Editing Mantis shrimp (section)

== Description ==
[[File:MantisShrimpLyd.jpg|thumb|right|upright|Drawing of a mantis shrimp by [[Richard Lydekker]]. The folded raptorial claws are flanking the carapace.]]
Mantis shrimp typically grow to around {{cvt|10|cm}} in length, while a few species such as the zebra mantis shrimp can reach up to {{cvt|38|cm}}.<ref name=Hawaii>{{cite news |url=http://the.honoluluadvertiser.com/article/2003/Feb/14/ln/ln01a.html |author=James Gonser |work=[[The Honolulu Advertiser]] |date=February 15, 2003 |title=Large shrimp thriving in Ala Wai Canal muck |access-date=July 20, 2006 |archive-date=November 11, 2020 |archive-url=https://web.archive.org/web/20201111193014/http://the.honoluluadvertiser.com/article/2003/Feb/14/ln/ln01a.html |url-status=live }}</ref> A mantis shrimp's [[carapace]] covers only the rear part of the head and the first four segments of the [[thorax]]. Mantis shrimp widely range in colour, with species mostly being shades of brown to having multiple contrasting, vivid colours.
===Claws===
The mantis shrimp's second pair of thoracic appendages is adapted for powerful close-range combat. These claws can accelerate at a rate comparable to that of a [[.22 caliber]] bullet when fired, having around 1500 newtons of force with each swing/attack.<ref>{{cite web | url=https://sites.nd.edu/biomechanics-in-the-wild/2019/03/05/how-the-mantis-shrimp-packs-its-punch/#:~:text=The%20mantis%20shrimp%2C%20a%20six%20inch%20long%20crustacean,around%201500%20newtons%20of%20force%20with%20each%20blow | title=How the Mantis Shrimp Packs its Punch &#124; Biomechanics in the Wild }}</ref> The appendage differences divide mantis shrimp into two main types: those that hunt by impaling their prey with spear-like structures and those that smash prey with a powerful blow from a heavily mineralised club-like appendage. A considerable amount of damage can be inflicted after impact with these robust, hammer-like claws. This club is further divided into three subregions: the impact region, the periodic region, and the striated region. Mantis shrimp are commonly separated into distinct groups (most are categorized as either spearers or smashers but there are some outliers)<ref>{{Cite web |title=Why are Mantis Shrimp so Awesome? |url=https://www.calacademy.org/explore-science/why-are-mantis-shrimp-so-awesome |access-date=2022-07-21 |website=California Academy of Sciences |language=en |archive-date=2022-08-10 |archive-url=https://web.archive.org/web/20220810083818/https://calacademy.org/explore-science/why-are-mantis-shrimp-so-awesome |url-status=live }}</ref> as determined by the type of claws they possess:

* '''Spearers''' are armed with spiny appendages - the spines having barbed tips - used to stab and snag prey. These raptorial appendages resemble those of [[Mantis|praying mantids]], hence the common name of these crustaceans. This is the type found in most mantis shrimp.<ref name="evo">{{cite journal |last1=Anderson |first1=Philip S.L. |last2=Claverie |first2=Thomas |last3=Patek |first3=S.N. |date=2014-07-01 |title=Levers and linkages: mechanical trade-offs in a power-amplified system |url=https://academic.oup.com/evolut/article/68/7/1919/6852628 |journal=Evolution |volume=68 |issue=7 |pages=1919–1933 |doi=10.1111/evo.12407 |pmid=24635148 |access-date=2025-01-08}}</ref>
* '''Smashers''' possess a much more developed club and a more rudimentary spear (which is nevertheless quite sharp and still used in fights between their own kind); the club is used to bludgeon and smash their prey apart. The inner aspect of the terminal portion of the appendage can also possess a sharp edge, used to cut prey while the mantis shrimp swims. This is found in the families Gonodactylidae, Odontodactylidae, Protosquillidae, and Takuidae.<ref name="evo"/>
* '''Spike smashers (hammers or primitive smashers)''': An unspecialized form, found only in the basal family Hemisquillidae. The last segment lacks spines except at the tip, so it is not as effective at spearing but can also be used for smashing.<ref name="evo"/><ref name=":1" /><ref name=":2" /><ref>{{Cite web |title=h_californiensis |url=https://ucmp.berkeley.edu/arthropoda/crustacea/malacostraca/eumalacostraca/royslist/species.php?name=h_californiensis |access-date=2022-07-21 |website=ucmp.berkeley.edu |archive-date=2023-04-18 |archive-url=https://web.archive.org/web/20230418023755/https://ucmp.berkeley.edu/arthropoda/crustacea/malacostraca/eumalacostraca/royslist/species.php?name=h_californiensis |url-status=live }}</ref>
* '''Hatchet''': An unusual, highly derived appendage that only a few species have. This body plan is largely unresearched.<ref name=":1">{{Cite web |title=How mantis shrimp evolved many shapes with same powerful punch |url=https://phys.org/news/2015-02-mantis-shrimp-evolved-powerful.html |access-date=2022-07-21 |website=phys.org |language=en |archive-date=2022-07-21 |archive-url=https://web.archive.org/web/20220721161949/https://phys.org/news/2015-02-mantis-shrimp-evolved-powerful.html |url-status=live }}</ref><ref name=":2">{{Cite web |title=Roy's List of Stomatopods for the Aquarium |url=https://ucmp.berkeley.edu/arthropoda/crustacea/malacostraca/eumalacostraca/royslist/ |access-date=2022-07-21 |website=ucmp.berkeley.edu |archive-date=2022-08-23 |archive-url=https://web.archive.org/web/20220823173035/https://ucmp.berkeley.edu/arthropoda/crustacea/malacostraca/eumalacostraca/royslist/ |url-status=live }}</ref><ref>{{Cite web |title=a_derijardi |url=https://ucmp.berkeley.edu/arthropoda/crustacea/malacostraca/eumalacostraca/royslist/species.php?name=a_derijardi |access-date=2022-07-21 |website=ucmp.berkeley.edu |archive-date=2022-01-31 |archive-url=https://web.archive.org/web/20220131024528/https://ucmp.berkeley.edu/arthropoda/crustacea/malacostraca/eumalacostraca/royslist/species.php?name=a_derijardi |url-status=live }}</ref>

