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.
Malacostraca is the second largest of the six classes of pancrustaceans just behind hexapods, 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, and divided into a head, thorax, and abdomen.
The Decapoda or decapods are an order of crustaceans within the class Malacostraca, and includes crabs, lobsters, crayfish, shrimp, and prawns. Most decapods are scavengers. The order is estimated to contain nearly 15,000 extant 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 fossils of the group date to the Devonian.
Mysida is an order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a brood pouch or "marsupium" in females. The fact that the larvae are reared in this pouch and are not free-swimming characterises the order. The mysid's head bears a pair of stalked eyes and two pairs of antennae. The thorax consists of eight segments each bearing branching limbs, the whole concealed beneath a protective carapace and the abdomen has six segments and usually further small limbs.
Isopoda is an order of crustaceans. Members of this group are called Isopods and include both terrestrial and aquatic species such as woodlice. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, and five pairs of branching appendages on the abdomen that are used in respiration. Females brood their young in a pouch under their thorax.
The decapod is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment may possess one pair of appendages, although in various groups these may be reduced or missing. They are, from head to tail:
The Cephalocarida are a class in the subphylum Crustacea comprising only 12 species. Both the nauplii and the adults are benthic. They were discovered in 1955 by Howard L. Sanders, and are commonly referred to as horseshoe shrimp. They have been grouped together with the Remipedia in the Xenocarida. Although a second family, Lightiellidae, is sometimes used, all cephalocaridans are generally considered to belong in just one family: Hutchinsoniellidae. Fossil records of cephalocaridans has been found in 462 million year old deposits.
Leptostraca is an order of small, marine crustaceans. Its members, including the well-studied Nebalia, occur throughout the world's oceans and are usually considered to be filter-feeders. It is the only extant order in the subclass Phyllocarida. They are believed to represent the most primitive members of their class, the Malacostraca, and first appear in the fossil record during the Cambrian period.
Eumalacostraca is a subclass of crustaceans, containing almost all living malacostracans, or about 40,000 described species. The remaining subclasses are the Phyllocarida and possibly the Hoplocarida. Eumalacostracans have 19 segments. This arrangement is known as the "caridoid facies", a term coined by William Thomas Calman in 1909. The thoracic limbs are jointed and used for swimming or walking. The common ancestor is thought to have had a carapace, and most living species possess one, but it has been lost in some subgroups.
Cumacea is an order of small marine crustaceans of the superorder Peracarida, occasionally called hooded shrimp or comma shrimp. Their unique appearance and uniform body plan makes them easy to distinguish from other crustaceans. They live in soft-bottoms such as mud and sand, mostly in the marine environment. There are more than 1,500 species of cumaceans formally described. The species diversity of Cumacea increases with depth.
Triops longicaudatus is a freshwater crustacean of the order Notostraca, resembling a miniature horseshoe crab. It is characterized by an elongated, segmented body, a flattened shield-like brownish carapace covering two thirds of the thorax, and two long filaments on the abdomen. The genus name Triops comes from Greek ὤψ or ṓps, meaning "eye" prefixed with Latin tri-, "three", in reference to its three eyes. Longicaudatus is a Latin neologism combining longus ("long") and caudatus ("tailed"), referring to its long tail structures. Triops longicaudatus is found in fresh water ponds and pools, often in places where few higher forms of life can exist.
Diastylidae is one of the eight most commonly recognised families of crustaceans of the order Cumacea. They are marine creatures especially common around the 30th parallel north.
Gynodiastylidae is one of the eight most commonly recognised families of crustaceans of the order Cumacea. They are especially prevalent in the southern hemisphere, with some types described from Japan, Thailand and the Persian Gulf. Most are found at less than 100 metres (330 ft) depth.
Leuconidae is a family of marine hooded shrimp. The family was established by Georg Ossian Sars in his 1878 study of Mediterranean cumaceans.
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.
Phylogeny of Malacostraca is the evolutionary relationships of the largest of the six classes of crustaceans, containing about 40,000 living species, divided among 16 orders. Its members display a great diversity of body forms. Although the class Malacostraca is united by a number of well-defined and documented features, which were recognised a century ago by William Thomas Calman in 1904, the phylogenetic relationship of the orders which compose this class is unclear due to the vast diversity present in their morphology. Molecular studies have attempted to infer the phylogeny of this clade, resulting in phylogenies which have a limited amount of morphological support. To resolve a well-supported eumalacostracan phylogeny and obtain a robust tree, it will be necessary to look beyond the most commonly utilized sources of data.
Periclimenes pholeter, is a species of shrimp belonging to the family Palaemonidae. The species is closest to Periclimenes indicus, P. obscurus and P. toloensis, resembling these species in the presence of an epigastric tooth on the carapace, the shape of the abdomen, the spinulation of the carapace, and the unarmed fingers of the first chelipeds. P. pholeter most resembles P. indicus by the elongatecarpus and long fingers of the second pereiopods, differing in these features from P. toloensis, which has the fingers slightly less than half as long as the palm. In P. obscurus the fingers are shorter than the palm, but the carpus is about as long as the palm. From P. indicus, this species differs: by the greater size; by the much higher rostrum and the greater number of ventral rostral teeth; by the shorter eye; by the less slender antennular peduncle; by the more deeply cleft upper antennular flagellum; by the more robust scaphocerite; by the fingers of the first pereiopods ; by the more slender pereiopods, especially the fifth, which is much longer than the ischium.
Crustaceans are a group of arthropods that are a part of the subphylum Crustacea, a large, diverse group of mainly aquatic arthropods including decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, 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. The three classes Cephalocarida, Branchiopoda and Remipedia are more closely related to the hexapods than they are to any of the other crustaceans.
Perimecturus is an extinct genus of mantis shrimp that lived during the Early Carboniferous period in what is now Scotland and the United States. The first known specimens were collected near the River Esk in Glencartholm, Scotland, and the genus was named in 1908 by Ben Peach, making it the second genus of Paleozoic mantis shrimp to be described. While many species have been classified in the genus since then, taxonomic revisions in the late 20th and 21st centuries have reassigned most of these to different genera, leaving two named species currently assigned to this genus. The type species, P. parki, was first named in 1882 as a species of Anthrapalaemon and is known from the Viséan-aged Glencartholm Volcanic Beds of Scotland. Fossils of a later species, P. rapax, have been found in the Bear Gulch Limestone of Montana and were first described by Frederick Schram.
Nodosculda is an extinct genus of mantis shrimp that lived in North America during the late Albian stage of the Early Cretaceous period, between 105 and 100 million years ago. The only species is Nodosculda fisherorum, known from several specimens uncovered in the Paw Paw Formation of Texas.
