Dekapoda

Dekapoda. The Decapoda or decapods (literally “tenfooted”) are an order of crustaceans within the class Malacostraca including many familiar groups such as crabs lobsters crayfish shrimp and prawns Most decapods are scavengers The order is estimated to contain nearly 15000 species in around 2700 genera with around 3300 fossil species Class Order Decapoda 1802Kingdom Phylum.

Decapoda The Decapoda (Latreille) represent a very significant order that is assigned to the class Malacostraca and encompasses an immense diversity of marine freshwater and semiterrestrial crustaceans with some 10000 species having been described.

Decapod definition of decapod by The Free Dictionary

dec•a•pod (ˈdɛk əˌpɒd) n 1 any crustacean of the order Decapoda having five pairs of limbs including the crabs lobsters crayfish prawns and shrimps 2 any cephalopod having ten arms as a cuttlefish or squid adj 3 belonging or pertaining to the decapods 4 having ten feet or legs.

decapod crustacean Britannica

Evolution and SystematicsPhysical CharacteristicsDistributionHabitatBehaviorFeeding Ecology and DietReproductive BiologyConservation StatusSignificance to HumansSpecies AccountsThe order Decapoda falls within the class Malacostraca a group of crustaceans that comprises twice as many species as all other crustacean classes combined Malacostracans are distinguished by bodies divided into 19 segments (five head eight thoracic and six abdominal segments) and the location of their genital openings Many of the divisions within the Malacostraca are based in part on the number of thoracic appendages that have been integrated into the head region to function as mouthparts these appendages are termed maxillipeds In the decapods the first three thoracic appendages are maxillipeds leaving five pairs of legs or ten feet for walking The order name Decapoda literally means “tenfooted” The two suborders within the Decapoda are based in part on differences in the gill structure The gills of the Dendrobranchiata consist of bundles of branching filaments while those of the Pleocyemata are unbranched—either as filaments (trichobranchs) or more commonly as unbran In addition to having five pairs of legs decapods are distinguished by the carapace that covers the dorsal portion of the head and thorax forming a single functional unit termed the cephalothorax The sides of the carapace extend downward to envelop the gills forming lateral branchial chambers Although the vast majority of decapods are aquatic and breathe with gills some terrestrial forms have developed blood vessels in the inner surface of the branchial chambers so that they function as lungs Decapods have two pairs of antennae as do all crustaceans The first pair typically bears special chemosensory structures that govern the sense of smell while the second pair is often elongate and tactile The foremost legs often have claws that perform several functions related to feeding mating and defense The structure and function of the abdomen varies among the different decapod taxa Lobsters and shrimplike forms have large muscular abdomens that terminate in a flattened tail Decapod crustaceans occur worldwide The marine species are most diverse in the IndoPacific region but relatively uncommon in extreme deepsea and polar waters Freshwater crabs and crayfish are most diverse in Southeast Asia and North America respectively crayfish occur naturally on all continents except Africa and Antarctica Terrestrial decapods are largely limited to tropical and subtropical regions and occur on all continents except Europe and Antarctica Approximately 90% of all species of decapods are marine fewer than 1% are terrestrial Although there are some species of midwater shrimps that seldom if ever encounter the bottom of the ocean the vast majority of decapods are associated with benthic habitats Marine decapods live in all types of habitats from intertidal mud flats to deepsea hot vents Such highly structured habitats as rock or coral reefs seagrass beds and mangrove forests support the greatest numbers of species but even featureless sand and mud bottoms support many types that are adept at burying themselves Most decapods emerge to feed only at night when fewer predatory fishes are active Structures to hide in are also important for freshwater decapods they are most abundant in vegetated areas Many freshwater decapods construct burrows that allow them to remain in contact with ground water when their pond dries up Terrestrial decapods are also dependent on water while some crabs can occur as much as 9 mi (15 km) from the ocean and up to 3280 ft (1000 m) above sea level they all have pla Decapods exhibit many complex and even spectacular behaviors The Caribbean spiny lobster Panulirus argus sometimes migrates toward deeper water in long lines or queues of as many as 65 individuals