[[File:20220123 stomatopod strike mechanics spearing en.gif|thumb|Strike mechanics and spearing movement of the second [[maxilliped]] (raptorial claw, ballistic claw) of mantis shrimp]]
Both types strike by rapidly unfolding and swinging their [[raptorial]] claws at the prey, and can inflict serious damage on victims significantly greater in size than themselves. In smashers, these two weapons are employed with blinding quickness, with an acceleration of 10,400&nbsp;[[g-force|''g'']] (102,000&nbsp;m/s<sup>2</sup> or 335,000&nbsp;ft/s<sup>2</sup>) and speeds of {{cvt|23|m/s|km/h mph|lk=on}} from a standing start.<ref name="Patek et al">{{cite journal |author=S. N. Patek, W. L. Korff & R. L. Caldwell |year=2004 |journal=[[Nature (journal)|Nature]] |volume=428 |pages=819–820 |title=Deadly strike mechanism of a mantis shrimp |doi=10.1038/428819a |pmid=15103366 |issue=6985 |bibcode=2004Natur.428..819P |s2cid=4324997 |url=https://pateklab.biology.duke.edu/sites/pateklab.biology.duke.edu/files/Pateketal2004Nature.pdf |access-date=2017-05-02 |archive-date=2021-01-26 |archive-url=https://web.archive.org/web/20210126130108/https://pateklab.biology.duke.edu/sites/pateklab.biology.duke.edu/files/Pateketal2004Nature.pdf |url-status=dead}}</ref> Because they strike so rapidly, they generate vapor-filled bubbles in the water between the appendage and the striking surface—known as [[cavitation]] bubbles.<ref name="Patek et al"/> The collapse of these cavitation bubbles produces measurable forces on their prey in addition to the instantaneous forces of 1,500&nbsp;[[Newton (unit)|newtons]] that are caused by the impact of the appendage against the striking surface, which means that the prey is hit twice by a single strike; first by the claw and then by the collapsing cavitation bubbles that immediately follow.<ref name="Patek and Caldwell">{{cite journal |author1=S. N. Patek |author2=R. L. Caldwell |name-list-style=amp |year=2005 |journal=[[Journal of Experimental Biology]] |volume=208 |pages=3655–3664 |title=Extreme impact and cavitation forces of a biological hammer: strike forces of the peacock mantis shrimp |doi=10.1242/jeb.01831 |pmid=16169943 |issue=19 |doi-access=free}}</ref> Even if the initial strike misses the prey, the resulting [[shock wave]] can be enough to stun or kill.

Smashers use this ability to attack [[crab]]s, [[snail]]s, [[rock oyster]]s, and other [[Mollusca|molluscs]], their blunt clubs enabling them to crack the shells of their prey into pieces. Spearers, however, prefer the meat of softer animals, such as [[fish]] and [[cephalopod]]s, which their barbed claws can more easily slice and snag.

