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Maxillopoda
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) limbs, and by thei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Facetotecta
Facetotecta is a poorly known subclass of thecostracan crustaceans. The adult forms have never been recognised, and the group is known only from its larvae, the "y- nauplius" and "y-cyprid" larvae. They are mostly found in the north Atlantic Ocean, neritic waters around Japan, and the Mediterranean Basin, where they also survive in brackish water. History The German zoologist Christian Andreas Victor Hensen first collected facetotectans from the North Sea in 1887, but assigned them to the copepod family Corycaeidae; later Hans Jacob Hansen named them "y-nauplia", assuming them to be the larvae of unidentified barnacles. More recently, it has been suggested that, since there is a potential gap in the tantulocarid life cycle, y-larvae may be the larvae of tantulocarids. However, this would be "a very tight fit", and it is more likely that the adult forms have not yet been seen. Genetic analysis using 18S ribosomal DNA reveal Facetotecta to be the sister group to the remaining T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thecostraca
Thecostraca is a class of marine invertebrates containing over 2,200 described species. Many species have planktonic larvae which become sessile or parasitic as adults. The most important subgroup are the barnacles (subclass Cirripedia), constituting a little over 2,100 known species. The subgroup Facetotecta contains a single genus, ''Hansenocaris'', known only from the tiny planktonic nauplii called "y-larvae". These larvae have no known adult form, though it is suspected that they are parasites, and their affinity is uncertain. Some researchers believe that they may be larval tantulocaridans. No larval tantulocaridans are currently known. The group Ascothoracida contains about 110 species, all parasites of coelenterates and echinoderms. Classification This article follows Chan et al. (2021) and the World Register of Marine Species in placing Thecostraca as a class of Crustacea and in the following classification of thecostracans down to the level of orders. Previously, Theco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclida
Cyclida (formerly Cycloidea, and so sometimes known as cycloids) is an extinct order of crab-like fossil arthropods that lived from the Carboniferous to the Cretaceous. Their classification is uncertain, but they are generally interpreted as crustaceans, likely belonging to the superclass Multicrustacea. Description Cycloids have a "striking" resemblance to crabs, and are thought to have inhabited a similar ecological niche, and to have been driven to extinction when crabs became widespread and diverse. The largest members are over across the carapace. Their gills are often preserved in three dimensions, and do not resemble those of other crustaceans. Cycloid taxa differ in the number of walking legs, in the form of the mouthparts and in other significant ways. Affinities There is considerable debate about the placement of cycloids within the Arthropoda. While they are generally considered to be crustaceans of some kind, doubts have been expressed about the homology of cyclo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ascothoracida
Ascothoracida is a small group of crustaceans, comprising around 100 species. They are found throughout the world, and are parasites on cnidarians and echinoderms. Ascothoracida was previously ranked as an order within the infraclass Cirripedia ( barnacles), but now both Ascothoracida and Cirripedia are considered separate subclasses. Those two subclasses, along with Facetotecta, make up the class Thecostraca. The thorax of Ascothoracida species has six pair of biramous appendages, while the abdomen has four segments and a terminal telson The telson () is the posterior-most division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment of the arthropod body, or an additional division that is not a true segment on accou ... with a caudal furca. This arrangement is similar to that seen in copepods. In addition, there is a bivalved carapace, which is expanded in females. References External links * Maxillo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tantulocarida
Tantulocarida is a highly specialised group of parasitic crustaceans that consists of about 33 species, treated as a class in superclass Multicrustacea. They are typically ectoparasites that infest copepods, isopods, tanaids, amphipods and ostracods. Description Eyes are completely absent. Body length Members of this subclass are minute – less than in length and have a dramatic reduction in body form compared to other crustaceans, with an unsegmented, sac-like thorax and a much reduced abdomen. One tantulocarid species, ''Tantulacus dieteri'', is the world's smallest arthropod, with a total body length of only . Life cycle The tantulocarid life cycle is unique among crustaceans. The tantulus larva transforms directly from a non-feeding (lecithotrophic) and free-swimming organism into a parasite without any instars. When entering the parasitic stage much of the body, such as the muscles, degenerates, even if the body itself becomes bigger. As a parasite it is permanentl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentastomida
