''Dyspanopeus sayi'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of mud

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

that is native to the

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

coast of North America. It has also become established outside its native range, living in Swansea Docks since 1960, the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...

since the 1970s, the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...

since 2007 and the

Black Sea The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Roma ...

since 2010. It can reach a

carapace A carapace is a Dorsum (biology), 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 tor ...

width of , and has black tips to its unequal claws. It feeds on

bivalves Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

and

barnacle A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in eros ...

s, and is in turn eaten by

predators Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...

including the Atlantic blue crab, ''

Callinectes sapidus ''Callinectes sapidus'' (from the Ancient Greek ,"beautiful" + , "swimmer", and Latin , "savory"), the blue crab, Atlantic blue crab, or regionally as the Chesapeake blue crab, is a species of crab native to the waters of the western Atlantic O ...

''. Eggs are produced from spring to autumn, the offspring reach sexual maturity the following summer, and individuals can live for up to two years. The closest relative of ''D. sayi'' is '' D. texanus'', which lives in the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...

; the two species differ in subtle features of the genitalia and the last pair of walking legs.

Description

''Dyspanopeus sayi'' is a small crab, similar in appearance to '' Eurypanopeus depressus''. It reaches a maximum

width of , with

sexually mature Sexual maturity is the capability of an organism to reproduce. In humans it might be considered synonymous with adulthood, but here puberty is the name for the process of biological sexual maturation, while adulthood is based on cultural definitio ...

females having a carapace or more across. The carapace is roughly hexagonal, about 1.3–1.4 times as wide as long and strongly convex. It has a finely granular surface, and has a light covering of hair, especially towards the front and sides. The

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

(claws) are unequal: the right claw is stouter, and the left claw is narrower. The carapace is

olive-green Olive is a dark yellowish-green color, like that of unripe or green olives. As a color word in the English language, it appears in late Middle English. Shaded toward gray, it becomes olive drab. Variations Olivine Olivine is the typical ...

to brown, but the tips of the claws are black.

Distribution

The 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 ...

of ''D. sayi'' extends from the ' (eastern Canada) to the

Florida Keys The Florida Keys are a coral cay archipelago located off the southern coast of Florida, forming the southernmost part of the continental United States. They begin at the southeastern coast of the Florida peninsula, about south of Miami, and e ...

(south-eastern United States), where it lives from the

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...

down to depths of . It tolerates a wide range of

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

s and

salinities Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

. ''D. sayi'' has also been recorded from a number of locations in Europe. The first sighting was in Swansea Docks, South

Wales Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...

(United Kingdom) in 1960, and the scientist who reported it, E. Naylor, believed there was "no doubt" that the species had arrived through trans-Atlantic shipping. The first record from the

was made in 1993, when the species was discovered in the Venetian Lagoon (north-eastern Italy), although it is thought to have been living there since the late 1970s. In 2007, ''D. sayi'' was recorded from the

coast of the

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

. It was discovered in the

in 2010, living in

Constanța Constanța (, ; ; rup, Custantsa; bg, Кюстенджа, Kyustendzha, or bg, Констанца, Konstantsa, label=none; el, Κωνστάντζα, Kōnstántza, or el, Κωνστάντια, Kōnstántia, label=none; tr, Köstence), histo ...

harbour (

Romania Romania ( ; ro, România ) is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern, and Southeast Europe, Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, S ...

), and in the

Ebro , name_etymology = , image = Zaragoza shel.JPG , image_size = , image_caption = The Ebro River in Zaragoza , map = SpainEbroBasin.png , map_size = , map_caption = The Ebro ...

delta of the

Balearic Sea The Balearic Sea ( endotoponym: ''Mar Balear'' in Catalan and Spanish) is a body of water in the Mediterranean Sea between the Balearic Islands and the mainland of Spain. The Ebro River flows into this small sea. Islands and archipelagoes Th ...

(western Mediterranean Sea) in 2012.