The appendages are being studied as a microscale analogue for new macroscale material structures.<ref name=20160601_SD>{{cite news |title=Mantis shrimp inspires next generation of ultra-strong materials |url=https://www.spacedaily.com/reports/Mantis_shrimp_inspires_next_generation_of_ultra_strong_materials_999.html |work=Space Daily |date=June 1, 2016 |access-date=May 13, 2020 |archive-date=May 24, 2021 |archive-url=https://web.archive.org/web/20210524171606/https://www.spacedaily.com/reports/Mantis_shrimp_inspires_next_generation_of_ultra_strong_materials_999.html |url-status=live }}</ref>{{Clarify|date=January 2025}}

===Eyes===
{{Cleanup|section|reason=Section is quite long due to repetitive sections) and its subsections may not be well delineated, and many sections may be too technical/lacking in clarity for the general audience. Might be more appropriate to have separate article on Stomatopod vision|date=January 2025}}
[[File:Odontodactylus scyllarus eyes.jpg|thumb|Close-up of a peacock mantis shrimp showing the structure of the eyes. The three dark spots are [[pseudopupil]]s, indicating the ommatidia that are pointing towards the camera]]
[[File:Mantis shrimp eyes.jpg|thumb|Close up of ''[[Oratosquilla oratoria]]'' eyes]]
The eyes of the mantis shrimp are mounted on mobile [[Eyestalk|stalks]] and can move independently of each other. The extreme mobility allows them to be rotated in all three dimensions, yet the position of their eyes has shown to have no effect on the perception of their surroundings.<ref>{{Cite journal |title=Complex gaze stabilization in mantis shrimp |first1=Ilse M. |last1=Daly |first2=Martin J. |last2=How |first3=Julian C. |last3=Partridge |first4=Nicholas W. |last4=Roberts |date=May 16, 2018 |journal=Proceedings of the Royal Society B: Biological Sciences |volume=285 |issue=1878 |pages=20180594 |doi=10.1098/rspb.2018.0594 |pmid=29720419 |pmc=5966611}}</ref> They are thought to have the most complex eyes in the animal kingdom and have the most complex front-end for any visual system ever discovered.<ref name="PTRSB">{{cite journal |last1=Cronin |first1=Thomas W. |last2=Bok |first2=Michael J. |last3=Marshall |first3=N. Justin |last4=Caldwell |first4=Roy L. |title=Filtering and polychromatic vision in mantis shrimps: themes in visible and ultraviolet vision |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |date=19 February 2014 |volume=369 |issue=1636 |pages=20130032 |doi=10.1098/rstb.2013.0032 |pmid=24395960 |pmc=3886321}}</ref><ref name="Best eyes">{{cite web |last=Franklin |first=Amanda M. |title=Mantis shrimp have the world's best eyes – but why? |publisher=The Conversation |date=September 4, 2013 |access-date=July 5, 2018 |url=https://theconversation.com/mantis-shrimp-have-the-worlds-best-eyes-but-why-17577 |archive-date=July 5, 2018 |archive-url=https://web.archive.org/web/20180705204125/https://theconversation.com/amp/mantis-shrimp-have-the-worlds-best-eyes-but-why-17577 |url-status=live }}</ref><ref>{{cite journal |last=Milius |first=Susan |title=Mantis shrimp flub color vision test |journal=[[Science News]] |year=2012 |volume=182 |issue=6 |pages=11 |jstor=23351000 |doi=10.1002/scin.5591820609}}</ref> 

Each [[compound eye]] is made up of tens of thousands of [[ommatidium|ommatidia]], clusters of photoreceptor cells.<ref name="Best eyes"/> Each eye consists of two flattened hemispheres separated by parallel rows of specialised ommatidia, collectively called the midband. The number of omatidial rows in the midband ranges from two to six.<ref name="PTRSB"/><ref name="Best eyes"/> This divides the eye into three regions. This configuration enables mantis shrimp to see objects that are near the mid-plane of an eye with three parts of the same eye (as can be seen in some photos showing three [[Pseudopupil|pseudopupils]] in one eye). In other words, each eye possesses ''trinocular vision'', and therefore [[depth perception]], for objects near its mid-plane. The upper and lower hemispheres are used primarily for recognition of form and motion, like the eyes of many other crustaceans.<ref name="PTRSB"/>

