Fiddler crab

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Fiddler crab
Temporal range: Early Miocene-recent [1]
Fiddler crab.jpg
Red-jointed fiddler crab (Minuca minax)
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Brachyura
Superfamily: Ocypodoidea
Family: Ocypodidae
Groups included

The fiddler crab or calling crab may be any of more than one hundred species of semiterrestrial marine crabs in the family Ocypodidae, [2] well known for their sexually dimorphic claws; the males' major claw is much larger than the minor claw, while the females' claws are both the same size. [3] 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 slightly over two inches (5 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.

Contents

Like all crabs, fiddler crabs 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 large fiddle claw is lost, males will develop one on the same side after their next molt. [4] Newly molted crabs are very vulnerable because of their soft shells. They are reclusive and hide until the new shell hardens.

In a 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. [5]

Ecology

Found in mangroves, in salt marshes, and on sandy or muddy beaches of West Africa, the Western Atlantic, the Eastern Pacific, Indo-Pacific and Algarve region of Portugal, fiddler crabs are easily recognized by their distinctively asymmetric claws.

Male lemon-yellow clawed fiddler crab (Austruca perplexa), waving his big claw in display Uca perplexa male waving.gif
Male lemon-yellow clawed fiddler crab ( Austruca perplexa ), waving his big claw in display

Fiddler crabs communicate by a sequence of waves and gestures; [6] males have an oversized claw or chela; used in clashes of ritualised combat of courtship over a female and signal their intentions between conspecifics. The movement of the smaller claw from ground to mouth during feeding explains the crabs' common name; it looks as if the animal were playing the larger claw like a fiddle.

The crab's smaller claw picks up a chunk of sediment from the ground and brings it to the mouth, where its contents are sifted through (making the crab a detritivore). After anything edible is salvaged, be it algae, microbes, fungus, or other decaying detritus, the sediment is replaced in the form of a little ball. The presence of these sediment balls near the entrance to a burrow is a good indication of its occupation. Some experts believe that the feeding habits of fiddler crabs play a vital role in the preservation of wetland environments; by sifting through the sands, they aerate the substrate and prevent anaerobic conditions. [7]

Life cycle

General anatomy of a fiddler crab Fiddler crab anatomy-en.svg
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 the major claw to perform a waving display as a form of female courtship. [8] Females choose their mate based on claw size and also quality of the waving display. [9] In many fiddler crab species, the female occupies the burrow of their mate while she lays her clutch of eggs. Research shows that the male major claw size is also correlated with burrow width; the width of the burrow influences incubation temperature. [10] Therefore, the female will choose a male mate whose claw size indicates the best burrow environment for her clutch of eggs. The waving display is also thought to indicate to females the overall healthiness of the male; a more vigorous display is more difficult to do and thus requires the male to be in prime health condition, which suggests that the male will help produce viable offspring. [11]

Fiddler Crabs Fighting in Belle Hall, Mount Pleasant, South Carolina on March 24, 2023 Fiddler Crabs Fighting in Belle Hall, Mount Pleasant, South Carolina on March 24, 2023.jpg
Fiddler Crabs Fighting in Belle Hall, Mount Pleasant, South Carolina on March 24, 2023

Male versus male competition also occurs as fighting with the major claws. [12] 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 planktonic for a further two weeks.

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. [13] [14] This is an example of dishonest 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. [15]

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. [16] [2] [17]

Captivity

Fiddler crabs are occasionally kept as pets. [20] 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. [20] Fiddler crabs have been known to attack small fish in captivity, as opposed to their natural feeding habits. [21]

See also

Related Research Articles

<span class="mw-page-title-main">Ocypodidae</span> Family of crabs

The Ocypodidae are a family of semiterrestrial crabs that includes the ghost crabs and fiddler crabs. They are found on tropical and temperate shorelines around the world.

<i>Leptuca pugilator</i> Species of crab

Leptuca pugilator, the sand fiddler crab, Atlantic sand fiddler crab, or Calico fiddler, is a species of fiddler crab that is found from Massachusetts to the Gulf of Mexico. It lives in burrows in coastal and estuarine mud-flats, and can be extremely abundant. It can be differentiated from the morphologically similar Minuca pugnax and Minuca minax by the smoothness of the inside of its claws. One claw is larger than the other, and can be much larger than the crab's body, at up to 41 mm (1.6 in) long.

