Editing Fiddler crab

{{Short description|Genus of crabs}}
{{Redirect|Uca|other uses|UCA (disambiguation)}}
{{Paraphyletic group
| fossil_range = [[Early Miocene]]-recent<ref>{{cite web |title=''Uca Leach'' 1814 (fiddler crab) |url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=22745&is_real_user=1 |website=PBDB}}</ref>
| image = fiddler crab.jpg
| image_caption = [[Minuca minax|Red-jointed fiddler crab (''Minuca minax'')]]
| auto = yes
| parent = Ocypodidae
| includes =
* [[Gelasiminae]] <small>Miers, 1886</small>
* Ucinae <small>Dana, 1851</small>
}}

The '''fiddler crab''' or '''calling crab''' can be one of the hundred species of semiterrestrial marine [[crabs]] in the family [[Ocypodidae]].<ref name=Rosenberg2019/> These crabs are well known for their extreme sexual dimorphism, where the male crabs have a major claw significantly larger than their minor claw, whilst females claws are both the same size.<ref>Levinton, J. S., Judge, M. L. & Kurdziel, J. P. (1995) Functional differences between the major and minor claws of fiddler crabs (Uca, family Ocypodidae, order Decapoda, Subphylum Crustacea): A result of selection or developmental constraint? ''Journal of Experimental Marine Biology and Ecology, 193''(1-2), 147-160. [https://doi.org/10.1016/0022-0981(95)00115-8 doi: 10.1016/0022-0981(95)00115-8]</ref> The name fiddler crab comes from the appearance of their small and large claw together, looking similar to a fiddle.

A smaller number of [[ghost crab]] and [[mangrove crab]] species are also found in the family Ocypodidae. This entire group is composed of small crabs, the largest being ''Afruca tangeri'' which is slightly over two inches (5&nbsp;cm) across. Fiddler crabs are found along sea beaches and brackish intertidal mud flats, lagoons, swamps, and various other types of brackish or salt-water [[wetlands]]. Whilst fiddler crabs are currently split into two subfamilies of [[Gelasiminae]] and Ucinae, there is still phylogenetic and taxonomical debate as to whether the movement from the overall genus of ‘’Uca’’ to these subfamilies and the separate 11 genera<ref name=Rosenberg2019/>

Like all crabs, fiddler crabs [[molting|shed their shells]] as they grow. If they have lost legs or claws during their present growth cycle, a new one will be present when they molt. If the major claw is lost, males will regenerate one on the same side after their next molt.<ref>Weis, J. S. (2019). On the Other Hand: The Myth of Fiddler Crab Claw Reversal. ''BioScience, 69''(4), 244-246. [https://doi.org/10.1093/biosci/biz011 doi: 10.1093/biosci/biz011]</ref> Newly molted crabs are very vulnerable because of their soft shells. They are reclusive and hide until the new shell hardens.

In a [[controlled experiment|controlled laboratory setting]], fiddler crabs exhibit a constant [[circadian rhythm]] that mimics the ebb and flow of the tides: they turn dark during the day and light at night.<ref>{{Cite web |title=Elements of Ecology |url=https://www.pearson.com/en-us/subject-catalog/p/elements-of-ecology/P200000006836/9780137502165 |access-date=2024-12-11 |website=www.pearson.com}}</ref>

==Ecology and life cycle ==
Fiddler crabs primarily exist upon mudflats, sandy or muddy [[beaches]] as well as salt marshes within [[mangroves]]. Fiddler crabs are found in [[West Africa]], the [[Western Atlantic]], the [[Eastern Pacific]],  [[Indo-Pacific]] and [[Algarve region]] of [[Portugal]]. 

Whilst the fiddler crab is classified as an omnivore, it does present itself as an opportunist and will consume anything with nutritional value.<ref>Zeil, J., Hemmi, J. M. & Backwell, P. R. Y. (2006). Fiddler crabs. ''Current Biology, 16''(2), 40-41. [https://doi.org/10.1016/j.cub.2006.01.012 doi: 10.1016/j.cub.2006.01.012]</ref> The crab will feed through bringing a chunk of sediment to its mouth and sifting through it to extract organic material. This crab will filter out [[algae]], [[microbes]], [[fungus]] or any form of detritus. Once finished consuming all the organic matter from the sediment, these crabs will then deposit them as small sand balls near their burrow. 

Fiddler crabs are thought to potentially act as [[ecosystem engineer]]s within their habitat due to the way they rework the sediment during feeding.<ref>Crane, J. (2015). ''Fiddler crabs of the world: Ocypodidae: genus Uca'' (Vol. 1276). Princeton University Press.</ref> Whilst these crabs do rework the sediment around them, upturning the very top layer and depositing it nearby, there is still debate that exists as to whether this turnover of sediment has any proven difference regarding nutrients and aeration of the sediment.<ref>Michaels, R. E. & Zieman, J. C. (2013). Fiddler crab (''Uca'' spp.) burrows have little effect on surrounding sediment oxygen concentrations. ''Journal of Experimental Marine Biology and Ecology, 448'', 104-113. [https://doi.org/10.1016/j.jembe.2013.06.020 doi: 10.1016/j.jembe.2013.06.020]</ref>

