Editing Amblyopsidae

{{Short description|Family of fishes}}
{{Automatic taxobox
| image = Amblyopsis hoosieri 29330.jpg
| image_caption = [[Hoosier cavefish]], ''Amblyopsis hoosieri''
| taxon = Amblyopsidae
| authority = [[Charles Lucien Bonaparte|Bonaparte]], 1846
| subdivision_ranks = Genera
| subdivision =
''[[Amblyopsis]]''<br/>
''[[Chologaster]]''<br/>
''[[Forbesichthys]]''<br/>
''[[Speoplatyrhinus]]''<br/>
''[[Typhlichthys]]''
}}

The '''Amblyopsidae''' are a fish [[Family (biology)|family]] commonly referred to as '''cavefish''', '''blindfish''', or '''swampfish'''. They are small freshwater fish found in the dark environments of [[cave]]s ([[underground lake]]s, pools, [[Subterranean river|rivers]] and [[Subterranean stream|streams]]), [[Spring (hydrology)|springs]] and [[swamp]]s in the eastern half of the United States. Like other [[troglobites]], most amblyopsids exhibit adaptations to these dark environments, including the lack of functional eyes and the absence of [[pigmentation]]. More than 200 species of [[cavefish]]es are known,<ref name=Proudlove2015>{{cite web | author=Proudlove, G.R. | title=Checklist of troglobitic subterranean fishes of the world to February 2015 | url=http://www.cave-registry.org.uk/svn/BiologyData/Subterranean%20fishes%20of%20the%20world/ChecklistWorldFebruary2015.docx | publisher=cave-registry.org.uk | year=2015 | access-date=14 May 2017 }}</ref><ref name=Riesch2015>Riesch, R.; Tobler, M.; and Plath, M. (2015). ''Extremophile Fishes: Ecology, Evolution, and Physiology of Teleosts in Extreme Environments.'' {{ISBN|978-3319133614}}</ref> but only six of these are in the family Amblyopsidae.<ref name=Romero>Romero, A., editor (2001). ''The Biology of Hypogean Fishes.'' Developments in Environmental Biology of Fishes. {{ISBN|978-1402000768}}</ref><ref>{{cite journal | last1 = Chakrabarty | first1 = P. | last2 = Prejean | first2 = J.A. | last3 = Niemiller | first3 = M.L. | year = 2014 | title = The Hoosier cavefish, a new and endangered species (Amblyopsidae, ''Amblyopsis'') from the caves of southern Indiana | journal = ZooKeys | issue = 412 | pages = 41–57 | doi=10.3897/zookeys.412.7245| pmc = 4042695 | pmid=24899861| doi-access = free | bibcode = 2014ZooK..412...41C }}</ref> One of these, ''[[Forbesichthys agassizii]]'', spends time both underground and aboveground. A seventh species in this family, ''[[Chologaster cornuta]]'', is not a cave-dweller but lives in aboveground swamps.<ref name=EoF/>

==Description==
[[File:Forbesichthys agassizii.jpg|thumb|The [[spring cavefish]] (''Forbesichthys agassizii'') spends some time aboveground and its adaptions to an underground habitat are not as extreme as most species in the family]]

Amblyopsids are generally small, the [[northern cavefish]] (largest species in family) reaching up to {{convert|11|cm|in|abbr=on}} in length.<ref>{{FishBase genus | genus = Amblyopsis| month = May | year = 2017}}</ref>

The amblyopsids are probably ancient in origin. Adaptations common to many cavefish include reduced susceptibility to light, pigment loss, or reduction in skin scales,<ref name="Helfman">{{cite book |last1=Helfman |first1=G. |last2=Collette |first3=D. |last3=Facey |last4=Bowen |first4=BW |title=The Diversity of Fishes: Biology, Evolution, and Ecology |year=2009 |url=http://www.blackwellpublishing.com/helfman/ |publisher=Wiley-Blackwell |isbn=978-1-4051-2494-2 }}</ref> as well as development of [[chemoreceptor]]s in the sensory organs of the body surface and the [[lateral line]]. Three species exhibit efficient [[metabolism]] during swimming, as compared with a group of non-cave fish, and many cavefish species exhibit slender bodies adapted to swimming in fast-flowing waters.<ref name="Helfman" />

The cave-dwellers typically lack pigment and are somewhat translucent.<ref name=Romero/> They have a naked, moderately depressed head and an elongated body, covered with small cycloid irregular flakes, with tiny or absent [[pelvic fin]]s. The anal opening is so far forward that it is in the throat region.

The [[premaxilla]], a bone of the upper [[jaw]], is segmented, and the [[vomer]] has no [[teeth]]. They have no [[ventral fin]]s. The lateral line is incomplete, but well developed in some species. Its spine has between 27 and 35 [[vertebrae]].

