Malacostraca is the second largest of the six classes of pancrustaceans behind insects, 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, spiny 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, king crabs, porcelain crabs, squat lobsters making up the bulk of the remainder. The earliest fossils of the group date to the Devonian.
King crabs are decapod crustaceans of the family Lithodidae that are chiefly found in deep waters and are adapted to cold environments. They are composed of two subfamilies: Lithodinae, which tend to inhabit deep waters, are globally distributed, and comprise the majority of the family's species diversity; and Hapalogastrinae, which are endemic to the North Pacific and inhabit exclusively shallow waters. King crabs superficially resemble true crabs but are generally understood to be closest to the pagurid hermit crabs. This placement of king crabs among the hermit crabs is supported by several anatomical peculiarities which are present only in king crabs and hermit crabs, making them a prominent example of carcinisation among decapods. Several species of king crabs, especially in Alaskan and southern South American waters, are targeted by commercial fisheries and have been subject to overfishing.
Eucarida is a superorder of the Malacostraca, a class of the crustacean subphylum, comprising the decapods, krill, and Angustidontida. They are characterised by having the carapace fused to all thoracic segments, and by the possession of stalked eyes.
Anaspides is a genus of freshwater crustaceans in the family Anaspidesidae. The genus was first described in 1894 by George Malcolm Thomson. The genus was originally placed in the family, Anaspididae by Thomson, but this genus name was preoccupied by the insect genus, Anaspis Geoffroy, 1762, and therefore, in 2017, the family was renamed Anaspidesidae by Shane Ahyong and Miguel A. Alonso-Zarazaga.
Allanaspides helonomus is a species of mountain shrimp in the family Anaspididae.
Allanaspides hickmani, also known as Hickman's Pygmy Mountain Shrimp, is a species of mountain shrimp in the family Anaspididae.
Eucrenonaspides oinotheke is a species of crustacean in the family Psammaspididae, endemic to Tasmania, the only species described in the genus Eucrenonaspides. Eucrenonaspides is in the order Anaspidacea. It was described from a spring at 9 Payton Place, Devonport, Tasmania in 1980, making it "the first spring-dwelling syncarid recorded from the Australian region". It is listed as a vulnerable species on the IUCN Red List. A further undescribed species is known from south-western Tasmania.
Typhlatya is a genus of shrimp in the family Atyidae. These are small, stygobitic shrimp found in the West Mediterranean region, Caribbean region, Ascension Island and the Galápagos, although the individual species often have very small ranges. Species in this genus are found in salt, brackish and fresh waters, mostly in anchialine habitats and none in the open sea.
Anaspidacea is an order of crustaceans, comprising eleven genera in four families. Species in the family Anaspidesidae vary from being strict stygobionts to species living in lakes, streams and moorland pools, and are found only in Tasmania. Koonungidae is found in Tasmania and the south-eastern part of the Australian mainland, where they live in the burrows made by crayfish and in caves. The families Psammaspididae and Stygocarididae are both restricted to caves, but Stygocarididae has a much wider distribution than the other families, with Parastygocaris having species in New Zealand and South America as well as Australia; two other genera in the family are endemic to South America, and one, Stygocarella, is endemic to New Zealand.
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.
Anaspides tasmaniae is a species of fresh water crustacean of the family Anaspididae found in Tasmania. It is also known by the common names "mountain shrimp" or "chris' pseudo-mantis". It has been described as a "living fossil". A. tasmaniae lives in tarns and creeks over 300 metres above sea level, and is found in Lake St Clair and Clarence Lagoon.
The clade Multicrustacea constitutes the largest superclass of crustaceans, containing approximately four-fifths of all described non-hexapod crustacean species, including crabs, lobsters, crayfish, shrimp, krill, prawns, woodlice, barnacles, copepods, amphipods, mantis shrimp and others. The largest branch of multicrustacea is the class Malacostraca.
Acanthosquilla is a genus of stomatopod crustacean. The American carcinologist Raymond B. Manning named and first circumscribed the genus in 1963. As of 2018, the World Register of Marine Species recognizes the following eight species:
Anaspides clarkei is a species of freshwater crustacean in the family Anaspidesidae, and was first described in 2015 by Shane Ahyong
Anaspides jarmani is a species of freshwater crustacean in the family Anaspidesidae, and was first described in 2015 by Shane Ahyong
Anaspides swaini is a species of freshwater crustacean in the family Anaspidesidae, and was first described in 2015 by Shane Ahyong
Anaspides driesseni is a species of freshwater crustacean in the family Anaspidesidae, and was first described in 2023 by Christoph Höpel, Stefan Richter & Shane Ahyong. In 2016 Ahyong discussed three morphologically different forms of A. swaini occurring in three different drainage systems.
Koonaspides is an extinct genus of fossil crustacean in the family Anaspidesidae, from Early Cretaceous (Aptian) Koonwarra Fossil Beds in eastern Victoria, Australia. The only known species within the genus is Koonaspides indistinctus. Along with the Triassic genus Anaspidites, this is one of two known fossil members of this family.