Fiddler crabs are a burrowing species, where within their territory they may possess several burrows. There are two types of [[burrow]]s that the fiddler crabs can build, either breeding burrows or temporary burrows.<ref>Christy, J. H. (1982). Burrow structure and use in the sand fiddler crab, ''Uca pugilator'' (Bosc). ''Animal Behaviour, 30''(3), 687-694. [https://doi.org/10.1016/S0003-3472(82)80139-5 doi: 10.1016/S0003-3472(82)80139-5]</ref> Temporary burrows are constructed by both males and females during high tide periods. These burrows are also constructed at night time when the crabs are no longer feeding and are hiding from predators. Breeding burrows are constructed by solely males, and will be constructed within the area that they have deemed their territory. These breeding burrows are constructed by male crabs  so that the female and male crabs may copulate within the burrow, and the female may deposit and incubate her eggs within this area. Larger males who can more easily defend their territory will often have multiple suitable breeding burrows within their territory to enable them to mate with multiple female crabs.<ref> Mautz, B., Detto, T., Wong, B. B. M., Kokko, H., Jennions, M. D. & Backwell, P. R. Y. (2011). Male fiddler crabs defend multiple burrows to attract additional females. ''Behavioral Ecology, 22''(2), 261–267. [https://doi.org/10.1093/beheco/arq207 doi: 10.1093/beheco/arq207]</ref> Female crabs are found to prefer to mate with males that have the widest burrows, however, [[carapace]] width and claw size does correlate with the width of the burrow, so could be a potential size bias.<ref name="Reaney">Reaney, L. T., & Backwell, P. R. Y. (2007). Temporal constraints and female preference for burrow width in the fiddler crab, Uca mjoebergi. ''Behavioral Ecology and Sociobiology, 61'', 1515-1521. [https://doi.org/10.1007/s00265-007-0383-5 doi: 10.1007/s00265-007-0383-5] </ref> 

Two types of fiddler crabs are found to exist within a given territory, a wandering female or male, and territory-holding male or females.<ref>Peso, M., Curran, E., & Backwell, P. R. Y. (2016). Not what it looks like: mate-searching behaviour, mate preferences and clutch production in wandering and territory-holding female fiddler crabs. ''Royal Society Open Science, 3''(8). [https://doi.org/10.1098/rsos.160339 doi: 10.1098/rsos.160339]</ref> When in a wandering state, this means crabs do not currently occupy a burrow. They will wander in order to look for territory which contains a burrow, or to look for a mate. Wandering females will look for a mate to [[copulate]] with, usually preferring to mate with a male that currently possesses a burrow. The female fiddler carries her eggs in a mass on the underside of her body. She remains in her burrow during a two-week gestation period, after which she ventures out to release her eggs into the receding tide. The larvae remain [[plankton]]ic for a further two weeks.

The mating system of fiddler crabs is thought to be mainly [[polygynous]], where the male crabs will mate with multiple females if they have the opportunity to, however, female fiddler crabs such as the ''Austruca lactea'' are known to also mate with multiple males.<ref>Murai, M., Goshima, S. & Henmi, Y. (1987). Analysis of the mating system of the fiddler crab, ''Uca lactea. Animal behaviour, 35''(5), 1334-1342. [https://doi.org/10.1016/S0003-3472(87)80005-2 doi: 10.1016/S0003-3472(87)80005-2]</ref> 

As they are a species of crustacean, they perform [[ecdysis]], which is the process of moulting. When crabs moult, they produce hormones which trigger the shedding of their [[exoskeleton]] and regeneration of limbs. Moulting is already an extremely stressful time for fiddler crabs, as their shell becomes extremely soft, leaving them vulnerable to predation.<ref>Guyselman, J. B. (1953). An analysis of the molting process in the fiddler crab, ''Uca pugilator. The Biological Bulletin, 104''(2). [https://doi.org/10.2307/1538787 doi: 10.2307/1538787]</ref> When undergoing this moulting cycle, crabs will frequently hide within their burrows to avoid harm. When male crabs are undergoing the moulting process, if they are exposed to other male crabs in high grouping with consistent light, their ability to regenerate limbs will be impaired.<ref>Weiz, J. S. (1976). Effects of environmental factors on regeneration and molting in fiddler crabs. ''The Biological Bulletin, 150''(1). Doi: 10.2307/1540596</ref>

Whilst the crabs major claw does function as a tool for fighting and competition, it also plays a role in [[thermoregulation]]. As the claw is so large, and these crabs live in generally hot territory, so require strategies to keep themselves cool, particularly for wandering males without burrows. The presence of the major claw upon the male helps them keep their body temperature regulated, and decreases the chance of them losing or gaining too much heat in a given time period. The large claw draws away excess body heat from the core of the fiddler crab and allows it to dissipate.<ref>Darnell, M. Z. & Munguia, P. (2011). Thermoregulation as an Alternate Function of the Sexually Dimorphic Fiddler Crab Claw. ''The American Naturalist, 178''(3). [https://doi.org/10.1086/661239 doi: 10.1086/661239]</ref> Heat is found to dissipate significantly faster when male crabs are performing waving at the same time. 