Ecology

''Dyspanopeus sayi'' lives predominantly on muddy bottoms, where it is a

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

molluscs Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant taxon, extant species of molluscs are recognized. The number of fossil sp ...

. In its native environment, it hides among colonies of

polychaete Polychaeta () is a paraphyletic class (biology), class of generally marine invertebrate, marine annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that ...

s to avoid being preyed on by the Atlantic blue crab, ''

''. It is an important predator of the quahog, ''

Mercenaria mercenaria The hard clam (''Mercenaria mercenaria''), also known as the round clam, hard-shell (or hard-shelled) clam, or the quahog, is an edible marine bivalve mollusk that is native to the eastern shores of North America and Central America from Prince E ...

'', in

Narragansett Bay Narragansett Bay is a bay and estuary on the north side of Rhode Island Sound covering , of which is in Rhode Island. The bay forms New England's largest estuary, which functions as an expansive natural harbor and includes a small archipelago. Sma ...

, and of the barnacle ''

Balanus improvisus ''Amphibalanus improvisus'', the bay barnacle, European acorn barnacle, is a species of Sessilia, acorn barnacle in the Family (biology), family Balanidae. Description ''Amphibalanus improvisus'' has a smooth white or pale grey conical calcareou ...

'' in

Delaware Bay Delaware Bay is the estuary outlet of the Delaware River on the northeast seaboard of the United States. It is approximately in area, the bay's freshwater mixes for many miles with the saltwater of the Atlantic Ocean. The bay is bordered inlan ...

. In the

Adriatic Sea The Adriatic Sea () is a body of water separating the Italian Peninsula from the Balkan Peninsula. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto (where it connects to the Ionian Sea) to t ...

, it has been observed to feed on the striped venus clam, ''

Chamelea gallina ''Chamelea gallina'' is a species of small saltwater clam, a marine bivalve in the family Veneridae, the venus clams. Taxonomy Carl Linnaeus originally described ''Venus gallina'' from the Mediterranean Sea in 1758. It was not clear whether d ...

'', and the introduced Asian date mussel, ''

Musculista senhousia : ''For the Asian green mussel, see Perna viridis.'' ''Arcuatula senhousia'', commonly known as the Asian date mussel, Asian mussel or bag mussel, is a small saltwater mussel, a marine bivalve mollusk species in the family Mytilidae, the musse ...

''.

Life cycle

The

life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring *Life-cycle hypothesis, ...

of ''D. sayi'' begins with

copulation Sexual intercourse (or coitus or copulation) is a sexual activity typically involving the insertion and thrusting of the penis into the vagina for sexual pleasure or reproduction.Sexual intercourse most commonly means penile–vaginal penetrat ...

, which normally takes place shortly after the female has

moulted In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

, while her

exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...

is still soft.

Spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquati ...

occurs within hours or days of copulation, and the

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

are brooded on the female's

pleopod The decapod ( crustaceans such as a crab, lobster, shrimp or prawn) is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment may possess one pair of appendages, although in various ...

s (swimmerets) until they are ready to hatch. Females have been found carrying eggs from April to October; in a study of crabs caught at

Gloucester Point, Virginia Gloucester Point is a census-designated place (CDP) in Gloucester County, Virginia, United States. The population was 9,402 at the 2010 census. It is home to the College of William & Mary's Virginia Institute of Marine Science, a graduate school f ...

in 1978, females were observed to carry between 686 and 14,735 eggs. The number of eggs increases with carapace width according to a

power law In statistics, a power law is a Function (mathematics), functional relationship between two quantities, where a Relative change and difference, relative change in one quantity results in a proportional relative change in the other quantity, inde ...

;

extrapolation In mathematics, extrapolation is a type of estimation, beyond the original observation range, of the value of a variable on the basis of its relationship with another variable. It is similar to interpolation, which produces estimates between know ...

of the power law suggests that the largest ''D. sayi'' females are capable of carrying over 32,000 eggs each. At , the eggs can take only 9 or 10 days to develop, and this increases to 16 days at temperatures of . The young crabs hatch as zoea larvae, and pass through three further zoeal stages and one

megalopa 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 ...

before becoming juveniles. Juveniles are thought to reach maturity in the summer after they hatch. The total lifespan of an individual can be up to 2 years.

