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Myozona
Macrostomorpha is a clade of free living flatworms ranked either as class or subclass in the group Rhabditophora. There are about 260 described species in two orders - marine, freshwater and brackish Macrostomida, which group most of the species diversity, and exclusively marine Haplopharyngida ''Haplopharynx'' is a genus of small, free living marine flatworms found in the North Atlantic and the Mediterranean. It is the only genus in the monotypic family Haplopharyngidae. Species The following species are recognized in the genus ''Hap ... with only three described species. Macrostomorpha constitute a basal group in Rhabditophora, showing such plesiomorphic condition as entolecithal eggs and spiral cleavage. Another trait found among members of the clade is presence of hard stylet in the male copulatory organ. References Turbellaria Rhabditophora {{flatworm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bradynectes
Macrostomorpha is a clade of free living flatworms ranked either as class or subclass in the group Rhabditophora. There are about 260 described species in two orders - marine, freshwater and brackish Macrostomida, which group most of the species diversity, and exclusively marine Haplopharyngida ''Haplopharynx'' is a genus of small, free living marine flatworms found in the North Atlantic and the Mediterranean. It is the only genus in the monotypic family Haplopharyngidae. Species The following species are recognized in the genus ''Hap ... with only three described species. Macrostomorpha constitute a basal group in Rhabditophora, showing such plesiomorphic condition as entolecithal eggs and spiral cleavage. Another trait found among members of the clade is presence of hard stylet in the male copulatory organ. References Turbellaria Rhabditophora {{flatworm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myozona
Macrostomorpha is a clade of free living flatworms ranked either as class or subclass in the group Rhabditophora. There are about 260 described species in two orders - marine, freshwater and brackish Macrostomida, which group most of the species diversity, and exclusively marine Haplopharyngida ''Haplopharynx'' is a genus of small, free living marine flatworms found in the North Atlantic and the Mediterranean. It is the only genus in the monotypic family Haplopharyngidae. Species The following species are recognized in the genus ''Hap ... with only three described species. Macrostomorpha constitute a basal group in Rhabditophora, showing such plesiomorphic condition as entolecithal eggs and spiral cleavage. Another trait found among members of the clade is presence of hard stylet in the male copulatory organ. References Turbellaria Rhabditophora {{flatworm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhabditophora
Rhabditophora (from ''rhabdito''-, rhabdite + Greek -φορος ''phoros'' bearer, i.e., "rhabdite bearers") is a class of flatworms. It includes all parasitic flatworms (clade Neodermata) and most free-living species that were previously grouped in the now obsolete class Turbellaria. Therefore, it contains the majority of the species in the phylum Platyhelminthes, excluding only the catenulids, to which they appear to be the sister group. The clade Rhabditophora was originally erected by Ulrich Ehlers in 1985Ehlers, U. (1985) ''Phylogenetic relationships within the Platyhelminthes''. ''In'' S. Conway Morris; J. D. George; R. Gibson; H. M. Platt (Eds.), ''The origins and relationships of lower invertebrates''. Oxford, Clarendon Press, p. 143-158. based on morphological analyses and its monophyly was later confirmed by molecular studies. Description Rhabditophorans are characterized by the presence of lamellated rhabdites, rodlike granules secreted in the cells of the epidermis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrostomum Lignano
''Macrostomum lignano'' is a free-living, hermaphroditic flatworm. It is transparent and of small size (adults reaching about 1.7 mm), and is part of the intertidal sand meiofauna of the Adriatic Sea. Originally a model organism for research on developmental biology and the evolution of the bilaterian body plan, it has since expanded to other important fields of research such as sexual selection and sexual conflicts, ageing and the evolution of the bilaterian body plan, ecotoxicology, and, more recently, genomics. Name The genus name "''Macrostomum''", meaning "big-mouthed", derives from the Greek μάκρος ''makros'', "large", and στόμα, ''stoma'', mouth. The species name, ''lignano'', comes from the location where this species has so far been found, the sandy beaches and lagoons at and near Lignano Sabbiadoro, Italy. Biology ''Macrostomum lignano'', like all other flatworms, is an unsegmented, soft-bodied bilaterian without body cavity, and no specialized cir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haplopharyngidae
''Haplopharynx'' is a genus of small, free living marine flatworms found in the North Atlantic and the Mediterranean. It is the only genus in the monotypic family Haplopharyngidae. Species The following species are recognized in the genus ''Haplopharynx'': * ''Haplopharynx quadristimulus'' Ax, 1971 * ''Haplopharynx rostratus'' Meixner, 1938 * ''Haplopharynx papii'' Schockaert, 2014 Anatomy Subterminal mouth leads to the simple pharynx, which subsequently continues as an intestine with terminal anal pore. A short retractable proboscis is present anteriorly to the pharynx. Variable number of glands producing rhabdites open at the surface of proboscis. Nervous system built similarly as in Macrostomida. ''Haplopharynx'' are hermaphroditic, with separate male and female gonopores. Male copulatory organ is equipped with hard, sclerotised stylet and set of needles. Reproduction and development Copulation lead to the internal fertilization. Egg is entolecithal and show spiral Cleavage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrostomida
Macrostomidaevan Beneden, E. 1870. Étude zoologique et anatomique du genre ''Macrostomum'' comprenant la description de deux especes nouvelles. Bulletin de l'Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique 30:116-133, one plate. is a family of small basal free-living flatworms, and are found in marine, brackish, and freshwater environments. There are currently about 180 named species in this family.Tyler, S., Schilling, S., Hooge, M., and Bush L. F. (comp.) (2006-2009) Turbellarian taxonomic database. Version 1.5 Description Species of the family Macrostomidae are small (~0.5 to 5 mm in length) and generally highly transparent microturbellarians. They are usually round in cross section, and with only the largest forms being dorso-ventrally flattened. They are distinguished from related animals by the possession of a simple pharynx and intestine, a single pair of lateral nerve cords, and by the absence of a statocyst. Ecology and distribution Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Class (biology)