Fiddler crabs come in many different colourations and patterns, and are known to be able to change their colour over time. Fiddler crabs such as the ''[[Tubuca capricornis]]'' are capable of changing their colour rapidly when placed under significant stress.<ref>Detto, T., Henmi, J. M. & Backwell, P. R. Y. (2008). Colouration and Colour Changes of the Fiddler Crab, ‘’Uca capricornis’’: A Descriptive Study. ''PLOS ONE, 3''(2). [https://doi.org/10.1371/journal.pone.0001629 doi: 10.1371/journal.pone.0001629]</ref> When fiddler crabs undergo moulting, they are seen to have reduced colouration after each sequential moult. Female fiddler crabs are traditionally more colourful than male fiddler crabs. Conspicuous colouring in fiddler crabs is dangerous as it increases predation rate, however, sexual selection argues for brightly coloured crabs.<ref>Detto, T. (2007). The fiddler crab Uca mjoebergi uses colour vision in mate choice. ''Proceedings of the Royal Society B, 274''(1627). [https://doi.org/10.1098/rspb.2007.1059 doi: 10.1098/rspb.2007.1059]</ref> Fiddler crabs have finely tuned visual systems that aid in detecting colours of importance, which aid in selecting coloured mates.<ref>Zeil, J. & Hemmi, J. M. (2006). The visual ecology of fiddler crabs. ''The Journal of Comparative Physiology A, 192'', 1-25. {{doi|10.1007/s00359-005-0048-7}}</ref> When given the choice, females prefer to pick males that are more brightly coloured in comparison to dull males.

==Behaviour, competition, and courtship==
[[File:Fiddler crab anatomy-en.svg|thumb|left|General anatomy of a fiddler crab]]
Fiddler crabs live rather brief lives of no more than two years (up to three years in captivity). Male fiddler crabs use many signalling techniques and performances towards females to win over a female to mate.<ref>Pope, D. S. (2000) Testing function of fiddler crab claw waving by manipulating social context. ''Behavioral Ecology and Sociobiology, 47'', 432-437. https://www.jstor.org/stable/4601768</ref> Females choose their mate based on claw size and also quality of the waving display.<ref name="Perez">{{Cite journal |last=Perez |first=Daniela M. |last2=Rosenberg |first2=Michael S. |last3=Pie |first3=Marcio R. |date= |title=The evolution of waving displays in fiddler crabs (Uca spp., Crustacea: Ocypodidae): WAVING BEHAVIOUR IN FIDDLER CRABS |url=https://academic.oup.com/biolinnean/article-lookup/doi/10.1111/j.1095-8312.2012.01860.x |journal=Biological Journal of the Linnean Society |language=en |volume=106 |issue=2 |pages=307–315 |doi=10.1111/j.1095-8312.2012.01860.x}}</ref> 

It is very common for male fiddler crabs to be viewed fighting against one another. Male fiddler crabs fight primarily over females and territory. Whilst fights within fiddler crabs are commonly male against male fights, male fiddler crabs will also fight against female fiddler crabs when there is suitable territory with a burrow that the male wishes to obtain.<ref>Hyatt, G. W. & Salmon, M. (1978). Combat in the Fiddler Crabs ''Uca Pugilator'' and ''U. Pugnax'': a Quantitative Analysis. ‘’Behaviour, 65’’(1-2). 182-211. [https://doi.org/10.1163/156853978X00602 doi: 10.1163/156853978X00602]</ref> When fighting, male fiddler crabs can often have their major claw ripped off, or have it harmed to the point where male fiddler crabs must [[Autotomy|autotomize]] this claw. Whilst this claw can regrow when the crab next moults, the properties of the claw will not be the same as they were previously. Whilst the size of the claw will be the same or similar to how it was before, the claw will become significantly weaker.<ref>Bywater, C. L., Seebacher, F. & Wilson, R. S. (2015). Building a dishonest signal: the functional basis of unreliable signals of strength in males of the two-toned fiddler crab, ''Uca vomeris. The Journal of Experimental Biology, 218''(19), 3077-3082. [https://doi.org/10.1242/jeb.120857 doi: 10.1242/jeb.120857]</ref> Whilst this claw is now significantly weaker, other crabs cannot tell that this claw is weaker, so will assume the claw is at full size and strength. This is a form of dishonest signalling, where the appearance of the claw displayed to other fiddler crabs does not represent the true mechanics of the claw.<ref name=Simon>Lailvaux, S. P., Reaney, L. T. & Backwell, P. R. Y. (2008). Regenerated claws dishonestly signal performance and fighting ability in the fiddler crab ''Uca mjoebergi. Functional Ecology, 23''(2), 359. {{doi|10.1111/j.1365-2435.2008.01501.x}}
</ref>

In order for a male fiddler crab to help produce offspring, he must first attract a mate and convince her to mate with him. To win over females, male crabs will perform a waving display towards females. This waving display consists of raising the major claw upwards and then dropping it down towards itself in what appears as a 'come here' motion, like a [[beckoning sign]].<ref> How, M. J., Zeil, J. & Hemmi, J. M. (2009). Variability of a dynamic visual signal: the fiddler crab claw-waving display. ''Journal of Comparative Physiology A, 195'', 55-67. [https://doi.org/10.1007/s00359-008-0382-7 doi: 10.1007/s00359-008-0382-7] </ref> Male crabs will exhibit two forms of waving towards females to attempt to court them.<ref> How, M. J., Zeil, J. & Hemmi, J. M. (2007). Differences in context and function of two distinct waving displays in the fiddler crab, ''Uca perplexa'' (Decapoda: Ocypodidae).'' Behavioural Ecology and Sociobiology, 62'', 137-148. [https://doi.org/10.1007/s00265-007-0448-5 doi: 10.1007/s00265-007-0448-5]</ref> Broadcast waving is a general wave the male crabs perform when a female crab is not within their field of view. This wave is at a slower pace, as to not use up energy reserves. Directed waving is performed by male crabs when they have spotted a female they wish to mate with. This wave is performed through the male crab facing towards the female, and increasing the pace of the wave towards the female. 
[[File:Uca perplexa male waving.gif|thumb|right|Male lemon-yellow clawed fiddler crab (''[[Austruca perplexa]]''), waving his big claw in display]]

