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== Reproduction and life stages ==
== Reproduction and life stages ==

[[File:FMIB 46404 Larval stages of the common shore crab (Carcinus maenas).jpeg|thumb|Basic crab life cycle]]
crab reproduction occurs through a process known as [[Spawn (biology)|spawning]] where eggs are released onto the abdomen of the famle crab via the oviduct.<ref name=":3">{{Cite book |last=WEIS |first=JUDITH S. |url=https://www.jstor.org/stable/10.7591/j.cttn34xc |title=Walking Sideways: The Remarkable World of crabs |date=2012 |publisher=Cornell University Press |isbn=978-0-8014-5050-1 |edition=1 |jstor=10.7591/j.cttn34xc }}</ref> The spawning season for ''Armases cinereum'' is typically between March and July.<ref>{{Cite journal |last1=Hasek |first1=B. E. |last2=Felder |first2=D. L. |date=2005-03-01 |title=Biochemical composition of ovary, embryo, and hepatopancreas in the grapsoid crabs Armases cinereum and Sesarma nr. reticulatum (Crustacea, Decapoda) |url=https://www.sciencedirect.com/science/article/pii/S1096495904003768 |journal=Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology |language=en |volume=140 |issue=3 |pages=455–463 |doi=10.1016/j.cbpc.2004.11.010 |pmid=15694594 |issn=1096-4959}}</ref> The species in the genus ''Armases'' are known as ovigerous, meaning they carry their eggs while they undergo embryonic development.<ref name=":3" /><ref>{{Cite journal |last1=Cuesta |first1=José A. |last2=Anger |first2=Klaus |date=2001 |title=Larval Morphology of the Sesarmid crab Armases angustipes Dana, 1852 (Decapoda, Brachyura, Grapsoidea) |url=https://www.jstor.org/stable/1549582 |journal=Journal of Crustacean Biology |volume=21 |issue=3 |pages=821–838 |doi=10.1163/20021975-99990175 |jstor=1549582 |issn=0278-0372}}</ref> ''Armases cinereum'' produce between 2,000 and 12,000 eggs in a brood.<ref name=":4">{{Cite journal |last1=Figueiredo |first1=Joana |last2=Penha-Lopes |first2=Gil |last3=Anto |first3=Justin |last4=Narciso |first4=Luís |last5=Lin |first5=Junda |date=2008-04-01 |title=Fecundity, brood loss and egg development through embryogenesis of Armases cinereum (Decapoda: Grapsidae) |url=https://doi.org/10.1007/s00227-008-0922-2 |journal=Marine Biology |language=en |volume=154 |issue=2 |pages=287–294 |doi=10.1007/s00227-008-0922-2 |s2cid=55307816 |issn=1432-1793}}</ref> This number is dependent on [[fecundity]] which is proportional to the size of the female producing the eggs.<ref name=":3" /> Additionally fecundity represents the energy investment an individual must make to produce a brood of eggs.<ref name=":4" /> Eggs are energetically expensive to produce and being ovigerous in nature adds to the energy expendature. When these eggs hatch larva called [[Crustacean larva|zoea]] emerge.<ref name=":3" /> Zoea are planktonic crab larvae with their trait characteristic being a large spine positioned dorsally.<ref name=":3" /> crab zoea will grow and [[Moulting|molt]] several times before they move into their next life stage called the megalopa stage.<ref name=":3" /> In this stage the eyes become positioned on eyestalks, a carpace is formed, and the abdomen becomes positioned outward from the carpace posteriorly.<ref name=":3" /> The next time the crab molts it will become a juvenile version of its adult form and its larval life stages will be complete.<ref name=":3" />