In biological classification, class ( la, classis) is a taxonomic rank, as well as a taxonomic unit, a taxon, in that rank. It is a group of related taxonomic orders. Other well-known ranks in descending order of size are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order. History The class as a distinct rank of biological classification having its own distinctive name (and not just called a ''top-level genus'' ''(genus summum)'') was first introduced by the French botanist Joseph Pitton de Tournefort in his classification of plants that appeared in his ''Eléments de botanique'', 1694. Insofar as a general definition of a class is available, it has historically been conceived as embracing taxa that combine a distinct ''grade'' of organization—i.e. a 'level of complexity', measured in terms of how differentiated their organ systems are into distinct regions or sub-organs—with a distinct ''type'' of construction, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subclass (biology)
In biological classification, class ( la, classis) is a taxonomic rank, as well as a taxonomic unit, a taxon, in that rank. It is a group of related taxonomic orders. Other well-known ranks in descending order of size are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order. History The class as a distinct rank of biological classification having its own distinctive name (and not just called a ''top-level genus'' ''(genus summum)'') was first introduced by the French botanist Joseph Pitton de Tournefort in his classification of plants that appeared in his ''Eléments de botanique'', 1694. Insofar as a general definition of a class is available, it has historically been conceived as embracing taxa that combine a distinct ''grade'' of organization—i.e. a 'level of complexity', measured in terms of how differentiated their organ systems are into distinct regions or sub-organs—with a distinct ''type'' of construction, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haplopharyngida
''Haplopharynx'' is a genus of small, free living marine flatworms found in the North Atlantic and the Mediterranean. It is the only genus in the monotypic family Haplopharyngidae. Species The following species are recognized in the genus ''Haplopharynx'': * ''Haplopharynx quadristimulus'' Ax, 1971 * ''Haplopharynx rostratus'' Meixner, 1938 * ''Haplopharynx papii'' Schockaert, 2014 Anatomy Subterminal mouth leads to the simple pharynx, which subsequently continues as an intestine with terminal anal pore. A short retractable proboscis is present anteriorly to the pharynx. Variable number of glands producing rhabdites open at the surface of proboscis. Nervous system built similarly as in Macrostomida. ''Haplopharynx'' are hermaphroditic, with separate male and female gonopores. Male copulatory organ is equipped with hard, sclerotised stylet and set of needles. Reproduction and development Copulation lead to the internal fertilization. Egg is entolecithal and show spiral Cleavage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basal (phylogenetics)
In phylogenetics, basal is the direction of the ''base'' (or root) of a phylogenetic tree#Rooted tree, rooted phylogenetic tree or cladogram. The term may be more strictly applied only to nodes adjacent to the root, or more loosely applied to nodes regarded as being close to the root. Note that extant taxa that lie on branches connecting directly to the root are not more closely related to the root than any other extant taxa. While there must always be two or more equally "basal" clades sprouting from the root of every cladogram, those clades may differ widely in taxonomic rank, Phylogenetic diversity, species diversity, or both. If ''C'' is a basal clade within ''D'' that has the lowest rank of all basal clades within ''D'', ''C'' may be described as ''the'' basal taxon of that rank within ''D''. The concept of a 'key innovation' implies some degree of correlation between evolutionary innovation and cladogenesis, diversification. However, such a correlation does not make a given ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symplesiomorphy
In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, and synapomorphy, all mean a trait shared between species because they share an ancestral species. Apomorphic and synapomorphic characteristics convey much information about evolutionary clades and can be used to define taxa. However, plesiomorphic and symplesiomorphic characteristics cannot. The term ''symplesiomorphy'' was introduced in 1950 by German entomologist Willi Hennig. Examples A backbone is a plesiomorphic trait shared by birds and mammals, and does not help in placing an animal in one or the other of these two clades. Birds and mammals share this trait because both clades are descended from the same far distant ancestor. Other clades, e.g. snakes, lizards, turtles, fish, frogs, all have backbones and none are either birds nor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cleavage (embryo)
In embryology, cleavage is the division of cells in the early development of the embryo, following fertilization. The zygotes of many species undergo rapid cell cycles with no significant overall growth, producing a cluster of cells the same size as the original zygote. The different cells derived from cleavage are called blastomeres and form a compact mass called the morula. Cleavage ends with the formation of the blastula, or of the blastocyst in mammals. Depending mostly on the concentration of yolk in the egg, the cleavage can be holoblastic (total or entire cleavage) or meroblastic (partial cleavage). The pole of the egg with the highest concentration of yolk is referred to as the vegetal pole while the opposite is referred to as the animal pole. Cleavage differs from other forms of cell division in that it increases the number of cells and nuclear mass without increasing the cytoplasmic mass. This means that with each successive subdivision, there is roughly half the cyto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