When males are waving at females, this is usually done in [[behavioural synchrony|synchrony]] with other male crabs in the neighbouring area.<ref>Backwell, P., Jennions, M., Wada, K., Murai, M. & Christy, J. (2006). Synchronous waving in two species of fiddler crabs. ''Acta ethologica, 9'', 22–25. [https://doi.org/10.1007/s10211-005-0009-8 doi: 10.1007/s10211-005-0009-8]</ref> Synchronous waving does provide a general positive benefit for male crabs attempting to attract wandering females, as a form of [[cooperative behaviour]]. Synchrony however, does not provide an individual benefit, as females prefer to mate with the male that is leading the synchronous wave. Therefore, synchronous waving is thought to have evolved as an incidental byproduct of males competing to lead the wave.<ref>Backwell, P. R. Y. (2018). Synchronous waving in fiddler crabs: a review. ''Current Zoology, 65''(1), 83-88. [https://doi.org/10.1093/cz/zoy053 doi: 10.1093/cz/zoy053]</ref>

Fiddler crabs are also known to build sedimentary pillars around their burrows out of mud and sand. 49 of the total species under the family Ocypodidae will construct sedimentary pillars outside of their burrows for the purposes of courtship and defense from other crabs.<ref>Pardo, J. C. F., Stefanelli-Silva, G., Christy, J. H. & Costa, T. M. (2020). Fiddler crabs and their above-ground sedimentary structures: a review. ''Journal of Ethology, 38'', 137-154, [https://doi.org/10.1007/s10164-020-00647-1 doi: 10.1007/s10164-020-00647-1]</ref> These structures can be built by either male or female crabs and will be one of the six known structures constructed by fiddler crabs. Fiddler crabs can build either a chimney, hood, pillar, semidome, mudball or rim. These mud pillars have correlations with sediment type, genus and sex. Females are more likely to be attracted to a male if he has a sedimentary pillar outside of his burrow in comparison to a male crab without a pillar. When females are not actively being courted, they are more likely to move to an empty burrow which has a pillar present in comparison to an empty burrow without a pillar present.<ref>Christy, J. (1988). Pillar Function in the Fiddler Crab ''Uca beebei'' (II):Competitive Courtship Signaling. ''Ethology, 78''(2), 89-176. [https://doi.org/10.1111/j.1439-0310.1988.tb00223.xopen_in_newISSN doi: 10.1111/j.1439-0310.1988.tb00223.xopen_in_newISSN]</ref> Fiddler crabs with any hood or dome formed pillar above their burrow are more likely to be [[shy]] crabs that take less risks. 

Female crabs will choose their mate based upon the claw size of the male, as well as the quality of the waving display, if he was the leader of the synchronous waving, and if the male currently possesses territory with a burrow for them to copulate within.<ref name=Perez/> Females will also prefer to mate with males who have the widest and largest burrows. 

[[File:Fiddler Crabs Fighting in Belle Hall, Mount Pleasant, South Carolina on March 24, 2023.jpg|thumb|Fiddler crabs fighting in Belle Hall, Mount Pleasant, South Carolina in March 2023]]

Fiddler crabs such as ''[[Austruca mjoebergi]]'' have been shown to bluff about their fighting ability. Upon regrowing a lost claw, a crab will occasionally regrow a weaker claw that nevertheless intimidates crabs with smaller but stronger claws.<ref>British Ecological Society. (2008). [http://www.science.unsw.edu.au/news/fiddler-crabs-reveal-honesty-is-not-always-the-best-policy ''Fiddler crabs reveal honesty is not always the best policy''].</ref> This is an example of dishonest [[Signalling theory|signalling]].

The dual functionality of the major claw of fiddler crabs has presented an evolutionary conundrum in that the claw mechanics best suited for fighting do not match up with the mechanics best suited for a waving display.<ref>Swanson, B. O., George, M. N., Anderson, S. P. & Christy, J. H. (2013). Evolutionary variation in the mechanics of fiddler crab claws. ''Bmc Evolutionary Biology, 13'', 137. [https://doi.org/10.1186/1471-2148-13-137 doi: 10.1186/1471-2148-13-137]</ref>