Externally, they resemble [[killifish]]es in many respects, although their internal anatomy more closely resembles the [[trout-perch]]es, with which they are currently classified.<ref name=EoF>{{cite book |editor1=Paxton, J.R. |editor2=Eschmeyer, W.N. |author= Cohen, Daniel M.|year=1998|title=Encyclopedia of Fishes|publisher= Academic Press|location=San Diego|pages= 129|isbn= 0-12-547665-5}}</ref>

===Eyes===
The name of the family, Amblyopsidae, refers to their eyes (compare [[amblyopia]]). Most in this family are either [[Blind fish|blind]] or can only detect the difference between light and darkness. The true cave-dwellers have only rudimentary eyes, like so many other fauna that live in the dark.<ref name=Romero/>

Although some cave-dwellers have tiny, [[vestigial]] but functional eyes, others, such as the ''[[Amblyopsis]]'' and ''[[Typhlichthys]]'' have no eyes at all. Blindfish do, however, have rows of sensory [[wikt:papillae|papillae]] on their skin, which they use to help navigate.

Similar darkness-adaptive traits can be seen in [[Cavefish#Range and diversity|many fish families]] where members live underground and is known as [[convergent evolution]].<ref name=Romero/><ref name=Rantin2013>Rantin B., and M.E. Bichuette (2013). ''Phototactic behaviour of subterranean Copionodontinae Pinna, 1992 catfishes (Siluriformes, Trichomycteridae) from Chapada Diamantina, central Bahia, northeastern Brazil.'' International Journal of Speleology 41(1): 57–63</ref>

==Distribution==
All members of this family are small and typical of the fresh waters of the eastern and southern regions of the United States. Some live deep in the swamps, and others in the lakes and streams or in caves, significantly the [[Kentucky]] cave system called the [[Mammoth Cave National Park|Mammoth caves]].

Cavefish can only be found in caves that have streams running into them; a cave with no inlets<!-- uncited, random , such as [[Blanchard Springs Caverns]] in [[Arkansas]],--> does not contain cavefish.

==Ecology==
[[File:AlabamaCavefish.jpg|thumb|The [[Alabama cavefish]] (''Speoplatyrhinus poulsoni'') has a tiny range and is very rare]]

Although the cave habitat generally offers a poor food supply, the advantages of the environment include extremely stable conditions, few competitors, and few predators.<ref name="Helfman" />

Since the cave environment is dark, no plant life is performing [[photosynthesis]], and food is mainly introduced from the outside world by other organisms. Limited food leads to low population density, which has been estimated for Amblyopsidae to be only about 0.005 to 0.150 animals per square meter.<ref name="Helfman" />

Cave habitats are vulnerable to changes in the environment such as water pollution and exotic species.<ref name="Helfman" /> The [[Alabama cavefish]] (''Speoplatyrhinus poulsoni''), which live only in the [[Key Cave National Wildlife Refuge|Key Cave]] in Alabama, is listed as [[Critically Endangered]] by the [[IUCN]], the highest risk class.<ref>{{Cite iucn | author = NatureServe | title = ''Speoplatyrhinus poulsoni'' | volume = 2013 | page = e.T20467A19033986 | date = 2013 | doi = 10.2305/IUCN.UK.2013-1.RLTS.T20467A19033986.en | access-date = 13 January 2018}}</ref>

==Life history and behavior==
Cavefish breed only once a year, occupying{{clarify|date=December 2012}} about 10% of the population.<ref name="Helfman" /> Members of the family Amblyopsidae [[Oviparity|lay eggs]]. Uniquely among fish, the genus ''Amblyopsis'' brood their eggs in the [[gill]] chambers (somewhat like [[mouthbrooder]]s). Formerly it was incorrectly speculated that a similar brooding behavior existed in other members of this family, as well as the [[pirate perch]] (''Aphredoderus sayanus'').<ref name=Armbruster2016>{{cite journal | author=Armbruster, J.W. | author2=M.L. Niemiller | author3=P.B. Hart | name-list-style=amp | title=Morphological Evolution of the Cave-, Spring-, and Swampfishes of the Amblyopsidae (Percopsiformes) | journal=Copeia | year=2016 | volume=104 | issue=3 | pages=763–777 | doi=10.1643/ci-15-339| s2cid=53608365 }}</ref><ref>{{cite journal | last1=Fletcher | first1=D.E. | last2=Dakin | first2=E.E. | last3=Porter | first3=B.A. | last4=Avise | first4=J.C. | year=2004 | title=Spawning behavior and genetic parentage in the pirate perch (Aphredoderus sayanus), a fish with an enigmatic reproductive morphology | journal=Copeia | volume=2004 | issue=1 | pages=1–10 | doi=10.1643/ce-03-160r| s2cid=37827490 }}</ref> Cavefish protect their eggs for the longest period of any fish.<ref name="Helfman" />

A rare feature of this family is the forward placement of its [[cloaca]], under the head, anterior to the pelvic fins.<ref name=EoF /> This placement allows the females to place their eggs more precisely, and is present also in other species of the [[Percopsiformes]] order, such as the [[Aphredoderidae]]. They feed on shrimp, [[gammarus]], and arachnids that fall into the water, using vibrations and current changes to seek out their prey.

==See also==
* [[Troglofauna]]

==References==
{{Reflist}}

==External links==
{{Commons category|Amblyopsidae}}
* {{FishBase family | family = Amblyopsidae | month = January | year = 2006}}
* [http://aquatab.net/system/family/16/ AQUATAB.NET]

{{Taxonbar|from=Q884305}}
{{Authority control}}

[[Category:Amblyopsidae| ]]
[[Category:Cave fish]]
[[Category:Euteleostei families]]
[[Category:Taxa named by Charles Lucien Bonaparte]]