''Dyspanopeus sayi'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of mud

crab Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek language, Greek), which typically have a very short projecting tail-like abdomen#Arthropoda, abdomen, usually hidden entirely under the Thorax (arthropo ...

that is native to the

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

coast of North America. It has also become established outside its native range, living in

Swansea Docks Swansea Docks is the collective name for several docks in Swansea, Wales, which are immediately south-east of Swansea city centre. In the mid-19th century, the port was exporting 60% of the world's copper from factories situated in the Tawe Val ...

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 east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

since the 1970s, the

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

since 2007 and the

Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea 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 bound ...

since 2010. It can reach 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 has black tips to its unequal claws. It feeds on

bivalves Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consis ...

and

barnacle Barnacles are arthropods of the subclass (taxonomy), subclass Cirripedia in the subphylum Crustacean, Crustacea. They are related to crabs and lobsters, with similar Nauplius (larva), nauplius larvae. Barnacles are exclusively marine invertebra ...

s, and is in turn eaten by

predators Predation is a biological interaction in which 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 ...

including the Atlantic blue crab, ''

Callinectes sapidus ''Callinectes sapidus'' (from the Ancient Greek language, Ancient Greek ,"beautiful" + , "swimmer", and Latin , "savory"), the blue crab, Atlantic blue crab, or, regionally, the Maryland blue crab, is a species of crab native to the waters of t ...

''. 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 () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...

; 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 is related to both puberty and adulthood. ''Puberty'' is the biological process of sexual maturation, while ''adulthood'', the condition of being socially recognized as ...

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-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 ...

(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. Variations Olivine Olivine is the typical color of the mineral olivine. The first re ...

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 island, coral cay archipelago 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 a ...

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

intertidal zone The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...

down to depths of . It tolerates a wide range of

temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

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 to ...

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

, South

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

(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 The Venetian Lagoon (; ) is an enclosed bay of the Adriatic Sea, in northern Italy, in which the city of Venice is situated. Its name in the Italian and Venetian languages, ' (cognate of Latin ' ), has provided the English name for an enclosed, ...

(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 , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...

. It was discovered in the

in 2010, living in

Constanța Constanța (, , ) is a city in the Dobruja Historical regions of Romania, historical region of Romania. A port city, it is the capital of Constanța County and the country's Cities in Romania, fourth largest city and principal port on the Black ...

harbour (

Romania Romania is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern and Southeast Europe. It borders Ukraine to the north and east, Hungary to the west, Serbia to the southwest, Bulgaria to the south, Moldova to ...

), and in the

Ebro The Ebro (Spanish and Basque ; , , ) is a river of the north and northeast of the Iberian Peninsula, in Spain. It rises in Cantabria and flows , almost entirely in an east-southeast direction. It flows into the Mediterranean Sea, forming a de ...

delta of the

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

(western Mediterranean Sea) in 2012.

Ecology

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

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

molluscs Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

. In its native environment, it hides among colonies of

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

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

''. It is an important predator of the quahog, '' Mercenaria mercenaria'', 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. S ...

, and of the barnacle '' Balanus improvisus'' in

Delaware Bay Delaware Bay is the estuary outlet of the Delaware River on the northeast seaboard of the United States, lying between the states of Delaware and New Jersey. It is approximately in area, the bay's freshwater mixes for many miles with the saltw ...

. In the

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

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

Chamelea gallina ''Chamelea gallina'' is a species of small saltwater clam, a marine Bivalvia, bivalve in the Family (biology), family Veneridae, the venus clams. Taxonomy Carl Linnaeus originally described ''Venus gallina'' from the Mediterranean Sea in 1758. ...

'', and the introduced Asian date mussel, '' Musculista senhousia''.

Life cycle

The life cycle of ''D. sayi'' begins with

copulation Sexual intercourse (also coitus or copulation) is a sexual activity typically involving the insertion of the erect male penis inside the female vagina and followed by thrusting motions for sexual pleasure, reproduction, or both.Sexual inte ...

, which normally takes place shortly after the female has moulted, while her

exoskeleton An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. human skeleton, that ...

is still soft.

Spawning Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...

occurs within hours or days of copulation, and the eggs are brooded on the female's

pleopod 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 (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 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 relative change in the other quantity proportional to the ...

;

extrapolation In mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. ...

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 s ...

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

synonym A synonym is a word, morpheme, or phrase that means precisely 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 a ...

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 Verri ...

described seven new species in the genus '' Panopeus'', 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 con ...

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 an American scientist. He was interested particularly in marine biology. Stimpson became an important early contributor to the work of the Smithsonian Institution and later, director o ...

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

independently synonymised "''P. sayi''" with "''P. texana''", which remained until Mary J. Rathbun 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 Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

, 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 millipe ...

References

{{Portal bar, Crustaceans Xanthoidea Crabs of the Atlantic Ocean Crustaceans described in 1869 Taxa named by Sidney Irving Smith