==Genera and species==
More than 100 species of fiddler crabs make up 11 of the 13 genera in the crab family [[Ocypodidae]]. These were formerly members of the genus ''Uca''. In 2016, most of the subgenera of ''Uca'' were elevated to genus rank, and the fiddler crabs now occupy 11 genera making up the subfamilies [[Gelasiminae]] and Ucinae.<ref>Shih, H. T. & Ng, P. K. L., Davie, P. J. F., Schubart, C. D., Türkay, M., Naderloo, R., Jones, D. & Liu, M. (2016). Systematics of the family Ocypodidae Rafinesque, 1815 (Crustacea: Brachyura), Based on phylogenetic relationships, With a reorganization of subfamily rankings and a review of the taxonomic status of Uca Leach, 1814, Sensu lato and its subgenera. ''The Raffles Bulletin of Zoology, 64'', 139-175. [https://dx.doi.org/10.5281/zenodo.5355087 doi: 10.5281/zenodo.5355087]</ref><ref name=Rosenberg2019/><ref name=Ng2008/>

* ''[[Afruca]]''
** ''[[Afruca tangeri]]'' <small>(Eydoux, 1835)</small> (West African fiddler crab)
* ''[[Austruca]]''
** ''[[Austruca albimana]]'' <small>(Kossmann, 1877)</small> (white-handed fiddler crab)
** ''[[Austruca annulipes]]'' <small>([[Henri Milne-Edwards|H.Milne Edwards]], 1837)</small> (ring-legged fiddler crab)
** ''[[Austruca bengali]]'' (bengal fiddler crab)
** ''[[Austruca citrus]]'' (citrus fiddler crab)
** ''[[Austruca cryptica]]'' <small>(Naderloo, Türkay & Chen, 2010)</small> (cryptic fiddler crab)
** ''[[Austruca iranica]]'' <small>(Pretzmann, 1971)</small> (iranian fiddler crab)
** ''[[Austruca lactea]]'' <small>(De Haan, 1835)</small> (milky fiddler crab)
** ''[[Austruca mjoebergi]]'' <small>(Rathbun, 1924)</small> (banana fiddler crab)
** ''[[Austruca occidentalis]]'' <small>(Naderloo, Schubart & Shih, 2016)</small> (East African fiddler crab)
** ''[[Austruca perplexa]]'' <small>([[Henri Milne-Edwards|H.Milne Edwards]], 1852)</small> (perplexing fiddler crab)
** ''[[Austruca sindensis]]'' <small>(Alcock, 1900)</small> (indus fiddler crab)
** ''[[Austruca triangularis]]'' <small>(A.Milne-Edwards, 1873)</small> (triangular fiddler crab)
** ''[[Austruca variegata]]'' <small>(Heller, 1862)</small> (motley fiddler crab)
* ''[[Cranuca]]''
** ''[[Cranuca inversa]]'' <small> (Hoffmann, 1874)</small>
* ''[[Gelasimus]]''
** ''[[Gelasimus borealis]]'' <small>([[Jocelyn Crane|Crane]], 1975)</small> (northern calling fiddler crab)
** ''[[Gelasimus dampieri]]'' <small>([[Jocelyn Crane|Crane]], 1975)</small> (dampier's fiddler crab)
** ''[[Gelasimus excisa]]'' (eastern calling fiddler crab)
** ''[[Gelasimus hesperiae]]'' <small>([[Jocelyn Crane|Crane]], 1975)</small> (western calling fiddler crab)
** ''[[Gelasimus jocelynae]]'' <small>(Shih, Naruse & Ng, 2010) (jocelyn's fiddler crab)</small><ref name=jocelyn/>
** ''[[Gelasimus neocultrimanus]]'' <small>(Bott, 1973)</small>
** ''[[Gelasimus palustris]]'' <small>Stimpson, 1862</small>
** ''[[Gelasimus pugilator]]'' <small>Stimpson, 1862</small>
** ''[[Gelasimus rubripes]]'' <small>Hombron & Jacquinot, 1846</small>
** ''[[Gelasimus subeylindricus]]'' <small>Stimpson, 1862</small>
** ''[[Gelasimus tetragonon]]'' <small>(Herbst, 1790)</small> (tetragonal fiddler crab)
** ''[[Gelasimus vocans]]'' <small>(Linnaeus, 1758)</small> (calling fiddler crab)
** ''[[Gelasimus vomeris]]'' <small>(McNeill, 1920)</small> (orange-clawed fiddler crab)
* ''[[Leptuca]]''
