| Reptantia | |
|---|---|
 | |
| European lobster ( Homarus gammarus ) | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Crustacea |
| Class: | Malacostraca |
| Order: | Decapoda |
| Suborder: | Pleocyemata |
| (unranked): | Reptantia Boas, 1880 |
| Infraorders | |
Reptantia is a clade of decapod crustaceans named in 1880 which includes lobsters, crabs and many other well-known crustaceans.
In older classifications, Reptantia was one of the two sub-orders of Decapoda alongside Natantia, with Reptantia containing the walking forms, and Natantia containing the swimming forms (prawns, shrimp and boxer shrimp). However, in 1963 Martin Burkenroad found Natantia to be paraphyletic and invalid, and instead split Decapoda into the two sub-orders of Dendrobranchiata (prawns) and Pleocyemata. Pleocyemata contains all the members of the Reptantia (including crabs, lobsters, crayfish, and others), as well as the Stenopodidea ("boxer shrimp"), and Caridea (true shrimp). [1] Reptantia remains a valid monophyletic grouping, but is now no longer ranked as a sub-order. [2]
The name Reptantia means "those that walk", and contains those decapods whose primary mode of locomotion is to walk along a surface using the pereiopods rather than swimming through the water with the pleopods. Despite this, many reptants are able to propel themselves through the water, and many non-reptants can and will walk.
The cladogram below shows Reptantia under the sub-order Pleocyemata within the larger order Decapoda, from analysis by Wolfe et al., 2019. [2]
| Decapoda |
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Reptantia comprises the following infraorders:
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 ghost shrimps, mud shrimps, and boxer shrimps – are not true shrimps, but many have evolved features similar to true shrimps.
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 330 millimetres (13 in) and a mass of 450 grams (1.0 lb), and are widely fished and farmed for human consumption.
Natantia is an obsolete taxon of decapod crustaceans, comprising those families that move predominantly by swimming – the shrimp, prawns (Dendrobranchiata) and boxer shrimp. The remaining Decapoda were placed in the Reptantia, and consisted of crabs, lobsters and other large animals that move chiefly by walking along the bottom. The division between Natantia and Reptantia was replaced in 1963, when Martin Burkenroad erected the suborder Pleocyemata for those animals that brood their eggs on the pleopods, leaving Dendrobranchiata for the prawns. Under this system, Natantia is a paraphyletic group. Burkenroad's primary division of Decapoda into Dendrobranchiata and Pleocyemata has since been corroborated by molecular analyses.
The Decapoda or decapods 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 and Anomura including hermit crabs, porcelain crabs, squat lobsters making up the bulk of the remainder. The earliest fossil decapod is the Devonian Palaeopalaemon.
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, as well as the Stenopodidea, and Caridea, which contains the true shrimp.
The Achelata is an infra-order of the decapod crustaceans, holding the spiny lobsters, slipper lobsters and their fossil relatives.
Anomura 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 Stenopodidea or boxer shrimps are a small group of decapod crustaceans. Often confused with Caridea shrimp or Dendrobranchiata prawns, they are neither, belonging to their own group.
Astacidea is an infraorder of decapod crustaceans including lobsters, crayfish, and their close relatives.
Thalassinidea is a former infraorder of decapod crustaceans that live in burrows in muddy bottoms of the world's oceans. In Australian English, the littoral thalassinidean Trypaea australiensis is referred to as the yabby, frequently used as bait for estuarine fishing; elsewhere, however, they are poorly known, and as such have few vernacular names, "mud lobster" and "ghost shrimp" counting among them. The burrows made by thalassinideans are frequently preserved, and the fossil record of thalassinideans reaches back to the late Jurassic.
Eucarida is a superorder of the Malacostraca, a class of the crustacean subphylum, comprising the decapods, krill, Amphionides and Angustidontida. They are characterised by having the carapace fused to all thoracic segments, and by the possession of stalked eyes.
Penaeidae is a family of marine crustaceans in the suborder Dendrobranchiata, which are often referred to as penaeid shrimp or penaeid prawns. The Penaeidae contain many species of economic importance, such as the tiger prawn, whiteleg shrimp, Atlantic white shrimp, and Indian prawn. Many prawns are the subject of commercial fishery, and farming, both in marine settings, and in freshwater farms. Lateral line–like sense organs on the antennae have been reported in some species of Penaeidae. At 210 metres per second (760 km/h), the myelinated giant interneurons of pelagic penaeid shrimp have the world record for impulse conduction speed in any animal.
Axiidea is an infraorder of decapod crustaceans. They are colloquially known as mud shrimp, ghost shrimp, or burrowing shrimp; however, these decapods are only distantly related to true shrimp. Axiidea and Gebiidea are divergent infraoders of the former infraorder Thalassinidea. These infraorders have converged ecologically and morphologically as burrowing forms. Based on molecular evidence as of 2009, it is now widely believed that these two infraorders represent two distinct lineages separate from one another. Since this is a recent change, much of the literature and research surrounding these infraorders still refers to the Axiidea and Gebiidea in combination as "thalassinidean" for the sake of clarity and reference. This division based on molecular evidence is consistent with the groupings proposed by Robert Gurney in 1938 based on larval developmental stages.
Polychelida is an infraorder of decapod crustaceans. Fossil representatives are known dating from as far back as the Upper Triassic. A total of 38 extant species, all in the family Polychelidae, and 55 fossil species have been described.
Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The larvae of crustaceans often bear little resemblance to the adult, and there are still cases where it is not known what larvae will grow into what adults. This is especially true of crustaceans which live as benthic adults, more-so than where the larvae are planktonic, and thereby easily caught.
Martin David Burkenroad was an American marine biologist. He specialized in decapod crustaceans and fisheries science.
Shrimp are decapod crustaceans with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata. More narrow definitions may be restricted to Caridea, to smaller species of either group or to only the marine species. Under a broader definition, shrimp may be synonymous with prawn, covering stalk-eyed swimming crustaceans with long, narrow muscular tails (abdomens), long whiskers (antennae), and slender legs. Any small crustacean which resembles a shrimp tends to be called one. They swim forward by paddling with swimmerets on the underside of their abdomens, although their escape response is typically repeated flicks with the tail driving them backwards very quickly. Crabs and lobsters have strong walking legs, whereas shrimp have thin, fragile legs which they use primarily for perching.
Prawn is a common name for small aquatic crustaceans with an exoskeleton and ten legs, some of which can be eaten.
Crustaceans form a large, diverse arthropod taxon which includes such animals as crabs, lobsters, crayfish, shrimp, krill, prawns, woodlice, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata; because of recent molecular studies it is now well accepted that the crustacean group is paraphyletic, and comprises all animals in the clade Pancrustacea other than hexapods. Some crustaceans are more closely related to insects and the other hexapods than they are to certain other crustaceans.
Faxonella creaseri is a species of crayfish which belongs to the larger group of so-called decapoda. It is one of the four species in the family Faxonella.
Subgroups of Order Decapoda | |||||||||||||||||||||||
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| Dendrobranchiata |   | ||||||||||||||||||||||
| Pleocyemata |
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