Editing Fiddler crab (section)

==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}}
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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>