Crab reproduction occurs through a process known as [[Spawn (biology)|spawning]] where eggs are released onto the abdomen of the female crab via the oviduct.<ref name=":3">{{Cite book |last=WEIS |first=JUDITH S. |url=https://www.jstor.org/stable/10.7591/j.cttn34xc |title=Walking Sideways: The Remarkable World of crabs |date=2012 |publisher=Cornell University Press |isbn=978-0-8014-5050-1 |edition=1 |jstor=10.7591/j.cttn34xc }}</ref> The spawning season for ''Armases cinereum'' is typically between March and July.<ref>{{Cite journal |last1=Hasek |first1=B. E. |last2=Felder |first2=D. L. |date=2005-03-01 |title=Biochemical composition of ovary, embryo, and hepatopancreas in the grapsoid crabs Armases cinereum and Sesarma nr. reticulatum (Crustacea, Decapoda) |url=https://www.sciencedirect.com/science/article/pii/S1096495904003768 |journal=Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology |language=en |volume=140 |issue=3 |pages=455–463 |doi=10.1016/j.cbpc.2004.11.010 |pmid=15694594 |issn=1096-4959}}</ref> The species in the genus ''Armases'' are known as ovigerous, meaning they carry their eggs while they undergo embryonic development.<ref name=":3" /><ref>{{Cite journal |last1=Cuesta |first1=José A. |last2=Anger |first2=Klaus |date=2001 |title=Larval Morphology of the Sesarmid crab Armases angustipes Dana, 1852 (Decapoda, Brachyura, Grapsoidea) |url=https://www.jstor.org/stable/1549582 |journal=Journal of Crustacean Biology |volume=21 |issue=3 |pages=821–838 |doi=10.1163/20021975-99990175 |jstor=1549582 |issn=0278-0372}}</ref> ''Armases cinereum'' produce between 2,000 and 12,000 eggs in a brood.<ref name=":4">{{Cite journal |last1=Figueiredo |first1=Joana |last2=Penha-Lopes |first2=Gil |last3=Anto |first3=Justin |last4=Narciso |first4=Luís |last5=Lin |first5=Junda |date=2008-04-01 |title=Fecundity, brood loss and egg development through embryogenesis of Armases cinereum (Decapoda: Grapsidae) |url=https://doi.org/10.1007/s00227-008-0922-2 |journal=Marine Biology |language=en |volume=154 |issue=2 |pages=287–294 |doi=10.1007/s00227-008-0922-2 |s2cid=55307816 |issn=1432-1793}}</ref> This number is dependent on [[fecundity]] which is proportional to the size of the female producing the eggs.<ref name=":3" /> Additionally fecundity represents the energy investment an individual must make to produce a brood of eggs.<ref name=":4" /> Eggs are energetically expensive to produce and being ovigerous in nature adds to the energy expendature. When these eggs hatch larva called [[Crustacean larva|zoea]] emerge.<ref name=":3" /> Zoea are planktonic crab larvae with their trait characteristic being a large spine positioned dorsally.<ref name=":3" /> crab zoea will grow and [[Moulting|molt]] several times before they move into their next life stage called the megalopa stage.<ref name=":3" /> In this stage the eyes become positioned on eyestalks, a carpace is formed, and the abdomen becomes positioned outward from the carpace posteriorly.<ref name=":3" /> The next time the crab molts it will become a juvenile version of its adult form and its larval life stages will be complete.<ref name=":3" />