Compared with the three types of [[photoreceptor cell]] that humans possess in their eyes, the eyes of a mantis shrimp have between 12 and 16 types of photoreceptor cells. Furthermore, some of these stomatopods can tune the sensitivity of their long wavelength colour vision to adapt to their environment.<ref>{{cite journal |last=Cronin |first=Thomas W. |title=Sensory adaptation: Tunable colour vision in a mantis shrimp |journal=Nature |volume=411 |issue=6837 |pages=547–8 |doi=10.1038/35079184 |pmid=11385560 |year=2001 |bibcode=2001Natur.411..547C |s2cid=205017718}}</ref> This phenomenon, called "spectral tuning", is species-specific.<ref>{{cite journal |title=Evolutionary variation in the expression of phenotypically plastic color vision in Caribbean mantis shrimps, genus Neogonodactylus. |journal=Marine Biology |volume=150 |issue=2 |pages=213–220 |doi=10.1007/s00227-006-0313-5 |year=2006 |last1=Cheroske |first1=Alexander G. |last2=Barber |first2=Paul H. |last3=Cronin |first3=Thomas W. |bibcode=2006MarBi.150..213C |url=http://darchive.mblwhoilibrary.org/bitstream/1912/1391/1/CheroskeetalMB2006reprint.pdf |hdl=1912/1391 |s2cid=40203342 |hdl-access=free |access-date=2019-09-02 |archive-date=2024-01-04 |archive-url=https://web.archive.org/web/20240104013921/https://darchive.mblwhoilibrary.org/server/api/core/bitstreams/cb05f806-6948-5234-a382-fa09c4afb279/content |url-status=live }}</ref> Cheroske et al. did not observe spectral tuning in ''[[Neogonodactylus oerstedii]]'', the species with the most monotonous natural photic environment. In ''N. bredini'', a species with a variety of habitats ranging from a depth of 5 to 10 m (although it can be found down to 20 m below the surface), spectral tuning was observed, but the ability to alter wavelengths of maximum absorbance was not as pronounced as in ''N. wennerae'', a species with much higher ecological/photic habitat diversity. The diversity of spectral tuning in Stomatopoda is also hypothesised to be directly linked to mutations in the [[retinal]] binding pocket of the [[opsin]].<ref>{{cite journal |last1=Porter |first1=Megan L. |last2=Bok |first2=Michael J. |last3=Robinson |first3=Phyllis R. |last4=Cronin |first4=Thomas W. |title=Molecular diversity of visual pigments in Stomatopoda (Crustacea) |journal=Visual Neuroscience |date=1 May 2009 |volume=26 |issue=3 |pages=255–265 |doi=10.1017/S0952523809090129 |pmid=19534844 |s2cid=6516816}}</ref>

The huge diversity seen in mantis shrimp photoreceptors likely comes from ancient [[gene duplication]] events.<ref name="OP30" /><ref>{{cite journal |last1=Porter |first1=Megan L. |last2=Speiser |first2=Daniel I. |last3=Zaharoff |first3=Alexander K. |last4=Caldwell |first4=Roy L. |last5=Cronin |first5=Thomas W. |last6=Oakley |first6=Todd H. |year=2013 |title=The Evolution of Complexity in the Visual Systems of Stomatopods: Insights from Transcriptomics. |journal=Integrative and Comparative Biology |volume=53 |issue=1 |pages=39–49 |doi=10.1093/icb/ict060 |pmid=23727979 |doi-access=free}}</ref> One consequence of this duplication is the lack of correlation between opsin transcript number and physiologically expressed photoreceptors.<ref name="OP30" /> One species may have six different opsin genes, but only express one spectrally distinct photoreceptor. Over the years, some mantis shrimp species have lost the ancestral phenotype, although some still maintain 16 distinct photoreceptors and four light filters. Species that live in a variety of photic environments have high selective pressure for photoreceptor diversity, and maintain ancestral phenotypes better than species that live in murky waters or are primarily nocturnal.<ref name="OP30" /><ref>{{cite journal |title=Evolution of anatomical and physiological specialisation in the compound eyes of stomatopod crustaceans. |journal=Journal of Experimental Biology |volume=213}}</ref>