** ''[[Leptuca batuenta]]'' <small>([[Jocelyn Crane|Crane]], 1941)</small> (beating fiddler crab)
** ''[[Leptuca beebei]]'' <small>([[Jocelyn Crane|Crane]], 1941)</small> (Beebe's fiddler crab)
** ''[[Leptuca coloradensis]]'' <small>(Rathbun, 1893)</small> (painted fiddler crab)
** ''[[Leptuca crenulata]]'' <small>(Lockington, 1877)</small> (Mexican fiddler crab)
** ''[[Leptuca cumulanta]]'' <small>([[Jocelyn Crane|Crane]], 1943)</small> (heaping fiddler crab)
** ''[[Leptuca deichmanni]]'' <small>(Rathbun, 1935)</small> (Deichmann's fiddler crab)
** ''[[Leptuca dorotheae]]'' <small>(von Hagen, 1968)</small> (Dorothy's fiddler crab)
** ''[[Leptuca festae]]'' <small>(Nobili, 1902)</small> (Festa's fiddler crab)
** ''[[Leptuca helleri]]'' <small>(Rathbun, 1902)</small> (Heller's fiddler crab)
** ''[[Leptuca inaequalis]]'' <small>(Rathbun, 1935)</small> (uneven fiddler crab)
** ''[[Leptuca latimanus]]'' <small>(Rathbun, 1893)</small> (lateral-handed fiddler crab)
** ''[[Leptuca leptodactyla]]'' <small>(Rathbun, 1898)</small> (thin-fingered fiddler crab)
** ''[[Leptuca limicola]]'' <small>([[Jocelyn Crane|Crane]], 1941)</small> (Pacific mud fiddler crab)
** ''[[Leptuca musica]]'' <small>(Rathbun, 1914)</small> (musical fiddler crab)
** ''[[Leptuca oerstedi]]'' <small>(Rathbun, 1904)</small> (aqua fiddler crab)
** ''[[Leptuca panacea]]'' <small>(Novak & Salmon, 1974)</small> (gulf sand fiddler crab)
** ''[[Leptuca pugilator]]'' <small>(Bosc, 1802)</small> (Atlantic sand fiddler crab)
** ''[[Leptuca pygmaea]]'' <small>([[Jocelyn Crane|Crane]], 1941)</small> (pygmy fiddler crab)
** ''[[Leptuca saltitanta]]'' <small>([[Jocelyn Crane|Crane]], 1941)</small> (energetic fiddler crab)
** ''[[Leptuca speciosa]]'' <small>(Ives, 1891)</small> (brilliant fiddler crab)
** ''[[Leptuca spinicarpa]]'' <small>(Rathbun, 1900)</small> (spiny-wristed fiddler crab)
** ''[[Leptuca stenodactylus]]'' <small>([[Henri Milne-Edwards|Milne-Edwards]] & Lucas, 1843)</small> (narrow-fingered fiddler crab)
** ''[[Leptuca subcylindrica]]'' <small>(Stimpson, 1859)</small> (Laguna Madre fiddler crab)
** ''[[Leptuca tallanica]]'' <small>(von Hagen, 1968)</small> (Peruvian fiddler crab)
** ''[[Leptuca tenuipedis]]'' <small>([[Jocelyn Crane|Crane]], 1941)</small> (slender-legged fiddler crab)
** ''[[Leptuca terpsichores]]'' <small>([[Jocelyn Crane|Crane]], 1941)</small> (dancing fiddler crab)
** ''[[Leptuca thayeri]]'' <small>M. J. Rathbun, 1900</small> (Atlantic mangrove fiddler crab)
** ''[[Leptuca tomentosa]]'' <small>([[Jocelyn Crane|Crane]], 1941)</small> (matted fiddler crab)
** ''[[Leptuca umbratila]]'' <small>([[Jocelyn Crane|Crane]], 1941)</small> (Pacific mangrove fiddler crab)
** ''[[Leptuca uruguayensis]]'' <small>(Nobili, 1901)</small> (Uruguayan fiddler crab)
* ''[[Minuca (crab)|Minuca]]''
** ''[[Minuca argillicola]]'' <small>([[Jocelyn Crane|Crane]], 1941)</small> (clay fiddler crab)
** ''[[Minuca brevifrons]]'' <small>(Stimpson, 1860)</small> (narrow-fronted fiddler crab)
** ''[[Minuca burgersi]]'' <small>(Holthuis, 1967)</small> (burger's fiddler crab)
** ''[[Minuca ecuadoriensis]]'' <small>(Maccagno, 1928)</small> (Pacific hairback fiddler crab)
** ''[[Minuca galapagensis]]'' (galápagos fiddler crab)
** ''[[Minuca herradurensis]]'' <small>(Bott, 1954)</small> (la herradura fiddler crab)
** ''[[Minuca longisignalis]]'' <small>(Salmon & Atsaides, 1968)</small> (longwave gulf fiddler)
** ''[[Minuca marguerita]]'' <small>(Thurman, 1981)</small> (olmec fiddler crab)
** ''[[Minuca minax]]'' <small>(Le Conte, 1855)</small> (red-jointed fiddler crab)
** ''[[Minuca mordax]]'' <small>(Smith, 1870)</small> (biting fiddler crab)
** ''[[Minuca osa]]'' <small>(Landstorfer & Schubart, 2010)</small> (osa fiddler crab)
** ''[[Minuca pugnax]]'' <small>(S. I. Smith, 1870)</small> (Atlantic marsh fiddler crab)
** ''[[Minuca rapax]]'' <small>(Smith, 1870)</small> (mudflat fiddler crab)
** ''[[Minuca umbratila]]'' <small>[[Jocelyn Crane|Crane]], 1941</small> (Pacific mangrove fiddler crab)
** ''[[Minuca victoriana]]'' <small>(von Hagen, 1987)</small> (victorian fiddler crab)
** ''[[Minuca virens]]'' <small>(Salmon & Atsaides, 1968)</small> (green-banded fiddler crab)
** ''[[Minuca vocator]]'' <small>(Herbst, 1804)</small> (Atlantic hairback fiddler crab)
** ''[[Minuca zacae]]'' <small>([[Jocelyn Crane|Crane]], 1941)</small> (lesser Mexican fiddler crab)
* ''[[Paraleptuca]]''