<i>Austruca mjoebergi</i> Species of crab

Austruca mjoebergi is a species of fiddler crab discovered by and named after the Swedish zoologist Eric Mjöberg (1882–1938), member of a Swedish scientific expedition to Australia in the early 1900s.

<i>Austruca perplexa</i> Species of crab

Austruca perplexa is a species of fiddler crab. It is found from the Ryukyu Islands, Japan to India, throughout the Malay Archipelago, along eastern Australian coasts from Queensland to New South Wales, and in various Pacific islands, including Fiji, Tonga and Vanuatu.

<i>Austruca annulipes</i> Species of crab

Austruca annulipes is a species of fiddler crab found along the coastline from South Africa to Somalia, Madagascar, India, China, Indonesia, Malaysia, and the Philippines.

<i>Tubuca urvillei</i> Species of crab

Tubuca urvillei is a species of fiddler crab. It is found in the Southeastern Africa from southern Somalia to the South Africa and Madagascar.

<i>Minuca longisignalis</i> Species of crustacean

Minuca longisignalis, the longwave gulf fiddler, is a species of American broad-front fiddler crab in the family Ocypodidae.

<i>Leptuca thayeri</i> Species of crustacean

Leptuca thayeri, known generally as the Atlantic mangrove fiddler crab or mangrove fiddler, is a species of true crab in the family Ocypodidae. It is distributed all across the Western Atlantic.

<i>Tubuca</i> Genus of crabs

Tubuca is a genus in Ocypodidae, a family of fiddler and ghost crabs. There are more than 20 described species in Tubuca.

<i>Austruca</i> Genus of crabs

Austruca is a genus of indo-west Pacific fiddler crabs in the family Ocypodidae. There are about 13 described species in this genus.

<i>Leptuca</i> Genus of crabs

Leptuca is a genus of fiddler crabs belonging to the family Ocypodidae.

<i>Leptuca spinicarpa</i> Species of crab

Leptuca spinicarpa, commonly known as the spiny-wristed fiddler crab or the spined fiddler crab, is a species of fiddler crab native to coastal habitats along the Gulf of Mexico from northwestern Florida to Mexico.

<i>Leptuca panacea</i> Species of crab

Leptuca panacea, commonly known as the Gulf sand fiddler crab or the Panacea sand fiddler, is a species of fiddler crab native to coastal habitats along the Gulf of Mexico from northwestern Florida to Mexico.

Leptuca leptodactyla, commonly known as the thin-fingered fiddler crab or the western Atlantic fiddler crab, is a species of fiddler crab native to the western Atlantic coast of the Americas.

Leptuca cumulanta, commonly known as the heaping fiddler crab or the mangrove fiddler crab, is a species of fiddler crab native to tropical and subtropical areas of the western Atlantic.

Leptuca beebei, commonly known as Beebe's fiddler crab, is a species of fiddler crab native to the Pacific coasts of Central and South America, from El Salvador to northern Peru.

Leptuca batuenta, commonly known as the beating fiddler crab, is a species of fiddler crab native to the tropical eastern Pacific, from El Salvador to northern Peru.

Leptuca saltitanta, commonly known as the energetic fiddler crab, is a species of fiddler crab native to the eastern Pacific coasts, from El Salvador in Central America to Colombia in South America.

<i>Tubuca polita</i> Fiddler crab, Tubuca polita

Tubuca polita, commonly known as the polished fiddler crab. or pink-clawed fiddler crab is a species of fiddler crab that is found in the northern part of Australia including the Torres Strait Islands

<i>Tubuca coarctata</i> Species of fiddler crab

Tubuca coarctata is a species of fiddler crab found in the western Pacific ocean, including Japan, Taiwan, the Philippines, Indonesia, New Guinea and Australia. The common name of these crabs is either the compressed fiddler crab, or the orange-clawed fiddler crab,. They are found on tidal mud flats adjacent mangroves and muddy tidal creek and river banks.

