Red-claw mangrove crab
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Subphylum:
Crustacea
Class:
Malacostraca
Order:
Decapoda
Infraorder:
Brachyura
Family:
Sesarmidae
Genus:
Parasesarma
Species:
P. guttatum
Binomial name
Perisesarma guttatum
(Milne-Edwards, 1869)
Synonyms
  • Chiromanthes guttatum (A. Milne Edwards, 1869)
  • Sesarma guttatum A. Milne-Edwards, 1869[1]

The Red-claw mangrove crab[2] (Perisesarma guttatum) is a crab species in the genus Parasesarma and the family Sesarmidae.[3] It is distributed in coastal brackish water habitats of the western Indian Ocean.[4][5]

Description

Along with the other species within the genus Perisesarma, the red-claw mangrove crab has a relatively square-shaped carapace and a “tooth” protruding off the sides of it.[6] The hand (claw) of the crab consists of a palm and dactylus. At the end of the dactylus are oval or circular shaped bumps called tubercles. The part leading up to the claws, the chelar carpus, also has pectinate crests on males within the genus.[6] A pectinate crest is a ridge-like projection on the crab; these ridges line the chelar carpus side-by-side.[7] Different species of Perisesarma vary in the amount of their tubercles in addition to the number of pectinate crests.[6]

Perisesarma guttatum have 20 pectinate crests and 11 to 13 oval-shaped tubercles on top of their claws.[6][8] Their claws are reddish in color with bright orange internal palms. The carapace is about 3 cm in length and between 1.5 and 2.2 cm in width on average in adults.[9] At maturity, males display larger claws than females, showing sexual dimorphism.[9][3] Sexual dimorphism is when there is a difference (often in visible attributes) between sexes within one species of organism.

P. Samawati, a sympatric species, was confused for P. guttatum until more recently, though their morphologies are distinctly different.[10] Unlike P. guttatum, P. Samawati only has 7 to 9 tubercles on the upper surface of their claws.[8][10] The size of their bodies differs as well.[10]

Distribution

P. guttatum is a mangrove inhabitant mostly located by Avicennia marina. The species inhabit these mangroves in east African coasts and Madagascar.[11] Despite increases in pollution from sewage in these areas, the crabs tolerate and are even capable of using the excess nutrients, making them less helpful in measuring mangrove health.[9][12]

Ecology

The species use burrows and natural crevices made by Neosarmatium smithi to hide from predators and also for survival. Perisesarma guttatum is mainly herbivorous, eating dead plant material and other organic matter foraged from the estuarine or forest floor during low tides.[9][12][11] Their diets therefore contribute to leaf turnover and the general removal of matter from the substratum.[13][10]

Reproduction and Life History

Females begin to reach sexual maturity around 2 years old; adults then mate throughout the year, but a study suggests that breeding correlates with lunar phases.[3] Females tend to release their larvae before spring tides, which occur during new and full moons.[3] However, females cannot breed for two consecutive spring tides, which suggests this pattern is seen due to two breeding groups within one population.[3]

During the early stages of life, planktonic larvae move offshore and are distributed with the help of ocean currents.[13] They later return as megalopa larvae – the step in their development that comes after 5 planktonic life stages – and settle in the nearshore environments around where they were once born.[13]

References

  1. ↑ "Perisesarma guttatum (A. Milne-Edwards, 1869)". World Register of Marine Species (WoRMS). Retrieved 1 November 2016.
  2. ↑ "Observations in the Species: Perisesarma guttatum". © The Open University. Retrieved 1 November 2016.
  3. 1 2 3 4 5 Flores AA, Saraiva J, Paula J (January 2002). "Sexual maturity, reproductive cycles, and juvenile recruitment of Perisesarma guttatum (Brachyura, Sesarmidae) at Ponta Rasa mangrove swamp, Inhaca Island, Mozambique". Journal of Crustacean Biology. 22 (1): 143–156. doi:10.1163/20021975-99990217.
  4. ↑ "Sesarma guttatum Milne-Edwards, 1869". sea life base. Retrieved 1 November 2016.
  5. ↑ "Perisesarma guttatum (Milne-Edwards, 1869)". sea life base. Retrieved 1 November 2016.
  6. 1 2 3 4 Shahdadi A, Schubart CD (January 2015). "Evaluating the consistency and taxonomic importance of cheliped and other morphological characters that potentially allow identification of species of the genus Perisesarma De Man, 1895 (Brachyura, Sesarmidae)". Crustaceana. 88 (10–11): 1079–1095. doi:10.1163/15685403-00003473. ISSN 1568-5403.
  7. ↑ Bowling B (2012). "Crustacean Glossary". Texas Parks and Wildlife Department. Retrieved 24 April 2022.
  8. 1 2 "Perisesarma guttatum (A. Milne Edwards, 1869)". A field guide to Kenyan mangroves. Retrieved 1 November 2016.
  9. 1 2 3 4 Amaral V, Penha-Lopes G, Paula J (July 2009). "RNA/DNA ratio of crabs as an indicator of mangrove habitat quality". Aquatic Conservation: Marine and Freshwater Ecosystems. 19 (S1): S56–S62. doi:10.1002/aqc.1039. S2CID 84150126.
  10. 1 2 3 4 Gillikin DP, Schubart CD (July 2004). "Ecology and systematics of mangrove crabs of the genus Perisesarma (Crustacea: Brachyura: Sesarmidae) from East Africa". Zoological Journal of the Linnean Society. 141 (3): 435–445. doi:10.1111/j.1096-3642.2004.00125.x.
  11. 1 2 Fratini S, Ragionieri L, Cannicci S (December 2017). "Correction: Demographic History and Reproductive Output Correlates with Intraspecific Genetic Variation in Seven Species of Indo-Pacific Mangrove Crabs". PLOS ONE. 12 (12): e0189550. Bibcode:2017PLoSO..1289550F. doi:10.1371/journal.pone.0189550. PMC 5724817. PMID 29228041.
  12. 1 2 Cannicci S, Bartolini F, Dahdouh-Guebas F, Fratini S, Litulo C, Macia A, et al. (September 2009). "Effects of urban wastewater on crab and mollusc assemblages in equatorial and subtropical mangroves of East Africa" (PDF). Estuarine, Coastal and Shelf Science. Marine Science in the Western Indian Ocean Responds to Population Pressures and Climate Change. 84 (3): 305–317. Bibcode:2009ECSS...84..305C. doi:10.1016/j.ecss.2009.04.021. ISSN 0272-7714.
  13. 1 2 3 Silva IC, Mesquita N, Paula J (January 2010). "Genetic and morphological differentiation of the mangrove crab Perisesarma guttatum (Brachyura: Sesarmidae) along an East African latitudinal gradient". Biological Journal of the Linnean Society. 99 (1): 28–46. doi:10.1111/j.1095-8312.2009.01338.x.
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