** ''[[Paraleptuca boninensis]]'' <small>(Shih, Komai & Liu, 2013)</small> (bonin islands fiddler crab)
** ''[[Paraleptuca chlorophthalmus]]'' <small>([[Henri Milne-Edwards|H.Milne Edwards]], 1837)</small> (green-eyed fiddler crab)
** ''[[Paraleptuca crassipes]]'' <small>(White, 1847)</small> (thick-legged fiddler crab)
** ''[[Paraleptuca splendida]]'' <small>(Stimpson, 1858)</small> (splendid fiddler crab)
* ''[[Petruca]]''
** ''[[Petruca panamensis]]'' <small>Ng, Shih & Christy, 2015</small>
* ''[[Tubuca]]''
** ''[[Tubuca acuta]]'' <small>(Stimpson, 1858)</small> (acute fiddler crab)
** ''[[Tubuca alcocki]]'' <small>Shih, Chan & Ng, 2018</small> (alcock's fiddler crab)<ref name=Edwards2018/>
** ''[[Tubuca arcuata]]'' <small>(De Haan, 1835)</small> (bowed fiddler crab)
** ''[[Tubuca australiae]]'' <small>([[Jocelyn Crane|Crane]], 1975)</small>
** ''[[Tubuca bellator]]'' <small>(White, 1847)</small> (belligerent fiddler crab)
** ''[[Tubuca capricornis]]'' <small>([[Jocelyn Crane|Crane]], 1975)</small> (capricorn fiddler crab)
** ''[[Tubuca coarctata]]'' <small>([[Henri Milne-Edwards|H.Milne Edwards]], 1852)</small> (compressed fiddler crab)
** ''[[Tubuca demani]]'' <small>(Ortmann, 1897)</small> (demanding fiddler crab)
** ''[[Tubuca dussumieri]]'' <small>([[Henri Milne-Edwards|H.Milne Edwards]], 1852)</small> (dussumier's fiddler crab)
** ''[[Tubuca elegans]]'' <small>(George & Jones, 1982)</small> (elegant fiddler crab)
** ''[[Tubuca flammula]]'' <small>([[Jocelyn Crane|Crane]], 1975)</small> (flame-backed fiddler crab)
** ''[[Tubuca forcipata]]'' <small>(Adams & White, 1849)</small> (forceps fiddler crab)
** ''[[Tubuca hirsutimanus]]'' <small>(George & Jones, 1982)</small> (hairy-handed fiddler crab)
** ''[[Tubuca longidigitum]]'' <small>(Kingsley, 1880)</small> (long-fingered fiddler crab)
** ''[[Tubuca paradussumieri]]'' <small>(Bott, 1973)</small> (spined fiddler crab)
** ''[[Tubuca polita]]'' <small>([[Jocelyn Crane|Crane]], 1975)</small> (polished fiddler crab)
** ''[[Tubuca rhizophorae]]'' <small>(Tweedie, 1950)</small> (Asian mangrove fiddler crab)
** ''[[Tubuca rosea]]'' <small>(Tweedie, 1937)</small> (rose fiddler crab)
** ''[[Tubuca seismella]]'' <small>([[Jocelyn Crane|Crane]], 1975)</small> (shaking fiddler crab)
** ''[[Tubuca signata]]'' <small>(Hess, 1865)</small> (signaling fiddler crab)
** ''[[Tubuca typhoni]]'' <small>([[Jocelyn Crane|Crane]], 1975)</small> (typhoon fiddler crab)
** ''[[Tubuca urvillei]]'' <small>([[Henri Milne-Edwards|H.Milne Edwards]], 1852)</small> (d'urville's fiddler crab)
* ''Uca''
** †''[[Uca antiqua]]'' <small>Brito, 1972</small>
** ''[[American Red Fiddler Crab|Uca heteropleura]]'' <small>(Smith, 1870)</small> (American Red fiddler crab)
** †''[[Uca inaciobritoi]]'' <small>Martins-Neto, 2001</small>
** ''[[Uca insignis]]'' <small>([[Henri Milne-Edwards|H.Milne Edwards]], 1852)</small> (distinguished fiddler crab)
** ''[[Uca intermedia]]'' <small>von Prahl & Toro, 1985</small> (intermediate fiddler crab)
** ''[[Uca major]]'' <small>Herbst, 1782</small> (greater fiddler crab)
** †''[[Uca marinae]]'' <small>Dominguez-Alonso, 2008</small>
** ''[[Uca maracoani]]'' <small>Latreille 1803</small> (Brazilian fiddler crab)
** ''[[Uca monilifera]]'' <small>Rathbun, 1914</small> (necklaced fiddler crab)
** †''[[Uca nitida]]'' <small>Desmarest, 1822</small>
** †''[[Uca oldroydi]]'' <small>Rathbun, 1926</small>
** ''[[Uca ornata]]'' <small>(Smith, 1870)</small> (ornate fiddler crab)
** ''[[Uca princeps]]'' <small>(Smith, 1870)</small> (large Mexican fiddler crab)
** ''[[Uca stylifera]]'' <small>([[Henri Milne-Edwards|H.Milne Edwards]], 1852)</small> (styled fiddler crab)
** ''[[Uca subcylindrica]]'' <small>Stimpson, 1862</small> (Laguna Madre fiddler)
* ''[[Xeruca]]''
** ''[[Xeruca formosensis]]'' <small>(Rathbun, 1921)</small>