The Pentastomida are an enigmatic group of parasitic arthropods commonly known as tongue worms due to the resemblance of the species of the genus ''Linguatula'' to a vertebrate tongue; molecular studies point to them being degenerate crustaceans. About 130 species of pentastomids are known; all are obligate parasites with correspondingly degenerate anatomy. Adult tongue worms vary from about in length, and parasitise the respiratory tracts of vertebrates. They have five anterior appendages. One is the mouth; the others are two pairs of hooks, which they use to attach to the host. This arrangement led to their scientific name, meaning "five openings", but although the appendages are similar in some species, only one is a mouth. Taxonomy Historically significant accounts of tongue worm biology and systematics include early work by Josef Aloys Frölich, Alexander von Humboldt, Karl Asmund Rudolphi, Karl Moriz Diesing and Rudolph Leuckart. Other important summaries have been publ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cirripedia
A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile (nonmobile) and most are suspension feeders, but those in infraclass Rhizocephala are highly specialized parasites on crustaceans. They have four nektonic (active swimming) larval stages. Around 1,000 barnacle species are currently known. The name is Latin, meaning "curl-footed". The study of barnacles is called cirripedology. Description Barnacles are encrusters, attaching themselves temporarily to a hard substrate or a symbiont such as a whale ( whale barnacles), a sea snake ('' Platylepas ophiophila''), or another crustacean, like a crab or a lobster (Rhizocephala). The most common among them, "acorn barnacles" ( Sessilia), are sessile where they grow their shells directly onto the substrate. Pedunculate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mystacocarida
Derocheilocarididae is a family of crustaceans that form part of the meiobenthos. It is the only family in the monotypic order Mystacocaridida, and the monotypic subclass Mystacocarida. These mystacocarids are less than long, and live interstitially in the intertidal zones of sandy beaches. Taxonomy The taxonomy of the mystacocarids is extremely conservative, since all mystacocarids look superficially alike. , the 13 described species are divided between two genus, genera, ''Derocheilocaris'' (eight species) and ''Ctenocheilocharis'' (five species). The first mystacocarids to be found were discovered on a beach in southern New England in 1939. Distribution Mystacocarids occur along the coasts of South and North America, southern Africa, and the western Mediterranean. The lack of records from other parts of the world is "almost certainly" due to a lack of appropriate sampling, rather than a true absence. Description Mystacocarids are tiny crustaceans, less than long, that live ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Branchiura
The family Argulidae, whose members are commonly known as carp lice or fish lice, are parasitic crustaceans in the class Ichthyostraca. It is the only family in the monotypic subclass Branchiura and the order Arguloida, although a second family, Dipteropeltidae, has been proposed. Although they are thought to be primitive forms, they have no fossil record. Taxonomy Branchiurans were once thought to be copepods but are now recognised as a separate subclass due to their distinct morphological characteristics.Alan P. Covich, ... D. Christopher Rogers, in Ecology and Classification of North American Freshwater Invertebrates (Third Edition), 2010 There are approximately 170 species in four genera recognised in the family Branchiura. The centres of diversity are the Afrotropical and Neotropical realms. Description Branchiurans have a flattened, oval body, which is almost entirely covered by a broad, oval carapace, four pairs of swimming legs, a pair of anterior compound eyes, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barnacle
A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile (nonmobile) and most are suspension feeders, but those in infraclass Rhizocephala are highly specialized parasites on crustaceans. They have four nektonic (active swimming) larval stages. Around 1,000 barnacle species are currently known. The name is Latin, meaning "curl-footed". The study of barnacles is called cirripedology. Description Barnacles are encrusters, attaching themselves temporarily to a hard substrate or a symbiont such as a whale ( whale barnacles), a sea snake ('' Platylepas ophiophila''), or another crustacean, like a crab or a lobster (Rhizocephala). The most common among them, "acorn barnacles" ( Sessilia), are sessile where they grow their shells directly onto the substrate. Peduncul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copepod
Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor), a number of species have parasitic phases, and some continental species may live in limnoterrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests, bogs, springs, ephemeral ponds, and puddles, damp moss, or water-filled recesses (phytotelmata) of plants such as bromeliads and pitcher plants. Many live underground in marine and freshwater caves, sinkholes, or stream beds. Copepods are sometimes used as Ecological indicator, biodiversity indicators. As with other crustaceans, copepods have a larval form. For copepods, the egg hatches into a Crustacean larvae#Nauplius, nauplius form, with a head and a tail but no true thorax or abdomen. The larva molts several times until it resembles the adult an ... [...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 is u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