Mantis shrimp can perceive wavelengths of light ranging from [[Ultraviolet#Subtypes|deep ultraviolet]] (300&nbsp;nm) to [[far-red]] (720&nbsp;nm) and [[Polarization (waves)|polarised light]].<ref name="Best eyes"/><ref name="Science">{{cite journal |last1=Thoen |first1=Hanne H. |last2=How |first2=Martin J. |last3=Chiou |first3=Tsyr-Huei |last4=Marshall |first4=Nicholas Justin |date=January 24, 2014 |title=A Different Form of Color Vision in Mantis Shrimp |journal=[[Science (journal)|Science]] |volume=334 |issue=6169 |pages=411–413 |bibcode=2014Sci...343..411T |doi=10.1126/science.1245824 |pmid=24458639 |s2cid=31784941}}</ref> In mantis shrimp in the superfamilies Gonodactyloidea, Lysiosquilloidea, and Hemisquilloidea, the midband is made up of six ommatidial rows. Rows 1 to 4 process colours, while rows 5 and 6 detect [[Circular polarization|circularly]] or [[Linear polarization|linearly polarised light]]. Twelve types of photoreceptor cells are in rows 1 to 4, four of which detect ultraviolet light.<ref name="PTRSB"/><ref name="Best eyes"/><ref name="Science"/><ref>{{cite journal |last1=Marshall |first1=Nicholas Justin |last2=Oberwinkler |first2=Johannes |title=Ultraviolet vision: the colourful world of the mantis shrimp |journal=[[Nature (journal)|Nature]] |date=October 28, 1999 |volume=401 |pages=873–874 |doi=10.1038/44751 |pmid=10553902 |issue=6756 |bibcode=1999Natur.401..873M |s2cid=4360184}}</ref> Despite the impressive range of wavelengths that mantis shrimp have the ability to see, they do not have the ability to discriminate wavelengths less than 25&nbsp;[[nanometre|nm]] apart.{{Clarification needed|reason=How much is this?|date=July 2024}} It is suggested that not discriminating between closely positioned wavelengths allows these organisms to make determinations of its surroundings with little processing delay. Having little delay in evaluating surroundings is important for mantis shrimp, since they are territorial and frequently in combat.<ref name="Science" /> However, some mantis shrimp have been found capable of distinguishing between high-[[color saturation|saturation]] and low-saturation colors.<ref name=":5">{{Cite journal |last1=Streets |first1=Amy |last2=England |first2=Hayley |last3=Marshall |first3=Justin |date=2022-03-15 |title=Colour vision in stomatopod crustaceans: more questions than answers |journal=Journal of Experimental Biology |language=en |volume=225 |issue=6 |doi=10.1242/jeb.243699 |issn=0022-0949 |pmc=9001920 |pmid=35224643|bibcode=2022JExpB.225B3699S }}</ref>

[[File:Mantis Shrimp at the National Aquarium (Baltimore) - July 2017.jpg|thumb|left|Peacock mantis shrimp at the [[National Aquarium (Baltimore)|National Aquarium]]]]
Rows 1 to 4 of the midband are specialised for colour vision, from deep ultraviolet to far red. Their UV vision can detect five different frequency bands in the deep ultraviolet. To do this, they use two photoreceptors in combination with four different colour filters.<ref name= "CurrBioUV">{{cite journal |author1=Michael Bok |author2=Megan Porter |author3=Allen Place |author4=Thomas Cronin |title=Biological Sunscreens Tune Polychromatic Ultraviolet Vision in Mantis Shrimp |journal=[[Current Biology]] |year=2014 |volume=24 |issue=14 |pages=1636–42 |doi=10.1016/j.cub.2014.05.071 |pmid=24998530 |doi-access=free|bibcode=2014CBio...24.1636B }}</ref><ref>[http://www.latimes.com/science/sciencenow/la-sci-sn-mantis-shrimp-20140703-story.html Mantis shrimp wear tinted shades to see UV light] {{Webarchive|url=https://web.archive.org/web/20141122181512/http://www.latimes.com/science/sciencenow/la-sci-sn-mantis-shrimp-20140703-story.html |date=2014-11-22 }}. Latimes.com (2014-07-05). Retrieved on 2015-10-21.</ref> They are currently believed insensitive to infrared light.<ref>{{cite journal |author1=David Cowles |author2=Jaclyn R. Van Dolson |author3=Lisa R. Hainey |author4=Dallas M. Dick |year=2006 |title=The use of different eye regions in the mantis shrimp ''Hemisquilla californiensis'' Stephenson, 1967 (Crustacea: Stomatopoda) for detecting objects |journal=[[Journal of Experimental Marine Biology and Ecology]] |volume=330 |issue=2 |pages=528–534 |doi=10.1016/j.jembe.2005.09.016|bibcode=2006JEMBE.330..528C }}</ref> The optical elements in these rows have eight different classes of visual pigments and the [[rhabdom]] (area of eye that absorbs light from a single direction) is divided into three different [[pigmented layer]]s (tiers), each for different wavelengths. The three tiers in rows 2 and 3 are separated by colour filters (intrarhabdomal filters) that can be divided into four distinct classes, two classes in each row. Each consists of a tier, a colour filter of one class, a tier again, a colour filter of another class, and then a last tier. These colour filters allow the mantis shrimp to see with diverse colour vision. Without the filters, the pigments themselves range only a small segment of the visual spectrum, about 490 to 550&nbsp;nm.<ref name=OP30>{{cite journal |title=The molecular genetics and evolution of colour and polarization vision in stomatopod crustaceans. |journal=Ophthalmic Physiology |volume=30}}</ref> Rows 5 and 6 are also segregated into different tiers, but have only one class of visual pigment, the ninth class, and are specialised for polarisation vision. Depending upon the species, they can detect circularly polarised light, linearly polarised light, or both. A tenth class of visual pigment is found in the upper and lower hemispheres of the eye.<ref name="PTRSB"/>