References

  1. ↑ "Uca Leach 1814 (fiddler crab)". PBDB.
  2. 1 2 Rosenberg, Michael S. (2019). "A fresh look at the biodiversity lexicon for fiddler crabs (Decapoda: Brachyura: Ocypodidae). Part 1: Taxonomy". Journal of Crustacean Biology. 39 (6).
  3. ↑ Levinton, J. S., Judge, M. L., and 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, v. 193, p. 147-160.
  4. ↑ Weis, Judith S (2019-04-01). "On the Other Hand: The Myth of Fiddler Crab Claw Reversal". BioScience. 69 (4): 244–246. doi:10.1093/biosci/biz011. ISSN   0006-3568.
  5. ↑ Smith, Thomas; Smith, Robert (2012). Elements of Ecology (8 ed.). San Francisco: Pearson Benjamin Cummings. p. 144. ISBN   978-0-321-73607-9.
  6. ↑ M. J. How; J. M. Hemmi; J. Zeil; R. Peters (2008). "Claw waving display changes with receiver distance in fiddler crabs, Uca perplexa" (PDF). Animal Behaviour . 75 (3): 1015–1022. doi:10.1016/j.anbehav.2007.09.004. S2CID   44197123.
  7. ↑ Mokhtari, Mohammad; Abd Ghaffar, Mazlan; Usup, Gires; Che Cob, Zaidi (2016-01-19). "Effects of Fiddler Crab Burrows on Sediment Properties in the Mangrove Mudflats of Sungai Sepang, Malaysia". Biology. 5 (1): 7. doi: 10.3390/biology5010007 . ISSN   2079-7737. PMC   4810164 . PMID   26797647.
  8. ↑ Pope, D. S., 2000, Testing function of fiddler crab claw waving by manipulating social context: Behavioral Ecology and Sociobiology, v. 47, p. 432-437.
  9. ↑ Perez, D. M., Rosenberg, M. S., and Pie, M. R., 2012, The evolution of waving displays in fiddler crabs (Uca spp., Crustacea: Ocypodidae): Biological Journal of the Linnean Society, v. 106, p. 307-315.
  10. ↑ Reaney, L. T., and Backwell, P. R. Y., 2007, Temporal constraints and female preference for burrow width in the fiddler crab, Uca mjoebergi: Behavioral Ecology and Sociobiology, v. 61, p. 1515-1521.
  11. ↑ Matsumasa, M., Murai, M., and Christy, J. H., 2013, A low-cost sexual ornament reliably signals male condition in the fiddler crab Uca beebei: Animal Behaviour, v. 85, p. 1335-1341.
  12. ↑ Callander, S., Kahn, A. T., Maricic, T., Jennions, M. D., and Backwell, P. R. Y., 2013, Weapons or mating signals? Claw shape and mate choice in a fiddler crab: Behavioral Ecology and Sociobiology, v. 67, p. 1163-1167.
  13. ↑ British Ecological Society (November 13, 2008). "Fiddler crabs reveal honesty is not always the best policy". University of New South Wales . Retrieved November 19, 2008.
  14. ↑ Simon P. Lailvaux; Leeann T. Reaney; Patricia R. Y. Backwell (November 11, 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 .[ dead link ]
  15. ↑ Swanson, B. O., George, M. N., Anderson, S. P., and Christy, J. H., 2013, Evolutionary variation in the mechanics of fiddler crab claws: Bmc Evolutionary Biology, v. 13.
  16. ↑ Shih, Hsi-Te; Ng, Peter K. L.; Davie, Peter J. F.; Schubart, Christoph D.; et al. (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.
  17. ↑ Peter K. L. Ng; Danièle Guinot; Peter J. F. Davie (2008). "Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world" (PDF). Raffles Bulletin of Zoology . 17: 1–286. Archived from the original (PDF) on 2011-06-06.
  18. ↑ Hsi-Te Shih; Tohru Naruse; Peter K. L. Ng (2010). "Uca jocelynae sp. nov., a new species of fiddler crab (Crustacea: Brachyura: Ocypodidae) from the Western Pacific" (PDF). Zootaxa . 2337: 47–62. doi:10.11646/zootaxa.2337.1.4.
  19. ↑ Shih, H. T.; Chan, Benny K. K.; Ng, Peter K. L. (29 March 2018). "Tubuca alcocki, a new pseudocryptic species of fiddler crab from the Indian Ocean, sister to the southeastern African T. urvillei (H. Milne Edwards, 1852)". ZooKeys (747): 41–62. doi: 10.3897/zookeys.747.23468 . PMC   5904522 . PMID   29674902 . Retrieved 3 April 2018.
  20. 1 2 Lianne McLeod. "How to Set Up a Tank for Fiddler Crabs". About.com. Archived from the original on September 29, 2011. Retrieved January 13, 2010.
  21. ↑ Robert (2019-02-22). "The Complete Fiddler Crab Care Guide: Tank, Food, Facts and More…". Fishkeeping World. Retrieved 2021-04-21.
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