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Portunoidea
__NOTOC__ Portunoidea is a superfamily of crabs that includes the family Portunidae, the swimming crabs. Which other crab families are also placed here is a matter of some contention, and may be revised following molecular phylogenetic analyses. Description Their rather flat and smooth carapace is usually wider than long and of hexagonal, subhexagonal, rectangular, or transversely ovate shape. It is usually widest between the hindmost spines of the forward rim; there may be up to 9 pairs of these spines, with a few smaller ones right above the head, but they are missing altogether in some species. In some, the first maxilliped's endopod is lobed, forming the characteristic portunid lobe. The chelipeds are usually robust, and in some the last pereiopod pair has ovate dactyls. The sutures of the sternum between segments 4 to 8 are usually incomplete, and in the Portunidae, the eighth sternite is usually visible if seen from below and has a penial groove. In males, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portunidae
Portunidae is a family of crabs which contains the swimming crabs. Description Portunid crabs are characterised by the flattening of the fifth pair of legs into broad paddles, which are used for swimming. This ability, together with their strong, sharp claws, allows many species to be fast and aggressive predators. Examples Its members include many well-known shoreline crabs, such as the European shore crab (''Carcinus maenas''), blue crab (''Callinectes sapidus''), and velvet crab ('' Necora puber''). Two genera in the family are contrastingly named ''Scylla'' and ''Charybdis''; the former contains the economically important species black crab ('' Scylla serrata'') and '' Scylla paramamosain''. Taxonomy The circumscription of the family varies, with some authors treating "Carcinidae", "Catoptridae" and "Macropipidae" as separate families, and others considering them subfamilies of a wider Portunidae. Swimming crabs reach their greatest species diversity in the Pacific and India ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geryonidae
Geryonidae is a family of crabs, including the following genera and species: *'' Chaceon'' Manning & Holthuis, 1989 **'' Chaceon affinis'' (A. Milne-Edwards & Bouvier, 1894) **'' Chaceon albus'' Davie, Ng & Dawson, 2007 **'' Chaceon alcocki'' Ghosh & Manning, 1993 **'' Chaceon atopus'' Manning & Holthuis, 1989 **'' Chaceon australis'' Manning, 1993 **'' Chaceon bicolor'' Manning & Holthuis, 1989 **'' Chaceon chilensis'' Chirino-Gálvez & Manning, 1989 **'' Chaceon chuni'' (Macpherson, 1983) **'' Chaceon collettei'' Manning, 1992 **'' Chaceon crosnieri'' Manning & Holthuis, 1989 **'' Chaceon eldorado'' Manning & Holthuis, 1989 **'' Chaceon erytheiae'' (Macpherson, 1984) **'' Chaceon fenneri'' (Manning & Holthuis, 1984) **'' Chaceon gordonae'' (Ingle, 1985) **'' Chaceon goreni'' Galil & Manning, 2001 **'' Chaceon granulatus'' (Sakai, 1978) **'' Chaceon imperialis'' Manning, 1992 **'' Chaceon inghami'' (Manning & Holthuis, 1986) **'' Chaceon inglei'' Manning & Holthuis, 1989 **'' Cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the world's oceans, in freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers. They first appeared during the Jurassic Period. Description Crabs are generally covered with a thick exoskeleton, composed primarily of highly mineralized chitin, and armed with a pair of chelae (claws). Crabs vary in size from the pea crab, a few millimeters wide, to the Japanese spider crab, with a leg span up to . Several other groups of crustaceans with similar appearances – such as king crabs and porcelain crabs – are not true crabs, but have evolved features similar to true crabs through a process known as carcinisation. Environment Crabs are found in all of the world's oceans, as well as in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ocean
The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the world ocean is conventionally divided."Ocean." ''Merriam-Webster.com Dictionary'', Merriam-Webster, [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mathildellidae
Mathildellidae is family of crabs belonging to the superfamily Goneplacoidea, containing the following genera: *'' Beuroisia'' Guinot & Richer de Forges, 1981 *†''Branchioplax ''Branchioplax'' is an extinct genus of crab which existed in Alaska and Washington during the Eocene period. It was first named by Mary Rathbun in 1916, and contains ten species, including ''Branchioplax washingtoniana'' from the Hoko River For ...'' Rathbun, 1916 *†'' Coeloma'' A. Milne-Edwards, 1865 *'' Intesius'' Guinot & Richer de Forges, 1981 *'' Mathildella'' Guinot & Richer de Forges, 1981 *'' Neopilumnoplax'' Serène, 1969 *'' Platypilumnus'' Alcock, 1894 *†'' Tehuacana'' Stenzel, 1944 References Goneplacoidea Decapod families {{Crab-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexapodidae
Hexapodidae is a family of crabs, the only family in the superfamily Hexapodoidea. It has traditionally been treated as a subfamily of the family Goneplacidae, and was originally described as a subfamily of Pinnotheridae. Its members can be distinguished from all other true crabs by the reduction of the thorax, such that only seven sternites are exposed, and only four pairs of pereiopods are present. Not counting the enlarged pair of claws, this leaves only six walking legs, from which the type genus ''Hexapus'', and therefore the whole family, takes its name. Some anomuran "crabs", such as porcelain crabs and king crabs also have only four visible pairs of legs. With the exception of '' Stevea williamsi'', from Mexico, all the extant members are found either in the Indo-Pacific oceans, or around the coast of Africa. Fossil record In addition to the extant taxa, the family contains two genera known only from fossils – '' Goniocypoda'' and '' Palaeopinnixa'' – and two fur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Family (biology)
Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as the "walnut family". What belongs to a family—or if a described family should be recognized at all—are proposed and determined by practicing taxonomists. There are no hard rules for describing or recognizing a family, but in plants, they can be characterized on the basis of both vegetative and reproductive features of plant species. Taxonomists often take different positions about descriptions, and there may be no broad consensus across the scientific community for some time. The publishing of new data and opin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contributions To Zoology
''Contributions to Zoology'' (formerly known as ''Bijdragen tot de Dierkunde'') is a scientific journal that started in 1848 as a publication of the Committee in charge of the library of the Dutch Royal Zoological Society "Natura Artis Magistra" and became integrated in the library of the University of Amsterdam in 1939. Since 2019 the journal is published by Brill publishers, Leiden. The journal has been freely available online since 1997. The current editor-in-chief is Ronald Vonk from Naturalis Biodiversity Center, Leiden. Contributions to Zoology solicits high-quality papers in all systematics-related branches of comparative zoology (including paleozoology). Preference is given to manuscripts dealing with conceptual issues and to integrative papers (e.g., ecology and biodiversity, morphology and phylogeny and character state evolution, phylogeny and historical biogeography, systematics and bioinformatics, bioinformatics and biodiversity, habitat disturbance and biogeography, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xanthoidea
Xanthoidea is a superfamily of crabs, comprising the three families Xanthidae, Panopeidae and Pseudorhombilidae. Formerly, a number of other families were included in Xanthoidea, but many of these have since been removed to other superfamilies. These include Carpilioidea, Eriphioidea, Hexapodoidea, Pilumnoidea and Trapezioidea. Even in this reduced state, Xanthoidea remains one of the most species-rich superfamilies of crabs. Families The World Register of Marine Species lists the following families: * Panopeidae Ortmann, 1893 *Pseudorhombilidae Pseudorhombilidae is a family of crabs. Genera The World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of marine organis ... Alcock, 1900 * Xanthidae MacLeay, 1838 References External links * Crabs Arthropod superfamilies {{crab-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonopod
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 morpholo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Somite
The somites (outdated term: primitive segments) are a set of bilaterally paired blocks of paraxial mesoderm that form in the embryonic stage of somitogenesis, along the head-to-tail axis in segmented animals. In vertebrates, somites subdivide into the dermatomes, myotomes, sclerotomes and syndetomes that give rise to the vertebrae of the vertebral column, rib cage, part of the occipital bone, skeletal muscle, cartilage, tendons, and skin (of the back). The word ''somite'' is sometimes also used in place of the word '' metamere''. In this definition, the somite is a homologously-paired structure in an animal body plan, such as is visible in annelids and arthropods. Development The mesoderm forms at the same time as the other two germ layers, the ectoderm and endoderm. The mesoderm at either side of the neural tube is called paraxial mesoderm. It is distinct from the mesoderm underneath the neural tube which is called the chordamesoderm that becomes the notochord. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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