== References ==
== References ==

Revision as of 02:13, 12 April 2022

Armases cinereum
File:Wharf crab on rock close up.jpg
wharf crab
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Brachyura
Family: Sesarmidae
Genus: Armases
Species:
A. cinereum
Binomial name
Armases cinereum

Armases cinereum, also known as the squareback marsh crab or wharf crab, Is a member of the genus Armases and is a species of crab in the family Sesarmidae.[1] The wharf crab is a small crab and is dark brown to muddy in color, which allows it to blend in well with its usual surroundings. It is found on the Atlantic southeastern coast, down into the Gulf of Mexico.[2] It is an omnivore and is prevalent in marshy coastal environments along the Southwestern Atlantic .[3]


File:Wharf crab on rock.jpg
wharf crab blending into a rocky environment.

Description

The genus Armases is defined by a primarily equatorial smooth carpace, which can be either slightly wider than long or vice versa.[2] A distinct row of hair is present on the lower margin and second walking legs do not have any pubescence.[2]Armases can be distinguished from members of other genera such as Sesarma or Sarmatium by the way its carapace has laterally parallel margins on each side of its body.[2] This gives Armases cinereum its characteristic square shape and is the namesake for squareback marsh crab.

Armases cinereum, like most decapod crabs is vertically compressed with the majority of its body being composed of the carpace; the eyes are located at the top of eye stalks, the abdomen and thorax are positioned under the carpace, and there are four legs on each side of the carpace with one claw per side positioned anterior of the legs.[4]

Sexual dimorphism

Sexual dimorphism is evident in the species, as males are typically slightly larger and have a more prominent palm.[2] Its size ranges from 10.0 to 18.0 mm in length for mature males and 11.0 to 17.2 mm for mature females.[2] Males have a subtriangular outline on thair abdomen with a telson that is equal in width and length, while females have a subcircular outline on their abdomen with the telson being larger in width than length.[2]

Mangrove Habitat
Salt Marsh Habitat

Habitat and Distribution

The wharf crab has a wide distribution in temperate to tropical coastal environments. Ther species has an abundantly high density in the coastal areas where it is found.[5] Specimens can be found from the Chesapeake Bay area down and around coastal Florida, and west along the coast all the way to Veracruz, Mexico.[6][2] The species is usually found in intertidal zones and can be found up to 50 m inland; they can thrive in a variety of habitats as well.[2] These habitats commonly include Spartina (marsh grass) marshes and Rhizophora (mangrove) swamps.[2] Within these habitats they prefer to live among and under rocks and debris brought in with the tides. Due to the high population density in coastal environments wharf crabs can be used as indicators of habitat conditions.[5]

Diet & Ecology

While the wharf crab is often deemed a detritivore, it is highly omnivorous and will supplement a detritus diet with microscopic insects and invertebrates.[7] In mangrove habitats wharf crabs are a key component as omnivores in the food chain, they serve as carnivores, herbivores, and detritivores.[5] Some examples of what the wharf crab would eat in a Mangrove habitat include, insects, partially decomposed Avicennia (Black Mangrove), and leaves from Mangroves or other maritime vegetation.[5] When feeding on plant matter wharf crabs will prioritze softer plants over plants with a tougher exterior.[8] When both plant and animal food sources are readily available the wharf crab will choose the animal prey.[5] The diet of Armases cinereum coincides directly with the environment in which it is found and what the prominent food availability is in that environment. Consequently, this diverse diet also allows the species to live at relatively high population densities across a large margin of coastal ecosystems.[5]

Taxonomy

Armases is a genus which is a part of the family Sesarmidae and the subfamily Sesarminae of Grapsidae.[2] There are around 10 described genera within the subfamily Sesarminae.[2] Armases cinereum is one of 11 described species in the genus Armases.[1][2] The species cinereum was originally described by Louis Bosc in 1802, and was classified under the genus Sesarma.[9] However, in 1992, the species was reclassified under the genus Armases by Lawrence Able.[2]

Reproduction and life stages

Crab reproduction occurs through a process known as spawning where eggs are released onto the abdomen of the female crab via the oviduct.[10] The spawning season for Armases cinereum is typically between March and July.[11] The species in the genus Armases are known as ovigerous, meaning they carry their eggs while they undergo embryonic development.[10][12] Armases cinereum produce between 2,000 and 12,000 eggs in a brood.[13] This number is dependent on fecundity which is proportional to the size of the female producing the eggs.[10] Additionally fecundity represents the energy investment an individual must make to produce a brood of eggs.[13] Eggs are energetically expensive to produce and being ovigerous in nature adds to the energy expendature. When these eggs hatch larva called zoea emerge.[10] Zoea are planktonic crab larvae with their trait characteristic being a large spine positioned dorsally.[10] crab zoea will grow and molt several times before they move into their next life stage called the megalopa stage.[10] In this stage the eyes become positioned on eyestalks, a carpace is formed, and the abdomen becomes positioned outward from the carpace posteriorly.[10] The next time the crab molts it will become a juvenile version of its adult form and its larval life stages will be complete.[10]

