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Hansenocaris Corvinae
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 remai ... [...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] |
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] |
Raffles Bulletin Of Zoology
''The Raffles Bulletin of Zoology'' is a peer-reviewed open-access scientific journal published by the Lee Kong Chian Natural History Museum at the National University of Singapore. It covers the taxonomy, ecology, and conservation of Southeast Asian fauna.Supplements are published as and when funding permits and may cover topics that extend beyond the normal scope of the journal depending on the targets of the funding agency. It was established as the ''Bulletin of the Raffles Museum'' in 1928 and renamed ''Bulletin of the National Museum of Singapore'' in 1961, before obtaining its current title in 1971. See also * List of zoology journals This is a list of scientific journals which cover the field of zoology. A * '' Acta Entomologica Musei Nationalis Pragae'' * '' Acta Zoologica Academiae Scientiarum Hungaricae'' * '' Acta Zoologica Bulgarica'' * ''Acta Zoologica Mexicana'' * '' ... References Zoology journals Biannual journals Open access journals English-language ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instar
An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, changes in the number of body segments or head width. After shedding their exoskeleton (moulting), the juvenile arthropods continue in their life cycle until they either pupate or moult again. The instar period of growth is fixed; however, in some insects, like the salvinia stem-borer moth, the number of instars depends on early larval nutrition. Some arthropods can continue to moult after sexual maturity, but the stages between these subsequent moults are generally not called instars. For most insect species, an ''instar'' is the developmental stage of the larval forms of holometabolous (complete metamorphism) or nymphal forms o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abdomen
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. The area occupied by the abdomen is called the abdominal cavity. In arthropods it is the posterior (anatomy), posterior tagma (biology), tagma of the body; it follows the thorax or cephalothorax. In humans, the abdomen stretches from the thorax at the thoracic diaphragm to the pelvis at the pelvic brim. The pelvic brim stretches from the lumbosacral joint (the intervertebral disc between Lumbar vertebrae, L5 and Vertebra#Sacrum, S1) to the pubic symphysis and is the edge of the pelvic inlet. The space above this inlet and under the thoracic diaphragm is termed the abdominal cavity. The boundary of the abdominal cavity is the abdominal wall in the front and the peritoneal surface at the rear. In vertebrates, the abdomen is a large body c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalic Shield
A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron. Crustaceans In crustaceans, the carapace functions as a protective cover over the cephalothorax (i.e., the fused head and thorax, as distinct from the abdomen behind). Where it projects forward beyond the eyes, this projection is called a rostrum. The carapace is calcified to varying degrees in different crustaceans. Zooplankton within the phylum Crustacea also have a carapace. These include Cladocera, ostracods, and isopods, but isopods only have a developed "cephalic shield" carapace covering the head. Arachnids In arachnids, the carapace is formed by the fusion of prosomal tergites into a single plate which carries the eyes, ocularium, ozopores (a pair of openings of the scent gland of Opiliones) and di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Crustacean Biology
The ''Journal of Crustacean Biology'' is a quarterly peer-reviewed scientific journal in the field of carcinology (crustacean research). It is published by The Crustacean Society and Oxford University Press (formerly by Brill Publishers and Allen Press), and since 2015 the editor-in-chief has been Peter Castro. According to the ''Journal Citation Reports'', its 2016 impact factor is 1.064. The journal has a mandatory publication fee of US$ 115 per printed page for non-members of the SocietyJournal of Crustacean BiologyInstructions for Authors/ref> and an optional open access Open access (OA) is a set of principles and a range of practices through which research outputs are distributed online, free of access charges or other barriers. With open access strictly defined (according to the 2001 definition), or libre op ... fee of $1830 minimum. References Further reading * * External links {{Wikispecies-inline, ISSN 0278-0372 Carcinology journals Publications establi ... [...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] |
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] |
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] |
Sister Group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and taxon B are sister groups to each other. Taxa A and B, together with any other extant or extinct descendants of their most recent common ancestor (MRCA), form a monophyletic group, the clade AB. Clade AB and taxon C are also sister groups. Taxa A, B, and C, together with all other descendants of their MRCA form the clade ABC. The whole clade ABC is itself a subtree of a larger tree which offers yet more sister group relationships, both among the leaves and among larger, more deeply rooted clades. The tree structure shown connects through its root to the rest of the universal tree of life. In cladistic standards, taxa A, B, and C may represent specimens, species, genera, or any other taxonomic units. If A and B are at the same taxonomic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
18S Ribosomal RNA
18S ribosomal RNA (abbreviated 18S rRNA) is a part of the ribosomal RNA. The S in 18S represents Svedberg units. 18S rRNA is an SSU rRNA, a component of the eukaryotic ribosomal small subunit (40S). 18S rRNA is the structural RNA for the small component of eukaryotic cytoplasmic ribosomes, and thus one of the basic components of all eukaryotic cells. 18S rRNA is the eukaryotic cytosolic homologue of 16S ribosomal RNA in prokaryotes and plastids. 18S rRNA is also a homologue of 12S ribosomal RNA in mitochondria. The genes coding for 18S rRNA are referred to as 18S rRNA genes. Sequence data from these genes is widely used in molecular analysis to reconstruct the evolutionary history of organisms, especially in vertebrates, as its slow evolutionary rate makes it suitable to reconstruct ancient divergences. Uses in phylogeny The small subunit (SSU) 18S rRNA gene is one of the most frequently used genes in phylogenetic studies and an important marker for random target polymerase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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