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Pleon
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 may be reduced or missing. Cephalothorax Head #antennules #antenna (biology), antennae #mandible (arthropod)#Crustaceans, mandibles #Maxilla (arthropod), first maxillae #Maxilla (arthropod), second maxillae The head also bears the (usually stalked) compound eyes. The distal portion of a mandible or maxilla which has a sensory function is known as a palp. Thorax / pereon #first maxillipeds #second maxillipeds #third maxillipeds #first pereiopods #second pereiopods #third pereiopods #fourth pereiopods #fifth pereiopods Maxillipeds are appendages modified to function as mouthparts. Particularly in the less advanced decapods, these can be very similar to the pereiopods. Pereiopods are primarily walking arthropod leg, legs and are also used for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dendrobranchiata
Dendrobranchiata is a suborder of Decapoda, 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 shrimp fishery, fished and shrimp farm, farmed for human consumption. Shrimp and prawns While Dendrobranchiata and Caridea belong to different Order (biology), suborders of Decapoda, they are very similar in appearance, and in many contexts such as commercial farming and Fishery, fisheries, they are both often referred to as "shrimp" and "prawn" interchangeably. In the United Kingdom, Australia and some other Commonwealth of Nations, Commonwealth, the word "prawn" is used almost exclusively, while the opposite is the case in North America. The term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 underside is called the plastron. In botany, a carapace refers to the hard outer cover of a seed which protects the inner embryo. Crustaceans In crustaceans, the carapace functions as a protective cover over the cephalothorax (i.e., the fused head and thorax, as distinct from the abdomen behind). Where it projects forward beyond the eyes, this projection is called a rostrum. The carapace is calcified to varying degrees in different crustaceans. Zooplankton within the phylum Crustacea also have a carapace. These include Cladocera, ostracods, and isopods, but isopods only have a developed "cephalic shield" carapace covering the head. Arachnids In arachnids, the carapace is formed by the fusion of prosomal tergites into a single pl ... [...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 Reptantia, 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, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 (arthropod anatomy), thorax. Their exoskeleton is often Sclerotization, thickened and hard. They generally have Arthropod leg, five pairs of legs, and they have "Pincers (tool), pincers" or "claws" on the ends of the frontmost pair, scientifically termed the ''chelae''. They are present in all the world's oceans, Freshwater crab, in freshwater, and Terrestrial crab, on land, often hiding themselves in small crevices or burrowing into sediment. Crabs are omnivores, feeding on a variety of food, including a significant proportion of Algae eater, algae, as well as Detritivore, detritus and other invertebrates. Crab meat, Crabs are widely consumed by humans as food, with over 1.5 million tonnes Crab fisheries, caught annually. True crabs first appeared ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caridoid Escape Reaction
The caridoid escape reaction, also known as lobstering or tail-flipping, is an innate escape behavior in marine and freshwater eucarid crustaceans such as lobsters, krill, shrimp and crayfish. The reaction, most extensively researched in crayfish, allows crustaceans to escape predators through rapid abdominal flexions that produce powerful thrusts that make the crustacean quickly swim backwards through the water and away from danger. The type of response depends on the part of the crustacean stimulated, but this behavior is complex and is regulated both spatially and temporally through the interactions of several neurons. Discovery of the first command neuron-mediated behavior In 1946, C. A. G. Wiersma first described the tail-flip escape in the crayfish '' Procambarus clarkii'' and noted that the giant interneurons present in the tail were responsible for the reaction. The aforementioned neuronal fibres consist of a pair of lateral giant interneurons and a pair of medi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telson
The telson () is the hindmost division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment (biology), segment of the arthropod body, or an additional division that is not a true segment on account of not arising in the embryo from teloblast areas as other segments. It never carries any appendages, but a forked "tail" called the caudal furca may be present. The shape and composition of the telson differs between arthropod groups. Crustaceans In lobsters, Caridea, shrimp and other Decapoda, decapods, the telson, along with the uropods, forms the tail fan. This is used as a paddle in the caridoid escape reaction ("lobstering"), whereby an alarmed animal rapidly flexes its tail, causing it to dart backwards. Krill can reach speeds of over 60 cm per second by this means. The Induction period, trigger time to optical stimulus (physiology), stimulus is, in spite of the low temperatures, only 55 milliseconds. In th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uropod