References

  1. ^ a b "ITIS - Report: Armases cinereum". www.itis.gov. Retrieved 2022-04-09.
  2. ^ a b c d e f g h i j k l m n Abele, Lawrence G. (1992). "A review of the Grapsid crab genus Sesarma (Crustacea: Decapoda: Grapsidae) in America, with the description of a new genus". Smithsonian Contributions to Zoology (527): 1–60. doi:10.5479/si.00810282.527. ISSN 0081-0282.
  3. ^ Buck, Tracy L.; Breed, Greg A.; Pennings, Steven C.; Chase, Margo E.; Zimmer, Martin; Carefoot, Thomas H. (2003-07-29). "Diet choice in an omnivorous salt-marsh crab: different food types, body size, and habitat complexity". Journal of Experimental Marine Biology and Ecology. 292 (1): 103–116. doi:10.1016/S0022-0981(03)00146-1. ISSN 0022-0981.
  4. ^ Abbas, Eman M.; Abdelsalam, Khaled M.; Mohammed-Geba, Khaled; Ahmed, Hamdy O.; Kato, Mikio (2016-09-01). "Genetic and morphological identification of some crabs from the Gulf of Suez, Northern Red Sea, Egypt". The Egyptian Journal of Aquatic Research. 42 (3): 319–329. doi:10.1016/j.ejar.2016.08.003. ISSN 1687-4285.
  5. ^ a b c d e f Kiskaddon, Erin; Chernicky, Kiley; Bell, Susan (2019-02-15). "Resource use by and trophic variability of Armases cinereum (Crustacea, Brachyura) across human-impacted mangrove transition zones". PLOS ONE. 14 (2): e0212448. Bibcode:2019PLoSO..1412448K. doi:10.1371/journal.pone.0212448. ISSN 1932-6203. PMC 6377144. PMID 30768634.
  6. ^ Williams, Austin B. (1984). "Shrimps, Lobsters, and crabs of the Atlantic Coast of the Eastern United States, Maine to Florida". Estuaries. 8 (1): 77. doi:10.2307/1352125. ISSN 0160-8347. JSTOR 1352125. S2CID 83630574.
  7. ^ Zimmer, Martin; Pennings, Steven C.; Buck, Tracy L.; Carefoot, Thomas H. (2004-10-01). "Salt marsh litter and detritivores: A closer look at redundancy". Estuaries. 27 (5): 753–769. doi:10.1007/BF02912038. ISSN 0160-8347. S2CID 10318266.
  8. ^ Pennings, Steven C.; Carefoot, Thomas H.; Siska, Erin L.; Chase, Margo E.; Page, Teresa A. (1998). "Feeding Preferences of a Generalist Salt-Marsh crab: Relative Importance of Multiple Plant Traits". Ecology. 79 (6): 1968–1979. doi:10.1890/0012-9658(1998)079[1968:FPOAGS]2.0.CO;2. ISSN 0012-9658.
  9. ^ Bosc, Louis Augustin Guillaume (1828). Histoire naturelle des crustacés, contenant leur description et leurs moeurs: avec figures dessinées d'après nature (in French). Roret, Libraire, Rue Hautefeuille.
  10. ^ a b c d e f g h WEIS, JUDITH S. (2012). Walking Sideways: The Remarkable World of crabs (1 ed.). Cornell University Press. ISBN 978-0-8014-5050-1. JSTOR 10.7591/j.cttn34xc.
  11. ^ Hasek, B. E.; Felder, D. L. (2005-03-01). "Biochemical composition of ovary, embryo, and hepatopancreas in the grapsoid crabs Armases cinereum and Sesarma nr. reticulatum (Crustacea, Decapoda)". Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. 140 (3): 455–463. doi:10.1016/j.cbpc.2004.11.010. ISSN 1096-4959. PMID 15694594.
  12. ^ Cuesta, José A.; Anger, Klaus (2001). "Larval Morphology of the Sesarmid crab Armases angustipes Dana, 1852 (Decapoda, Brachyura, Grapsoidea)". Journal of Crustacean Biology. 21 (3): 821–838. doi:10.1163/20021975-99990175. ISSN 0278-0372. JSTOR 1549582.
  13. ^ a b Figueiredo, Joana; Penha-Lopes, Gil; Anto, Justin; Narciso, Luís; Lin, Junda (2008-04-01). "Fecundity, brood loss and egg development through embryogenesis of Armases cinereum (Decapoda: Grapsidae)". Marine Biology. 154 (2): 287–294. doi:10.1007/s00227-008-0922-2. ISSN 1432-1793. S2CID 55307816.