2=Nyoman D.|last3=Marshall|first3=N. Justin|date=2021-11-18|title=Comparative brain structure and visual processing in octopus from different habitats|journal=Current Biology|volume=32 |issue=1 |pages=97–110.e4 |language=English|doi=10.1016/j.cub.2021.10.070|issn=0960-9822|pmid=34798049|s2cid=244398601|doi-access=free}}</ref>

[[File:Vampyroteuthis infernalis arms.jpg|thumb|left|Oral view]]

Mature adults have a pair of [[Cephalopod fin|small fins]] projecting from the lateral sides of the [[mantle (mollusc)|mantle]]. These earlike fins serve as the adult's primary means of propulsion: vampire squid [[Aquatic locomotion|move through the water]] by flapping their fins. Their [[Cephalopod beak|beaklike jaws]] are white. Within the webbing are two pouches wherein the tactile velar filaments are concealed. The filaments are analogous to a true squid's [[tentacle]]s, extending well past the [[cephalopod arm|arm]]s; but differ in origin, and represent the pair that was lost by the ancestral octopus.

The vampire squid is almost entirely covered in light-producing organs called [[photophore]]s, capable of producing disorienting flashes of light ranging in duration from fractions of a second to several minutes. The intensity and size of the photophores can also be modulated. Appearing as small, white discs, the photophores are larger and more complex at the tips of the arms and at the base of the two fins, but are absent from the undersides of the caped arms. Two larger, white areas on top of the head were initially believed to also be photophores, but are now identified as [[Simple eyes in invertebrates|photoreceptor]]s.{{Citation needed|date=October 2024}}

The [[chromatophore]]s (pigment organs) common to most [[cephalopod]]s are poorly developed in the vampire squid. The animal is, therefore, incapable of changing its skin colour in the dramatic fashion of shallow-dwelling cephalopods, as such an ability would not be useful at the lightless depths where it lives.

===Systematics===
[[Image:Vampylarge.JPG|thumb|[[Pyritization|Pyritized]] fossil of ''[[Vampyronassa|Vampyronassa rhodanica]]'' from the Lower [[Callovian]] of [[La Voulte-sur-Rhône (lagerstätte)|La Voulte-sur-Rhône]].]]

The Vampyromorphida is the extant sister taxon to all octopuses. Phylogenetic studies of cephalopods using multiple genes and mitochondrial genomes have shown that the Vampyromorphida are the first group of [[Octopodiformes]] to evolutionarily diverge from all others.<ref>{{Cite journal|last1=Uribe|first1=Juan E.|last2=Zardoya|first2=Rafael|date=May 1, 2017|title=Revisiting the phylogeny of Cephalopoda using complete mitochondrial genomes |url=https://academic.oup.com/mollus/article/83/2/133/2967092|journal=Journal of Molluscan Studies|volume=83|issue=2|pages=133–144|doi=10.1093/mollus/eyw052|via=academic.oup.com|doi-access=free|hdl=10261/156228|hdl-access=free}}</ref><ref name="auto2">{{Cite journal|last1=Lindgren|first1=Annie R.|last2=Pankey|first2=Molly S.|last3=Hochberg|first3=Frederick G.|last4=Oakley|first4=Todd H.|date=July 28, 2012|title=A multi-gene phylogeny of Cephalopoda supports convergent morphological evolution in association with multiple habitat shifts in the marine environment|journal=BMC Evolutionary Biology|volume=12|issue=1|pages=129 |doi=10.1186/1471-2148-12-129|pmc=3733422|pmid=22839506 |doi-access=free |bibcode=2012BMCEE..12..129L }}</ref><ref>{{Cite journal |last1=Strugnell |first1=Jan|last2=Nishiguchi|first2=Michele K.|date=November 1, 2007|title=Molecular phylogeny of coleoid cephalopods (Mollusca: Cephalopoda) inferred from three mitochondrial and six nuclear loci: a comparison of alignment, implied alignment and analysis methods|journal=Journal of Molluscan Studies|volume=73|issue=4 |pages=399–410|doi=10.1093/mollus/eym038|doi-access=free}}</ref> The Vampyromorphida is characterized by derived characters such as the possession of photophores and of two velar filaments which are most probably modified arms. It also shares the inclusion of an internal [[Gladius (cephalopod)|gladius]] with other [[Coleoidea|coleoids]], including squid, and eight webbed arms with [[Cirrina|cirrate]] octopods.

''Vampyroteuthis'' shares its eight cirrate arms with the Cirrata, in which lateral cirri, or filaments, alternate with the suckers. ''Vampyroteuthis'' differs in that suckers are present only on the distal half of the arms while cirri run the entire length. In cirrate octopods suckers and cirri run and alternate on the entire length. Also, a close relationship between ''Vampyroteuthis'' and the Jurassic-Cretaceous [[Loligosepiina]] is indicated by the similarity of their gladii, the internal stiffening structure. ''[[Vampyronassa|Vampyronassa rhodanica]]'' from the middle Jurassic [[La Voulte-sur-Rhône (lagerstätte)|La Voulte-sur-Rhône]] of France is considered as one of a vampyroteuthid that shares some characters with ''Vampyroteuthis''.<ref>{{Cite journal |last1=Rowe |first1=Alison J. |last2=Kruta |first2=Isabelle |last3=Landman |first3=Neil H. |last4=Villier |first4=Loïc |last5=Fernandez |first5=Vincent |last6=Rouget |first6=Isabelle |date=2022-06-23 |title=Exceptional soft-tissue preservation of Jurassic Vampyronassa rhodanica provides new insights on the evolution and palaeoecology of vampyroteuthids |journal=Scientific Reports |language=en |volume=12 |issue=1 |pages=8292 |doi=10.1038/s41598-022-12269-3 |pmid=35739131 |pmc=9225997 |bibcode=2022NatSR..12.8292R |issn=2045-2322|doi-access=free }}</ref>

The supposed vampyromorphids from the [[Kimmeridgian]]-[[Tithonian]] (156–146 mya) of [[Solnhofen]], ''[[Plesioteuthis prisca]]'', ''[[Leptotheuthis gigas]]'', and ''[[Trachyteuthis hastiformis]]'', cannot be positively assigned to this group; they are large species (from 35&nbsp;cm in ''P. prisca'' to > 1 m in ''L. gigas'') and show features not found in vampyromorphids, being somewhat similar to the true squids, [[Teuthida]].{{sfn|Fischer|Riou|2002}}