Some species have at least 16 photoreceptor types, which are divided into four classes (their spectral sensitivity is further tuned by colour filters in the retinas), 12 for colour analysis in the different wavelengths (including six which are sensitive to ultraviolet light<ref name= "CurrBioUV"/><ref name= "Science 6UV">{{cite web |last=DuRant |first=Hassan |date=3 July 2014 |title=Mantis shrimp use 'nature's sunblock' to see UV |url=https://www.science.org/content/article/mantis-shrimp-use-natures-sunblock-see-uv |work=[[sciencemag.org]] |access-date=5 July 2014 |archive-date=25 April 2023 |archive-url=https://web.archive.org/web/20230425094609/https://www.science.org/content/article/mantis-shrimp-use-natures-sunblock-see-uv |url-status=live }}</ref>) and four for analysing polarised light. By comparison, most humans have only four visual pigments, of which three are dedicated to see colour, and human lenses block ultraviolet light. The visual information leaving the [[retina]] seems to be processed into numerous parallel [[data stream]]s leading into the [[brain]], greatly reducing the analytical requirements at higher levels.<ref>{{cite journal |last1=Cronin |first1=Thomas W. |last2=Marshall |first2=Justin |title=Parallel processing and image analysis in the eyes of mantis shrimps |journal=[[The Biological Bulletin]] |volume=200 |issue=2 |pages=177–183 |year=2001 |pmid=11341580 |doi=10.2307/1543312 |jstor=1543312 |s2cid=12381929 |url=https://www.biodiversitylibrary.org/part/11007 |access-date=2021-05-24 |archive-date=2020-06-19 |archive-url=https://web.archive.org/web/20200619133225/https://www.biodiversitylibrary.org/part/11007 |url-status=live }}</ref>

The midband covers only about 5 to 10° of the visual field at any given instant, but like most crustaceans, mantis shrimps' eyes are mounted on stalks. In mantis shrimp, the movement of the stalked eye is unusually free, and can be driven up to 70° in all possible axes of movement by eight eyecup muscles divided into six functional groups. By using these muscles to scan the surroundings with the midband, they can add information about forms, shapes, and landscape, which cannot be detected by the upper and lower hemispheres of the eyes. They can also track moving objects using large, rapid eye movements where the two eyes move independently. By combining different techniques, including movements in the same direction, the midband can cover a very wide range of the visual field.{{Citation needed|date=July 2024}}

==== Polarized light ====
Six species of mantis shrimp have been reported to be able to detect circularly polarised light, which has not been documented in any other animal, and whether it is present across all species is unknown.<ref>{{cite journal |last1=Chiou |first1=Tsyr-Huei |last2=Kleinlogel |first2=Sanja |last3=Cronin |first3=Tom |last4=Caldwell |first4=Roy |last5=Loeffler |first5=Birte |last6=Siddiqi |first6=Afsheen |last7=Goldzien |first7=Alan |last8=Marshall |first8=Justin |title=Circular polarization vision in a stomatopod crustacean |journal=[[Current Biology]] |volume=18 |issue=6 |pages=429–434 |date=March 25, 2008 |doi=10.1016/j.cub.2008.02.066 |pmid=18356053 |s2cid=6925705 |doi-access=free|bibcode=2008CBio...18..429C }}</ref><ref name="Kleinlogel et al">{{cite journal |last1=Kleinlogel |first1=Sonja |last2=White |first2=Andrew |title=The secret world of shrimps: polarisation vision at its best |journal=[[PLoS ONE]] |volume=3 |issue=5 |pages=e2190 |year=2009 |doi=10.1371/journal.pone.0002190 |pmid=18478095 |pmc=2377063 |bibcode=2008PLoSO...3.2190K |arxiv=0804.2162 |doi-access=free}}</ref><ref>{{cite journal |last1=Templin |first1=Rachel M. |last2=How |first2=Martin J. |last3=Roberts |first3=Nicholas W. |last4=Chiou |first4=Tsyr-Huei |last5=Marshall |first5=Justin |title=Circularly polarized light detection in stomatopod crustaceans: a comparison of photoreceptors and possible function in six species |journal=The Journal of Experimental Biology |date=15 September 2017 |volume=220 |issue=18 |pages=3222–3230 |doi=10.1242/jeb.162941 |pmid=28667244 |doi-access=free|hdl=1983/1f1c982f-9a88-4184-b59a-2cebd73ec818 |hdl-access=free }}</ref> They perform this feat by converting circularly polarized light into linearly polarized light via quarter-[[waveplate]]s formed from stacks of [[Microvillus|microvilli]]. Some of their biological quarter-waveplates perform more uniformly over the visual spectrum than any current man-made polarising optics, and this could inspire new types of optical media that would outperform early 21st century [[Blu-ray]] Disc technology.<ref>{{cite journal |title=A biological quarter-wave retarder with excellent achromaticity in the visible wavelength region |last1=Roberts |first1=Nicholas W. |last2=Chiou |first2=Tsyr-Huei |last3=Marshall |first3=Nicholas Justin |last4=Cronin |first4=Thomas W. |journal=[[Nature Photonics]] |volume=3 |issue=11 |pages=641–644 |year=2009 |doi=10.1038/nphoton.2009.189 |bibcode=2009NaPho...3..641R}}</ref><ref>{{cite web |last=Lee |first=Chris |title=A crustacean eye that rivals the best optical equipment |publisher=[[Ars Technica]] |work=Nobel Intent |date=November 1, 2009 |url=https://arstechnica.com/science/news/2009/11/a-crusty-eye-sees-curly-light.ars |access-date=June 14, 2017 |archive-date=April 5, 2012 |archive-url=https://web.archive.org/web/20120405130942/http://arstechnica.com/science/news/2009/11/a-crusty-eye-sees-curly-light.ars |url-status=live }}</ref>

