''Minuca pugnax'', commonly known as the Atlantic marsh fiddler crab, is a species of

fiddler crab The fiddler crab or calling crab can be one of the hundred species of semiterrestrial marine crabs in the family Ocypodidae. These crabs are well known for their extreme sexual dimorphism, where the male crabs have a major claw significantly l ...

that lives on north-western shores of the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

Distribution

''Minuca pugnax'' is the most common species of fiddler crab on the

east coast of the United States The East Coast of the United States, also known as the Eastern Seaboard, the Atlantic Coast, and the Atlantic Seaboard, is the region encompassing the coast, coastline where the Eastern United States meets the Atlantic Ocean; it has always pla ...

. Its natural

range Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...

extends from

Cape Cod Cape Cod is a peninsula extending into the Atlantic Ocean from the southeastern corner of Massachusetts, in the northeastern United States. Its historic, maritime character and ample beaches attract heavy tourism during the summer months. The ...

to northern

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

. In 2014, its northern limit was extended to Hampton, New Hampshire, as a result of a range expansion possibly due to

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

. Prior to the 2000s, studies suggested that its habitat range was limited to low-marsh habitats such as creeks, bay fronts, and mosquito ditches that are regularly flooded by the tide; the number of crabs decreased substantially in high-marsh habitats. Reports also indicated that ''Minuca pugnax'' would burrow during high tide and not reemerge until the tide had receded. The habitat was therefore restricted to areas where burrows were available to occupy and could be constructed. However reports in the 2010s began noting higher than expected numbers of ''Minuca pugnax'' in high-marsh areas along the

Long Island Sound Long Island Sound is a sound (geography), marine sound and tidal estuary of the Atlantic Ocean. It lies predominantly between the U.S. state of Connecticut to the north and Long Island in New York (state), New York to the south. From west to east, ...

and in Rhode Island. ''Minuca pugnax'' has a mutualistic relationship with ''

Spartina alterniflora ''Sporobolus alterniflorus'', or synonymously known as ''Spartina alterniflora'', the smooth cordgrass, saltmarsh cordgrass, or salt-water cordgrass, is a perennial deciduous grass which is found in intertidal wetlands, especially estuarine salt ...

'', a perennial deciduous grass found in intertidal wetlands; the plants provide structural support necessary for the crabs' burrows and the burrowing itself increases production of the grass. However, in bare areas of the marshes caused by human disruption, the burrowing can damage the ''S. alterniflora'' seedlings by disturbing the soil, which also increases sediment in the water column and reduce the amount of organic matter in the soil. All of these can increase the negative impacts of

sea level rise The sea level has been rising from the end of the last ice age, which was around 20,000 years ago. Between 1901 and 2018, the average sea level rose by , with an increase of per year since the 1970s. This was faster than the sea level had e ...

on wetland ecosystems.

Description

There is noticeable

sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

in ''Minuca pugnax''. Although both males and females are olive-brown in color, males have a

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

width of , and a patch of

royal blue Royal blue is a deep and vivid shade of blue. It is said to have been created by a consortium of mills in Rode, Wiltshire (in Somerset as of 1937), which won a competition to make a robe for Queen Charlotte, consort of King George III. I ...

on the carapace, while females lack the blue patch and are only across the carapace. In both sexes, the

pereiopod The anatomy of a decapod consists of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment – often called a somite – may possess one pair of appendages, although in various groups these m ...

s (walking legs) have dark bands, and the

eyestalk In anatomy, an eyestalk (sometimes spelled eye stalk and also known as an ommatophore) is a protrusion that extends an eye away from the body, giving the eye a better field of view. It is a common feature in nature and frequently appears in fict ...

s are narrow. The most conspicuous difference is the form of the

cheliped A chela ()also called a claw, nipper, or pinceris a pincer-shaped organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through Neo-Latin '. The plural form is chelae. Legs bearing a chela are called chelipeds ...

s (claw-bearing legs); in females, they are similar, while in males, one is greatly enlarged and colored yellow.

Life cycle

The males use circular movements of their large cheliped to attract a mate. Mating occurs up to every two weeks, typically 4–5 days after the

spring tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...

s, over a period lasting from June to September. It takes place in a burrow, after which the female will brood her eggs for 12–15 days before releasing the hatchling

larvae A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect developmental biology, development such as insects, some arachnids, amphibians, or cnidarians typical ...

on the high spring tides. The larvae pass through five

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

zoea Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The ...

and one megalopa stages before settling to the sea floor to molt into the adult form. This process takes around 28 days. After one year, the crab reaches

sexual maturity Sexual maturity is the capability of an organism to reproduce. In humans, it is related to both puberty and adulthood. ''Puberty'' is the biological process of sexual maturation, while ''adulthood'', the condition of being socially recognized ...

, and adult life span is typically 12–18 months.

Taxonomic history

''Minuca pugnax'' was first described by

Sidney Irving Smith Sidney Irving Smith (February 18, 1843, in Norway, Maine – May 6, 1926, in New Haven, Connecticut) was an American zoologist. Private life Sidney Smith was the son of Elliot Smith and Lavinia Barton. His brother in law was Addison Emery Verri ...

in 1870, as "''Gelasimus pugnax''". Its

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

s include "marsh fiddler crab", "mud fiddler crab", "Atlantic mud fiddler crab" and "Atlantic marsh fiddler crab". ''Minuca pugnax'' was formerly a member of the genus '' Uca'', but in 2016 it was placed in the genus '' Minuca'', a former subgenus of ''Uca''.

References

{{Taxonbar, from=Q837229 Ocypodoidea Crabs of the Atlantic Ocean Crustaceans described in 1870 Taxa named by Sidney Irving Smith