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Rhabdocoela
Rhabdocoela is an order of flatworms in the class Rhabditophora with about 1700 species described worldwide. The order was first described in 1831 by Christian Gottfried Ehrenberg. Most of rhabdocoels are free-living organisms, but some live symbiotically with other animals. Description Although Rhabdocoela is a highly supported group in molecular studies, there is no clear morphological synapomorphy that unites them. All rhabdocoels have a bulbous pharynx, but this is shared with other flatworm groups, such as Neodermata, Lecithoepitheliata and some species of Prolecithophora. Some possibly identified synapomorphies are found in the ultrastructure of the protonephridial system, but similar constructions exist in other groups. Another possible apomorphy is found in the ultrastructure of the sperm, which has a dense heel on the basal bodies during spermiogenesis, but some groups have lost this feature. Classification Rhabdocoels were traditionally classified in two groups, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhabdocoela
Rhabdocoela is an order of flatworms in the class Rhabditophora with about 1700 species described worldwide. The order was first described in 1831 by Christian Gottfried Ehrenberg. Most of rhabdocoels are free-living organisms, but some live symbiotically with other animals. Description Although Rhabdocoela is a highly supported group in molecular studies, there is no clear morphological synapomorphy that unites them. All rhabdocoels have a bulbous pharynx, but this is shared with other flatworm groups, such as Neodermata, Lecithoepitheliata and some species of Prolecithophora. Some possibly identified synapomorphies are found in the ultrastructure of the protonephridial system, but similar constructions exist in other groups. Another possible apomorphy is found in the ultrastructure of the sperm, which has a dense heel on the basal bodies during spermiogenesis, but some groups have lost this feature. Classification Rhabdocoels were traditionally classified in two groups, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dalytyphloplanida
Dalytyphloplanida is a suborder of rhabdocoel flatworms. It contains about 1000 species and has a cosmopolitan distribution in both marine and freshwater environments, with several groups having commensal or parasitic lifestyles. Description The suborder Dalytyphloplanida was recently erected based on molecular evidences and few synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ... are known. The possible identified synapomorphies include the presence of small dense granules, as well as an axonemal spur and a group of longitudinal microtubules in sperm cells. Classification Traditionally, members of the suborder Dalytyphloplanida were classified into two groups: Dalyellioida and Typhloplanoida, although both were poorly characterized morphologically. Recent molec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kalyptorhynchia
Kalyptorhynchia is a suborder of rhabdocoel flatworms. It contains almost 600 species and has a cosmopolitan distribution. Description All kalyptorhynchs have an anterior muscular proboscis which is used to capture prey. The proboscis is located inside an invagination of the epidermis called the proboscis-sheath that is closed by a sphincter at the tip of the body. Another synapomorphy supporting the group is the incorporation of the axonemes within the cell body of sperm cells during spermiogenesis Spermiogenesis is the final stage of spermatogenesis, during which the spermatids develop into mature spermatozoa. At the beginning of the stage, the spermatid is a more or less circular cell containing a nucleus, Golgi apparatus, centriole and .... Classification Kalyptorhynchs are traditionally classified into two infraorders: Eukalyptorhynchia, with a cone-shaped proboscis, and Schizorhynchia, with a proboscis formed by two opposite parallel muscular sheets. However, mole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Typhloplanidae
Typhloplanidae is a family of flatworms in the order Rhabdocoela. It is one of the most species-rich families of Rhabdocoela, comprising around 300 species. They inhabit freshwater, estuarine, marine and terrestrial habitats. They can be benthic or pelagic. Typhloplanidae are predatory. They can reach high densities in their habitats. Most representatives are 1 to 5 mm in length, but a few species, like ''Mesostoma ehrenbergii ''Mesostoma ehrenbergii'' is a species of rhabdocoel flatworms in the family Typhloplanidae. Description The species is comparatively large for microturbellarians, reaching 1,5 cm in body length. Its body is highly transparent. It is dorsov ...'', can reach up to 1.5 cm. Subfamilies and genera (incomplete): * Subfamily Ascophorinae Findenegg, 1924 * Subfamily Mesophaenocorinae Norena, Brusa, Ponce de Leon & Damborenea, 2005 * Subfamily Mesostominae Hyman, 1955 ** Genus '' Bothromesostoma'' Braun, 1885 ** Genus '' Mesostoma'' Ehrenberg, 1837 * Sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flatworms
The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates. Unlike other bilaterians, they are acoelomates (having no body cavity), and have no specialized circulatory and respiratory organs, which restricts them to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, the food cannot be processed continuously. In traditional medicinal texts, Platyhelminthes are divided into Turbellaria, which are mostly non-parasitic animals such as planarians, and three entirely parasitic groups: Cestoda, Trematoda and Monogenea; however, since the turbellarians have since been proven not to be mono ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prolecithophora