Taxonomy

The species had been noticed by the American zoologist

Thomas Say Thomas Say (June 27, 1787 – October 10, 1834) was an American entomologist, conchologist, and Herpetology, herpetologist. His studies of insects and shells, numerous contributions to scientific journals, and scientific expeditions to Florida, Ge ...

, and formed part of the species he called "''Cancer panope''" – a

junior homonym In biology, a homonym is a name for a taxon that is identical in spelling to another such name, that belongs to a different taxon. The rule in the International Code of Zoological Nomenclature is that the first such name to be published is the se ...

of "''Cancer panope''" Herbst, 1801, which is itself a junior

synonym A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

of '' Sphaerozius scaber'' (Fabricius, 1798). In 1869,

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 Verrill. ...

described seven new species in the genus ''

Panopeus Panopeus (), or Phanoteus (the name is given in a variety of forms in the ancient sources), was a Greek town of ancient Phocis, near the frontier of Boeotia, and on the road from Daulis to Chaeronea. Pausanias said that Panopeus was 20 stadia from ...

'', including "''P. sayi''", in addition to the twelve species already placed in the genus at that time.

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 contrast ...

s for the species include "Say's mud crab" and "Say mud crab". Smith noted the similarity of the species to "''Panopeus texanus''", which had been described ten years earlier by

William Stimpson William Stimpson (February 14, 1832 – May 26, 1872) was a noted American scientist. He was interested particularly in marine biology. Stimpson became an important early contributor to the work of the Smithsonian Institution and later, direc ...

, and Smith considered that the two might be the same species. In 1880,

John Sterling Kingsley John Sterling Kingsley (1854–1929) was an American professor of biology and zoology. Early life John Kingsley was born on 7 April 1854 in Cincinnatus, New York son of Lewis and Julia A. (née Kingman) Kingsley.Twentieth Century Biographical ...

and

Alphonse Milne-Edwards Alphonse Milne-Edwards (Paris, 13 October 1835 – Paris, 21 April 1900) was a French mammalogist, ornithologist, and carcinologist. He was English in origin, the son of Henri Milne-Edwards and grandson of Bryan Edwards, a Jamaican planter who se ...

independently synonymised "''P. sayi''" with "''P. texana''", which remained until

Mary J. Rathbun Mary Jane Rathbun (June 11, 1860 – April 4, 1943) was an American zoologist who specialized in crustaceans. She worked at the Smithsonian Institution from 1884 until her death. She described more than a thousand new species and subspecies and ...

moved both taxa to the genus '' Neopanope'' and re-established Smith's taxon as a subspecies of "''N. texana''". She argued that the two taxa should be considered

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

, as hybrids between them occurred, although the specimens she saw are now thought to be ''D. sayi''. In 1972, Lawrence G. Abele re-examined "''N. texanus texanus''", "''N. texanus sayi''" and '' N. packardi'', and concluded that they were all good species, and so re-elevated "''N. sayi''" to the rank of species. In 1986, Joel W. Martin and Abele placed ''N. texanus'' and ''N. sayi'' in a separate genus, '' Dyspanopeus'', reaffirming their close relationship. However, ''P. texana'' only occurs in the

, and can be distinguished from ''P. sayi'' by the form of the fifth pereiopod (last walking leg) and that of the male

gonopod Gonopods are specialized appendages of various arthropods used in reproduction or egg-laying. In males, they facilitate the transfer of sperm from male to female during mating, and thus are a type of intromittent organ. In crustaceans and millip ...

References

{{Taxonbar, from=Q3042133 Xanthoidea Crustaceans of the Atlantic Ocean Crustaceans described in 1869 Taxa named by Sidney Irving Smith