fiddler crab

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fiddler crab,

common name for small, amphibious crabscrab,
crustacean with an enlarged cephalothorax covered by a broad, flat shell called the carapace. Extending from the cephalothorax are the various appendages: five pairs of legs, the first pair bearing claws (or pincers), are attached at the sides; two eyes on short, movable
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 belonging to the genus Uca. They are characterized by a rectangular carapace (shell) and a narrow abdomen, which is flexed under the body. They are called fiddler crabs because the males have one enormous claw, held in front of the body like a fiddle. This claw often contrasts in color with the rest of the body, and is used by the male at certain times of the year to attract females in a complicated courtship display procedure, characteristically different in each species of Uca. The claw also functions to warn off intruders and to establish territories. The female Uca has two small claws on the first appendages. Some species of fiddler crabs live on sandy beaches that are somewhat protected from extreme wave action. Others live in muddy marshes and estuaries. The Uca species living on sandy beaches, such as the common Atlantic fiddler, U. pugilator, make burrows about 1 ft (30 cm) deep, just below the high tide line. The sand is carried to the surface by specialized legs of the crab, and pushed away from the entrance. Fiddler crabs are poor swimmers and rarely enter the water during their adult lives. During the spring and summer, the fiddlers remain in their burrows only during high tide periods. The entrances of the burrows are covered with sand, and the burrows contain a bubble of air, which the crabs use for respiration. When the tide ebbs, the fiddlers emerge and scurry about, collecting food in the drift lines left by the ebbing water. Both claws of the female and the smaller claw of the male are used to scoop up sand and pass the grains to the mouthparts. Certain specialized appendages (the first and second maxillipeds) have spoon-shaped setae, used to scour organic matter from the sand grains and pass it to the mouth. The sand grains are then rejected in the form of small sand balls. After mating, the female fiddler crab carries the fertilized eggs under her flexed abdomen. Certain cyclic changes occur in Uca (as well as in some other crustaceans), such as changes in pigmentation. During the day the crabs are dark; at night they are pale. Fiddler crabs are classified in the phylum ArthropodaArthropoda
[Gr.,=jointed feet], largest and most diverse animal phylum. The arthropods include crustaceans, insects, centipedes, millipedes, spiders, scorpions, and the extinct trilobites.
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, subphylum Crustacea, order Decapoda.
References in periodicals archive ?
Reproductive aspects of a tropical population of the fiddler crab Uca annulipes (H.
2014) showed that the intraspecific morphological variation found in eight species of fiddler crabs can be related to variation in humidity, to the relationship of humidity to water conservation in the crabs' gill chambers.
Around 97 species of fiddler crabs are currently known worldwide (Beinlich & Von Hagen, 2006; Landstofer & Schubart, 2009; Shih et al.
It appears that fiddler crabs have evolved inbuilt sunglasses, in the same way as we use polarising sunglasses to reduce glare," Professor Marshall said.
With the large claw acting as a heat sink male fiddler crabs can remain on the surface longer, foraging and performing the waving display," Dr Darnell told BBC Nature.
Ecologists knew that male fiddler crabs sometimes take on an attacker who is trying to invade a neighbor's territory.
In addition, fiddler crabs normally play a crucial role in tilling the salt marsh, which helps provide oxygen to the roots of salt marsh grasses.
In Oyster Bay Harbor, a study of food habits from dozens of adult terrapins revealed that soft shell clams, hard shell clams, blue mussels, and fiddler crabs were mainstays of their diet.
The park, the state's largest barrier island, harbors an array of animal and plant communities within its complex ecological system: whitetail deer, armadillo, fiddler crabs, loggerhead turtles, resurrection ferns, and Spanish moss.
Her research interests include gender in science issues and behavioral ecology of fiddler crabs.
However, toxic effects such as ultrastructural change in testes of gobiid fish, reduction in larval production in sand fiddler crabs, chronic toxicity in hens, acute toxicity in birds, reptiles, and fish, and decreases in muscarinic receptor function in rat retina have been reported (Mullie et al.