Uropods are posterior appendages found on a wide variety of crustaceans. They typically have functions in locomotion. Definition Uropods are often defined as the appendages of the last body segment of a crustacean. An alternative definition suggested by Frederick R. Schram restricts the term to those structures arising from the segment before the anal segment (the segment which carries the anus). Under this latter definition, the appendages of the anal segment are caudal ramus, caudal rami, which are analogy (biology), analogous to uropods. Form Uropods are typically biramous – comprising an endopod and an exopod. The exopod is typically the larger, and may be divided in two by a transverse suture known as the diaeresis. The uropods may work in concert with the telson to form a "tail fan". References {{Reflist, 32em Crustacean anatomy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biramous
The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments (called podomeres) are of Latin origin, and may be confused with terms for bones: ''coxa'' (meaning hip, : ''coxae''), ''trochanter'', ''femur'' (: ''femora''), ''tibia'' (: ''tibiae''), ''tarsus'' (: ''tarsi''), ''ischium'' (: ''ischia''), ''metatarsus'', ''carpus'', ''dactylus'' (meaning finger), ''patella'' (: ''patellae''). Homologies of leg segments between groups are difficult to prove and are the source of much argument. Some authors posit up to eleven segments per leg for the most recent common ancestor of extant arthropods but modern arthropods have eight or fewer. It has been argued that the ancestral leg need not have been so complex, and that other events, such as successive loss of function of a ''Hox''-gene, could result in parallel gains of leg segments. In arthropods, each of the leg segments articulates with the next seg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonopods
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 millipedes, gonopods are modified walking or swimming legs. Gonopods may be highly decorated with elaborate structures which may play roles in sperm competition, and can be used to differentiate and identify closely related species. Gonopods generally occur in one or more pairs, as opposed to the single (un-paired) reproductive organs such as the aedeagus of insects or the penis of harvestmen. Insects In insects, gonopods are appendages of the genital segment that may be used in insemination, or that comprise the egg-laying apparatus. Crustaceans In male decapod crustaceans, gonopods are modified swimming appendages (pleopods). The anterior two pair of pleopods in males are modified for sperm transferring, with differing degree of morphologi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uropods
Uropods are posterior appendages found on a wide variety of crustaceans. They typically have functions in locomotion. Definition Uropods are often defined as the appendages of the last body segment of a crustacean. An alternative definition suggested by Frederick R. Schram restricts the term to those structures arising from the segment before the anal segment (the segment which carries the anus). Under this latter definition, the appendages of the anal segment are caudal rami, which are analogous to uropods. Form Uropods are typically biramous – comprising an endopod and an exopod. The exopod is typically the larger, and may be divided in two by a transverse suture known as the diaeresis. The uropods may work in concert with the telson The telson () is the hindmost division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment (biology), segment of the arthropod body, or an additional division that is not a true ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swimmeret
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 may be reduced or missing. Cephalothorax Head # antennules # antennae # mandibles # first maxillae # second maxillae The head also bears the (usually stalked) compound eyes. The distal portion of a mandible or maxilla which has a sensory function is known as a palp. Thorax / pereon #first maxillipeds #second maxillipeds #third maxillipeds #first pereiopods #second pereiopods #third pereiopods #fourth pereiopods #fifth pereiopods Maxillipeds are appendages modified to function as mouthparts. Particularly in the less advanced decapods, these can be very similar to the pereiopods. Pereiopods are primarily walking legs and are also used for gathering food. They are also the ten legs from which decapods take their name. Those pereiopods which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
