Callinectes sapidus (from the Greek
calli- = "beautiful",
nectes = "swimmer", and Latin
sapidus = "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 Ocean and the Gulf of Mexico, and introduced internationally.
C. sapidus is of significant culinary and economic importance in the United States, particularly in Louisiana, the Chesapeake Bay, and New Jersey. It is the Maryland state crustacean and is the state's largest commercial fishery
Callinectes sapidus is a decapod crab of the swimming crab family Portunidae. The genus Callinectes is distinguished from other portunid crabs by the lack of an internal spine on the carpus (the middle segment of the claw), as well as by the T-shape of the male abdomen.Blue crabs may grow to a carapace width of 23 cm (9.1 in). C. sapidus individuals exhibit sexual dimorphism. Males and females are easily distinguished by the shape of the abdomen (known as the "apron") and by color differences in the chelipeds, or claws. The abdomen is long and slender in males, but wide and rounded in mature females. A popular mnemonic is that the male's apron is shaped like the Washington Monument, while the mature female's resembles the dome of the United States Capitol. Claw color differences are more subtle than apron shape. The immovable, fixed finger of the claws in males is blue with red tips, while females have orange coloration with purple tips. A female's abdomen changes as it matures: an immature female has a triangular-shaped abdomen, whereas a mature female's is rounded
Other species of Callinectes may be easily confused with C. sapidus because of overlapping ranges and similar morphology. One species is the lesser blue crab (C. similis). It is found further offshore than the common blue crab, and has a smoother granulated carapace. Males of the lesser blue crab also have mottled white coloration on the swimming legs, and females have areas of violet coloration on the internal surfaces of the claws. C. sapidus can be distinguished from another related species found within its range, C. ornatus, by number of frontal teeth on the carapace. C. sapidus has four, while C. ornatus has six.
The crab's blue hue stems from a number of pigments in the shell, including alpha-crustacyanin, which interacts with a red pigment,astaxanthin, to form a greenish-blue coloration. When the crab is cooked, the alpha-crustacyanin breaks down, leaving only the astaxanthin, which turns the crab to a red-orange or a hot pink color
Callinectes sapidus is native to the western edge of the Atlantic Ocean from Cape Cod to Argentina and around the entire coast of the Gulf of Mexico. It has recently been reported north of Cape Cod in the Gulf of Maine, potentially representing a range expansion due to climate change. It has been introduced (via ballast water) to Japanese and European waters, and has been observed in the Baltic, North, Mediterranean and Black Seas. The first record from European waters was made in 1901 at Rochefort, France. In some parts of its introduced range, C. sapidus has become the subject of crab fishery, including in Greece, where the local population may be decreasing as a result of overfishing. From Wikipedia, the free encyclopedia
Photos Liopetri, 7/8/2014, by George Konstantinou
Calcinus tubularis is a species of hermit crab. It is found in the Mediterranean Sea and around islands in the Atlantic Ocean, where it lives below the intertidal zone. Its carapace, eyestalks and claws are marked with numerous red spots. C. tubularis and its sister species, C. verrilli, are the only hermit crabs known to show sexual dimorphism in shell choice, with males using normal marine gastropod shells, while females use shells of gastropods in the family Vermetidae, which are attached to rocks or other hard substrates.
Atergatis roseus has a wide, smooth, oval carapace with convex almost entire, with no indication of regions and with bluntly crested anterolateral margins. The pereiopods are laterally compressed with distal crests on the upper and lower margins. The carapace is reddish brown and the legs have black tips, younger specimens are paler, more reddish orange, with a white margins to the carapace. They grow to 6 cm, measuring the carapace length from the head to the posterior.
Callinectes sapidus (from the Greek calli- = "beautiful", nectes = "swimmer", and Latin sapidus = "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 Ocean and the Gulf of Mexico, and introduced internationally.
Pachygrapsus marmoratus is a species of crab, sometimes called the marbled rock crab or marbled crab, which lives in the Black Sea, the Mediterranean Sea and parts of the Atlantic Ocean. It is dark violet brown, with yellow marbling, and with a body up to 36 millimetres (1.4 in) long. It is an omnivore, feeding on algae and various animals including mussels and limpets.
Eriphia verrucosa, sometimes called the warty crab or yellow crab, is a species of crab found in the Black Sea, Mediterranean Sea and eastern Atlantic Ocean from Brittany to Mauritania and the Azores. Individual crabs have been caught as far north as Cornwall.Formerly a frequent species in the Black Sea, it has decreased in numbers since the 1980s and is now listed in the Ukrainian Red Data Book of endangered species.
E. verrucosa lives among stones and seaweeds in shallow water along rocky coastlines up to a depth of 15 metres (49 ft). It is reported to feed on bivalves, gastropods and hermit crabs, or on molluscs and polychaetes. In the Black Sea, E. verrucosa is the only native species capable of breaking into the shells of the invasive snail Rapana venosa, although it is unlikely that it will present an effective biological control of the invader. The species is threatened by eutrophication and pollution.
Percnon gibbesi 
Adults have a carapace 30 millimetres (1.2 in) wide, and legs with yellow rings at the joints. Each of the five pairs of walking legs has a row of spines along the leading edge. Females carrying eggs have been caught off West Africa between February and April and August; the larvae which hatch from them are planktonic and long-lived, which may contribute to the species' invasiveness