The reason for these migrations is not entirely clear but seems to be associated with avoidance of winter storms Juvenile red king crabs (Paralithodes camtschaticus) often gather together into mounds that may contain thousands of individuals possibly to deter predators Many decapods use visual and even auditory signals to communicate with one another Sounds are usually produced with some type of stridulating surface and this means of communication is most common in terrestrial and semiterrestrial species Stridulation refers to sounds produced by rubbing body parts together Communication using pheromones appears to be common in aquatic species especially in conjunction with mating Pheromones are released in the urine via the antennal gland when crayfish fight they literally blo Decapods employ a wide variety of feeding techniques ranging from filter feeding grazing and deposit feeding to predation Some are specialists that use just one of these methods while others are generalists that make use of several different techniques depending on the circumstances One of the most common misconceptions about crabs and other decapods is that they are primarily scavengers since many are harvested from baited pots Most large marine crustaceans are actually very efficient predators and only scavenge when the opportunity arises The decapod body plan allows for a great degree of specialization in feeding structures this specialization is especially apparent in the structure of the claws Fast slender claws can be used to snatch elusive prey while massive strong claws armed with molars can exert tremendous force on mollusks and other hardshelled prey Much of the elaborate ornamentation and other features seen in marine snails and other mollusks is a side ef With the exception of one species of crayfish decapods reproduce sexually and in almost all cases the sexes are separate A number of caridean shrimps are protandric hermaphrodites which means that they mature as males first and later change into females a few species retain male structures and become functional hermaphrodites Some species of snapping shrimps live in colonies with only one reproducing “queen” much like social insects In species where there is intense competition for mates the claws of males are often proportionately much larger than those of females An extreme example of this disproportion is seen in the fiddler crabs (Ucaspp) in which one of the claws of the male is useless for feeding and functions only to attract females and duel with other males Courtship and mating can take anywhere from seconds to weeks depending on the species Copulation in penaeid and caridean shrimps is often an instant affair while mating in crabs is often a long process inv In the year 2002 there were 176 species of decapods listed by the IUCN Of these 159 were freshwater crayfish all but two of the remaining species were shrimps or brachyuran crabs that also live in freshwater Freshwater species often have very limited distributions making them especially susceptible to habitat destruction or degradation Only one marine species was listed but virtually nothing is known about the populations of most marine decapods especially those that are not commercially exploited Three species of crayfish and three species of shrimp were listed as threatened in the United States The order Decapoda encompasses nearly all of the crustaceans that are used for human consumption and supports many large and valuable fisheries In addition penaeid shrimps and crayfish are extensively cultured for food in many parts of the world A number of human fatalities have been caused by the consumption of poisonous crabs Several reefdwelling species of IndoPacific crabs appear to acquire toxins from their food since toxicity varies with the crab&#39s diet and location it can be very difficult to determine whether one of these crabs is safe to eat In other areas decapods are often host to such schistosome parasites as lung flukes which can infect humans who eat raw or poorly cooked freshwater crabs or crayfish In some rice farming areas land crabs are considered serious pests both because they eat the plants and because they dig burrows that drain water from the fields The burrowing activities of thalassinid shrimps have had serious effects on oyster culture when Red swamp crayfish Procambarus clarkii Sevenspine bay shrimp Crangon septemspinosa Chinese mitten crab Eriocheir sinensis.

Decapoda (Crabs, Shrimps, and Lobsters) Encyclopedia.com

Decapoda [plural noun] an order of Crustaceans (division Eucarida) including the most highly organized crustaceans (as shrimps lobsters crabs) having five pairs of thoracic appendages one or more of which are modified into pincers a pair of movable stalked eyes mouthparts consisting of a pair of mandibles two pairs of maxillae and three.