The ''Prolecithophora'' are an order consisting of an estimated 300 species of small (typically 0.2 – 12 mm, one species up to 50 mm), active, aquatic flatworms. The order lacks a common English name. Most species are shaped like an elongated, stylized droplet, and are opaque white or yellow; they frequently have contrasting bands or spots in colors, such as purple, yellow, red, or brown. They have no to three (normally two) pairs of pigment-cup eyes, and well-developed tactile and chemoreceptor senses. With few exceptions, species are protandric hermaphrodites with internal fertilization. Egg capsules are, according to species, glued to various hard surfaces; the young hatch as miniature copies of their parents. Ecology All prolecithophorans are aquatic, with most living in the oceans. Some species, especially those living in freshwater, are predators and scavengers, but many marine species are associated with colonial animals such as bryozoans or live as symbiont ... [...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] |
Fecampiida
Fecampiida is an order of flatworms in the class Rhabditophora. It is a considerably recent clade, erected after molecular studies. Description The order Fecampiida, as currently defined, was erected based on molecular studies. They all are parasitic organisms and are united by a similar development of the basal bodies during spermiogenesis. Classification Three families of Fecampiida were initially classified in different flatworm orders: Urastomatidae and Genostomatidae were considered prolecithophorans, while Fecampiidae was considered a rhabdocoel. When the genus '' Notentera'' was discovered, its relationship with Fecampiidae was clear based on morphology, and both groups were united under Fecampiida. Further ultrastructural studies suggested that Urastomatidae and Genostomatidae were closely related to Fecampiidae and Notenteridae, which was confirmed by molecular studies. Due to similarities in the protonephridial flame bulb, sperm and spermiogenesis, as well as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neodermata
Neodermata is a clade of rhabditophoran flatworms containing the parasitic groups Trematoda, Monogenea and Cestoda. Description All neodermatans are parasites, in many groups having a free-swimming larval stage. The most striking feature uniting all neodermatans is that the ciliated epidermis (typical of most flatworms) is cast off in adult worms, being replaced by a syncytium called tegument or ''neodermis''. Other characters found in all neodermatans are related to the anatomy of the protonephridium and the rootlets of epidermal locomotory cilia. Phylogeny Currently, the monophyly of Neodermata is undisputed, being supported by both morphological and molecular data. It is clear that they evolved from free-living flatworms (turbellarians), but their sister-group was for a long time a matter of debate. The first attempts to reconstruct the phylogeny of flatworms, based on morphological evidence, considered Rhabdocoela to be the sister-group of Neodermata, but this was based ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladocera
The Diplostraca or Cladocera, commonly known as water fleas, are a superorder of small crustaceans that feed on microscopic chunks of organic matter (excluding some predatory forms). Over 1000 species have been recognised so far, with many more undescribed. The oldest fossils of diplostracans date to the Jurassic, though their modern morphology suggests that they originated substantially earlier, during the Paleozoic. Some have also adapted to a life in the ocean, the only members of Branchiopoda to do so, even if several anostracans live in hypersaline lakes. Most are long, with a down-turned head with a single median compound eye, and a carapace covering the apparently unsegmented thorax and abdomen. Most species show cyclical parthenogenesis, where asexual reproduction is occasionally supplemented by sexual reproduction, which produces resting eggs that allow the species to survive harsh conditions and disperse to distant habitats. Description They are mostly long, with t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temnocephalida
The Temnocephalida are an order of turbellarian flatworms. Unlike most other turbellarians, all the species in this order are either commensal or parasitic. They can be found living on crustaceans, molluscs, and, in some species, even turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked tu ...s. The commensal species typically live in the gill or mantle cavities of their hosts, while the parasites live inside the digestive system. Anatomically, temnocephalidans can be distinguished from related groups by the presence of an adhesive disc on the underside for attachment to the host, and of a number of finger-like projections arising from the head. References External links Turbellaria {{flatworm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arthropod cuticle, cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. Arthropods are bilaterally symmetrical and their body possesses an exoskeleton, external skeleton. In order to keep growing, they must go through stages of moulting, a process by which they shed their exoskeleton to reveal a new one. Some species have wings. They are an extremely diverse group, with up to 10 million species. The haemocoel, an arthropod's internal cavity, through which its haemolymph – analogue of blood – circulates, accommodates its interior Organ (anatomy), organs; it has an open circulatory system. Like their exteriors, the internal or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
