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Decapoda
The Decapoda or decapods (literally "ten-footed") 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 15,000 species in around 2,700 genera, with around 3,300 fossil species. Nearly half of these species are crabs, with the shrimp (about 3,000 species) and Anomura including hermit crabs, porcelain crabs, squat lobsters (about 2500 species) making up the bulk of the remainder. The earliest fossil decapod is the Devonian '' Palaeopalaemon''. Anatomy Decapods can have as many as 38 appendages, arranged in one pair per body segment. As the name Decapoda (from the Greek , ', "ten", and , '' -pod'', "foot") implies, ten of these appendages are considered legs. They are the pereiopods, found on the last five thoracic segments. In many decapods, one pair of these "legs" has enlarged pincers, called chelae, with the l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 world's oceans, in freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers. They first appeared during the Jurassic Period. Description Crabs are generally covered with a thick exoskeleton, composed primarily of highly mineralized chitin, and armed with a pair of chelae (claws). Crabs vary in size from the pea crab, a few millimeters wide, to the Japanese spider crab, with a leg span up to . Several other groups of crustaceans with similar appearances – such as king crabs and porcelain crabs – are not true crabs, but have evolved features similar to true crabs through a process known as carcinisation. Environment Crabs are found in all of the world's oceans, as well as i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods emerged deep in the Crustacean group, with the completed group referred to as Pancrustacea. Some crustaceans ( Remipedia, Cephalocarida, Branchiopoda) are more closely related to insects and the other hexapods than they are to certain other crustaceans. The 67,000 described species range in size from '' Stygotantulus stocki'' at , to the Japanese spider crab with a leg span of up to and a mass of . Like other arthropods, crustaceans have an exoskeleton, which they moult to grow. They are distinguished from other groups of arthropods, such as insects, myriapods and chelicerates, by the possession of biramous (two-parted) l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dendrobranchiata
Dendrobranchiata is a suborder of decapods, commonly known as prawns. There are 540 extant species in seven families, and a fossil record extending back to the Devonian. They differ from related animals, such as Caridea and Stenopodidea, by the branching form of the gills and by the fact that they do not brood their eggs, but release them directly into the water. They may reach a length of over and a mass of , and are widely fished and farmed for human consumption. Shrimp and prawns While Dendrobranchiata and Caridea belong to different suborders of Decapoda, they are very similar in appearance, and in many contexts such as commercial farming and fisheries, they are both often referred to as "shrimp" and "prawn" interchangeably. In the United Kingdom, the word "prawn" is more common on menus than "shrimp", while the opposite is the case in North America. The term "prawn" is also loosely used to describe any large shrimp, especially those that come 15 (or fewer) to the pound (su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caridea
The Caridea, commonly known as caridean shrimp or true shrimp, are an infraorder of shrimp within the order Decapoda. This infraorder contains all species of true shrimp. They are found widely around the world in both fresh and salt water. Many other animals with similar names – such as the mud shrimp of Axiidea and the boxer shrimp of Stenopodidea – are not true shrimp, but many have evolved features similar to true shrimp. Biology Carideans are found in every kind of aquatic habitat, with the majority of species being marine. Around a quarter of the described species are found in fresh water, however, including almost all the members of the species-rich family Atyidae and the Palaemonidae subfamily Palaemoninae. They include several commercially important species, such as '' Macrobrachium rosenbergii'', and are found on every continent except Antarctica. The marine species are found at depths to , and from the tropics to the polar regions. In addition to the great vari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anomura
Anomura (sometimes Anomala) is a group of decapod crustaceans, including hermit crabs and others. Although the names of many anomurans include the word ''crab'', all true crabs are in the sister group to the Anomura, the Brachyura (the two groups together form the clade Meiura). Description The name Anomura derives from an old classification in which reptant decapods were divided into Macrura (long-tailed), Brachyura (short-tailed) and Anomura (differently-tailed). The alternative name Anomala reflects the unusual variety of forms in this group; whereas all crabs share some obvious similarities, the various groups of anomurans are quite dissimilar. The group has been moulded by several instances of carcinisation – the development of a crab-like body form. Thus, the king crabs (Lithodidae), porcelain crabs (Porcellanidae) and hairy stone crab (Lomisidae) are all separate instances of carcinisation. As decapods (meaning ''ten-legged''), anomurans have ten pereiopods, but the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astacidea
Astacidea is an infraorder of decapod crustaceans including lobsters (though not "lobsters" such as the spiny lobster etc.), crayfish, and their close relatives. Description The Astacidea are distinguished from most other decapods by the presence of chelae (claws) on each of the first three pairs of pereiopods (walking legs), the first of which is much larger than the remaining two pairs. The last two pairs of pereiopods are simple (without claws), except in ''Thaumastocheles'', where the fifth pereiopod may have "a minute pincer". Distribution Members of the infraorder Astacidea are found throughout the world – both in the oceans and in fresh water – except for mainland Africa and parts of Asia. Classification Astacidea belongs to the group Reptantia, which consists of the walking/crawling decapods (lobsters and crabs). Astacidea is the sister clade to the infraorder Polychelida, a small group of crustaceans restricted to deep waters. The cladogram below shows Astacidea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleocyemata
Pleocyemata is a suborder of decapod crustaceans, erected by Martin Burkenroad in 1963. Burkenroad's classification replaced the earlier sub-orders of Natantia and Reptantia with the monophyletic groups Dendrobranchiata (prawns) and Pleocyemata. Pleocyemata contains all the members of the Reptantia (including crabs, lobsters, crayfish, and others), as well as the Stenopodidea (which contains the so-called "boxer shrimp" or "barber-pole shrimp"), and Caridea, which contains the true shrimp. Anatomy All members of the Pleocyemata are united by a number of features, the most important of which is that the fertilised eggs are incubated by the female, and remain stuck to the pleopods (swimming legs) until the zoea larvae are ready to hatch. It is this characteristic that gives the group its name. Pleocyemata also possess a lamellar gill structure as opposed to the branches found in the Dendrobranchiata. Systematics The cladogram below shows Pleocyemata as the sister clade to Den ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crayfish
Crayfish are freshwater crustaceans belonging to the clade Astacidea, which also contains lobsters. In some locations, they are also known as crawfish, craydids, crawdaddies, crawdads, freshwater lobsters, mountain lobsters, rock lobsters, mudbugs, baybugs or yabbies. Taxonomically, they are members of the superfamilies Astacoidea and Parastacoidea. They breathe through feather-like gills. Some species are found in brooks and streams, where fresh water is running, while others thrive in swamps, ditches, and paddy fields. Most crayfish cannot tolerate polluted water, although some species, such as '' Procambarus clarkii'', are hardier. Crayfish feed on animals and plants, either living or decomposing, and detritus. The term "crayfish" is applied to saltwater species in some countries. Terminology The name "crayfish" comes from the Old French word ' ( Modern French '). The word has been modified to "crayfish" by association with "fish" (folk etymology). The largely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coconut Crab
The coconut crab (''Birgus latro'') is a species of terrestrial hermit crab, also known as the robber crab or palm thief. It is the largest terrestrial arthropod in the world, with a weight of up to . It can grow to up to in width from the tip of one leg to the tip of another. It is found on islands across the Indian Ocean, and parts of the Pacific Ocean as far east as the Gambier Islands, Pitcairn Islands and Caroline Island, similar to the distribution of the coconut palm; it has been extirpated from most areas with a significant human population, including mainland Australia and Madagascar. Coconut crabs also live off the coast of Africa near Zanzibar. The coconut crab is the only species of the genus ''Birgus'', and is related to the other terrestrial hermit crabs of the genus ''Coenobita''. It shows a number of adaptations to life on land. Juvenile coconut crabs use empty gastropod shells for protection like other hermit crabs, but the adults develop a tough exoskele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squat Lobster
Squat lobsters are dorsoventrally flattened crustaceans with long tails held curled beneath the cephalothorax. They are found in the two superfamilies Galatheoidea and Chirostyloidea, which form part of the decapod infraorder Anomura, alongside groups including the hermit crabs and mole crabs. They are distributed worldwide in the oceans, and occur from near the surface to deep sea hydrothermal vents, with one species occupying caves above sea level. More than 900 species have been described, in around 60 genera. Some species form dense aggregations, either on the sea floor or in the water column, and a small number are commercially fished. Description The two main groups of squat lobsters share most features of their morphology. They resemble true lobsters in some ways, but are somewhat flattened dorsoventrally, and are typically smaller. Squat lobsters vary in carapace length (measured from the eye socket to the rear edge), from in the case of '' Munidopsis aries'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malacostraca
Malacostraca (from New Latin; ) is the largest of the six classes of crustaceans, containing about 40,000 living species, divided among 16 orders. Its members, the malacostracans, display a great diversity of body forms and include crabs, lobsters, crayfish, shrimp, krill, prawns, woodlice, amphipods, mantis shrimp, tongue-eating lice and many other less familiar animals. They are abundant in all marine environments and have colonised freshwater and terrestrial habitats. They are segmented animals, united by a common body plan comprising 20 body segments (rarely 21), and divided into a head, thorax, and abdomen. Etymology The name Malacostraca was coined by a French zoologist Pierre André Latreille in 1802. He was curator of the arthropod collection at the National Museum of Natural History in Paris. The name comes from the Greek roots (', meaning "soft") and (', meaning "shell"). The name is misleading, since the shell is soft only immediately after moulting, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porcelain Crab
Porcelain crabs are decapod crustaceans in the widespread family Porcellanidae, which superficially resemble true crabs. They have flattened bodies as an adaptation for living in rock crevices. They are delicate, readily losing limbs when attacked, and use their large claws for maintaining territories. They first appeared in the Tithonian age of the Late Jurassic epoch, 145–152 million years ago. Description Porcelain crabs are small, usually with body widths less than . They share the general body plan of a squat lobster, but their bodies are more compact and flattened, an adaptation for living and hiding under rocks. Porcelain crabs are quite fragile animals, and often shed their limbs to escape predators, hence their name. The lost appendage can grow back over several moults. Porcelain crabs have large chelae (claws), which are used for territorial struggles, but not for catching food. The fifth pair of pereiopods is reduced and used for cleaning. Evolution Porcelain cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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