==Gallery==
{{Gallery
|title=
|width= | height=
|align=center
|File:Compressed fiddler crab (Uca coarctata) male.jpg
 |alt1=
 |Compressed fiddler crab<br/>''Tubuca coarctata'' male in [[Rinca]], [[Indonesia]]
|File:Boca-cava-terra.jpg 
 |alt2=
 |''[[Afruca tangeri]]''
|File:Uca leptodactyla in Margarita Island.jpg
 |alt3=
 |''Leptuca leptodactyla'' in El Guamache, [[Margarita Island]], [[Venezuela]]
|File:Uca chlorophthalmus - Ogamijima - Okinawa - 2020 3 25.webm
 |alt4=Video of several red and black fiddler crabs in Okinawa
 |''[[Paraleptuca chlorophthalmus]]'' - [[Okinawa Prefecture|Okinawa]], [[Japan]]
|File:Fiddler crab mobius strip.gif
 |alt5=
 |The obvious [[asymmetry]] of male fiddler crabs makes them useful figures in illustrating the non-[[orientability]] of certain geometric objects, like the [[Möbius strip]] shown here.
}}

==Captivity==
Fiddler crabs are occasionally kept as pets.<ref name="McLeod">{{cite web |author=Lianne McLeod |title=How to Set Up a Tank for Fiddler Crabs |url=http://exoticpets.about.com/cs/rarespecies/a/fiddlercrabs.htm |access-date=January 13, 2010 |publisher=[[About.com]] |archive-date=September 29, 2011 |archive-url=https://web.archive.org/web/20110929185857/http://exoticpets.about.com/cs/rarespecies/a/fiddlercrabs.htm |url-status=dead }}</ref> The fiddler crabs sold in pet stores generally come from brackish water lagoons. Because they live in lower salinity water, pet stores may call them fresh-water crabs, but they cannot survive indefinitely in fresh water.<ref name="McLeod"/> Fiddler crabs have been known to attack small fish in captivity, as opposed to their natural feeding habits.<ref>{{Cite web|last=Robert|date=2019-02-22|title=The Complete Fiddler Crab Care Guide: Tank, Food, Facts and More…|url=https://www.fishkeepingworld.com/fiddler-crab/|access-date=2021-04-21|website=Fishkeeping World|language=en-US}}</ref>

==See also==
*[[Declawing of crabs]]

==References==
{{Reflist|2|refs=
<ref name=jocelyn>
{{cite journal |author1=Hsi-Te Shih |author2=Tohru Naruse |author3=Peter K. L. Ng |year=2010 |title=''Uca jocelynae'' sp. nov., a new species of fiddler crab (Crustacea: Brachyura: Ocypodidae) from the Western Pacific |journal=[[Zootaxa]] |volume=2337 |pages=47–62 |url=http://www.mapress.com/zootaxa/2010/f/z02337p062f.pdf |doi=10.11646/zootaxa.2337.1.4 }}</ref>

<ref name=Edwards2018>{{cite journal |url=https://zookeys.pensoft.net/articles.php?id=23468 |title=Tubuca alcocki, a new pseudocryptic species of fiddler crab from the Indian Ocean, sister to the southeastern African T. urvillei (H. Milne Edwards, 1852) |issue=747 |pages=41–62 |journal=ZooKeys |date=29 March 2018 |doi=10.3897/zookeys.747.23468 |access-date=3 April 2018|doi-access=free |last2=Chan |first2=Benny K. K. |last3=Ng |first3=Peter K. L. |pmid=29674902 |last1=Shih |first1=H. T. |pmc=5904522 }}</ref>

<ref name=Ng2008>{{cite journal|journal=[[Raffles Bulletin of Zoology]] |year=2008 |volume=17 |pages=1–286 |title=Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world |author1=Peter K. L. Ng |author2=Danièle Guinot |author3=Peter J. F. Davie |url=http://rmbr.nus.edu.sg/rbz/biblio/s17/s17rbz.pdf |url-status=dead |archive-url=https://web.archive.org/web/20110606061453/http://rmbr.nus.edu.sg/rbz/biblio/s17/s17rbz.pdf |archive-date=2011-06-06 }}</ref>



<ref name=Rosenberg2019>Rosenberg, M. S. (2019). A fresh look at the biodiversity lexicon for fiddler crabs (Decapoda: Brachyura: Ocypodidae). Part 1: Taxonomy. ''Journal of Crustacean Biology, 39''(6), 729-738. [https://doi.org/10.1093/jcbiol/ruz057 doi: 10.1093/jcbiol/ruz057]
</ref>
}}

==External links==
* {{Commons category-inline|Uca}}
* [http://zoo.zool.kyoto-u.ac.jp/ethol/mov/04/0402/momo040225ul01.mov Movie of two fiddler crabs (''Uca lactea lactea'') waving the enlarged claw] {{Webarchive|url=https://web.archive.org/web/20110722072320/http://zoo.zool.kyoto-u.ac.jp/ethol/mov/04/0402/momo040225ul01.mov |date=2011-07-22 }} - University of Kyoto
* [http://www.fiddlercrab.info/ Info on systematics, phylogeny and morphology of fiddlers] - Fiddlercrab.info
* [http://www.mysabah.com/fiddler-crab/ The colorful fiddler crabs in the mangrove forest of Borneo] - mysabah.com

{{Taxonbar|from=Q1329937}} <!-- Ocypodinae and Ucinae -->

[[Category:Ocypodoidea]]
[[Category:Asymmetry]]
[[Category:Arthropod common names]]