The species ''[[Gonodactylus smithii]]'' is the only organism known to simultaneously detect the four linear and two circular polarisation components required to measure all four [[Stokes parameters]], which yield a full description of polarisation. It is thus believed to have optimal polarisation vision.<ref name="Kleinlogel et al"/><ref>{{cite web |last=Minard |first=Anne |title="Weird beastie" shrimp have super-vision |publisher=[[National Geographic Society]] |date=May 19, 2008 |url=http://news.nationalgeographic.com/news/2008/05/080519-shrimp-colors.html |archive-url=https://web.archive.org/web/20080527213305/http://news.nationalgeographic.com/news/2008/05/080519-shrimp-colors.html |url-status=dead |archive-date=May 27, 2008}}</ref> It is the only animal known to have dynamic polarisation vision. This is achieved by rotational eye movements to maximise the polarisation contrast between the object in focus and its background.<ref>{{Cite journal |last1=Daly |first1=Ilse M. |last2=How |first2=Martin J. |last3=Partridge |first3=Julian C. |last4=Roberts |first4=Nicholas W. |date=2018-05-16 |title=Complex gaze stabilization in mantis shrimp |journal=Proceedings of the Royal Society B: Biological Sciences |volume=285 |issue=1878 |pages=20180594 |doi=10.1098/rspb.2018.0594 |pmc=5966611 |pmid=29720419}}</ref> Since each eye moves independently from the other, it creates two separate streams of visual information.<ref>{{cite web |url=http://www.newsweek.com/mantis-shrimp-have-perfected-eye-roll-better-see-things-we-cant-even-imagine-480162 |title=Mantis shrimp have perfected the eye roll to see things we can't imagine |website=[[Newsweek]] |date=14 July 2016 |access-date=6 February 2017 |archive-date=6 February 2017 |archive-url=https://web.archive.org/web/20170206210222/http://www.newsweek.com/mantis-shrimp-have-perfected-eye-roll-better-see-things-we-cant-even-imagine-480162 |url-status=live }}</ref>

====Suggested advantages of visual system====
[[File:Pseudosquilla.JPG|thumb|left|upright|Close-up of the trinocular vision of ''[[Pseudosquilla ciliata]]'']]
What advantage sensitivity to polarisation confers is unclear; however, polarisation vision is used by other animals for sexual signaling and secret communication that avoids the attention of predators.<ref>{{cite journal |last1=How |first1=M. J. |last2=Porter |first2=M. L. |last3=Radford |first3=A. N. |last4=Feller |first4=K. D. |last5=Temple |first5=S. E. |last6=Caldwell |first6=R. L. |last7=Marshall |first7=N. J. |last8=Cronin |first8=T. W. |last9=Roberts |first9=N. W. |title=Out of the blue: the evolution of horizontally polarized signals in Haptosquilla (Crustacea, Stomatopoda, Protosquillidae) |journal=Journal of Experimental Biology |date=7 August 2014 |volume=217 |issue=19 |pages=3425–3431 |doi=10.1242/jeb.107581 |pmid=25104760 |doi-access=free|hdl=11603/13393 |hdl-access=free }}</ref> This mechanism could provide an evolutionary advantage; it only requires small changes to the cell in the eye and could easily lead to [[natural selection]].<ref>{{cite press release |title=Mantis shrimps could show us the way to a better DVD |publisher=University of Bristol |date=25 October 2009 |url=http://www.bristol.ac.uk/news/2009/6591.html |access-date=May 13, 2020 |archive-date=31 October 2020 |archive-url=https://web.archive.org/web/20201031051957/http://www.bristol.ac.uk/news/2009/6591.html |url-status=live }}</ref>

The eyes of mantis shrimp may enable them to recognise different types of coral, prey species (which are often transparent or semitransparent), or predators, such as [[barracuda]], which have shimmering scales. Alternatively, the manner in which they hunt (very rapid movements of the claws) may require very accurate ranging information, which would require accurate depth perception. The capacity to see UV light may enable observation of otherwise hard-to-detect prey on coral reefs.<ref name= "Science 6UV"/>

During mating rituals, mantis shrimp actively [[fluoresce]], and the wavelength of this fluorescence matches the wavelengths detected by their eye pigments.<ref>{{cite journal |author1=C. H. Mazel |author2=T. W. Cronin |author3=R. L. Caldwell |author4=N. J. Marshall |year=2004 |title=Fluorescent enhancement of signaling in a mantis shrimp |journal=[[Science (journal)|Science]] |volume=303 |issue=5654 |page=51 |doi=10.1126/science.1089803 |pmid=14615546 |s2cid=35009047}}</ref> Females are only fertile during certain phases of the [[Tide|tidal cycle]]; the ability to perceive the [[lunar phase|phase of the moon]] may, therefore, help prevent wasted mating efforts. It may also give these shrimps information about the size of the tide, which is important to species living in shallow water near the shore.{{Citation needed|date=December 2024}}

Researchers suspect that the broader variety of photoreceptors in the eyes of mantis shrimp allows visual information to be preprocessed by the eyes instead of the brain, which would otherwise have to be larger to deal with the complex task of [[opponent process]] colour perception used by other species, thus requiring more time and energy. While the eyes themselves are complex and not yet fully understood, the principle of the system appears to be simple.<ref>{{cite journal |last1=Morrison |first1=Jessica |title=Mantis shrimp's super colour vision debunked |journal=Nature |date=23 January 2014 |doi=10.1038/nature.2014.14578 |s2cid=191386729}}</ref> It has a similar set of sensitivities to the human visual system, but works in the opposite manner. In the human brain, the inferior temporal cortex has a huge number of colour-specific neurons, which process visual impulses from the eyes to extract colour information. The mantis shrimp instead uses the different types of photoreceptors in its eyes to perform the same function as the human brain neurons, resulting in a hardwired and more efficient system for an animal that requires rapid colour identification. Humans have fewer types of photoreceptors, but more colour-tuned neurons, while mantis shrimp appear to have fewer colour neurons and more classes of photoreceptors.<ref>{{cite web |last1=Macknik |first1=Stephen L. |title=Parallels between Shrimp and Human Color Vision |url=https://blogs.scientificamerican.com/illusion-chasers/parallels-between-shrimp-and-human-color-vision/ |website=Scientific American Blog Network |date=March 20, 2014 |access-date=May 13, 2020 |archive-date=May 25, 2020 |archive-url=https://web.archive.org/web/20200525140407/https://blogs.scientificamerican.com/illusion-chasers/parallels-between-shrimp-and-human-color-vision/ |url-status=live }}</ref>

However, a study from 2022 failed to find unequivocal evidence for a solely "barcode"-like visual system as described above. Stomatopods of the species ''Haptosquilla trispinosa'' were able to distinguish high and low-saturation colors from grey, contravening Thoen and colleagues.<ref name=":5" /><ref name="Science" /> It may be that some combination of [[color opponency]] and photoreceptor activation comparison/barcode analysis is present.<ref name=":5" />

The shrimps use a form of reflector of polarised light not seen in nature or human technology before. It allows the manipulation of light across the structure rather than through its depth, the typical way polarisers work. This allows the structure to be both small and microscopically thin, and still be able to produce big, bright, colourful polarised signals.<ref>[http://www.bristol.ac.uk/news/2016/february/mantis-shrimp.html New type of optical material discovered in the secret language of the mantis shrimp] {{Webarchive|url=https://web.archive.org/web/20160307200843/http://bristol.ac.uk/news/2016/february/mantis-shrimp.html |date=2016-03-07 }}. Bristol University (17 February 2016)</ref>