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Bothrioplanida
''Bothrioplana'' is a genus of freshwater flatworms, the sole genus in the family Bothrioplanidae and order Bothrioplanida. Description Species of ''Bothrioplana'' are small organisms, usually measuring 2–3 mm in length, but reaching up to 7 mm. The body is transparent, elongate, with a round posterior end and a truncate front end, and lacks eyes. The mouth lies on the ventral side at about the middle of the body, as in most turbellarians, and has a short pharynx. The intestine is tripartite, similarly to what occurs in triclads, having one anterior and two posterior branches. The posterior branches unite behind the copulatory apparatus and form a single branch. The reproductive system has a pair of testes and a pair of ovaries, as well as a series of vitellaria (yolk-producing glands) that extend along the entire body. Many specimens have the male reproductive system highly reduced or even absent. As a result, parthenogenesis may occur. Ecology Individuals of ''Bothriopl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bothrioplana Semperi
''Bothrioplana'' is a genus of freshwater flatworms, the sole genus in the family Bothrioplanidae and order Bothrioplanida. Description Species of ''Bothrioplana'' are small organisms, usually measuring 2–3 mm in length, but reaching up to 7 mm. The body is transparent, elongate, with a round posterior end and a truncate front end, and lacks eyes. The mouth lies on the ventral side at about the middle of the body, as in most turbellarians, and has a short pharynx. The intestine is tripartite, similarly to what occurs in triclads, having one anterior and two posterior branches. The posterior branches unite behind the copulatory apparatus and form a single branch. The reproductive system has a pair of testes and a pair of ovaries, as well as a series of vitellaria (yolk-producing glands) that extend along the entire body. Many specimens have the male reproductive system highly reduced or even absent. As a result, parthenogenesis may occur. Ecology Individuals of ''Bothrio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bothrioplana Sinensis
''Bothrioplana'' is a genus of freshwater flatworms, the sole genus in the family Bothrioplanidae and order Bothrioplanida. Description Species of ''Bothrioplana'' are small organisms, usually measuring 2–3 mm in length, but reaching up to 7 mm. The body is transparent, elongate, with a round posterior end and a truncate front end, and lacks eyes. The mouth lies on the ventral side at about the middle of the body, as in most turbellarians, and has a short pharynx. The intestine is tripartite, similarly to what occurs in triclads, having one anterior and two posterior branches. The posterior branches unite behind the copulatory apparatus and form a single branch. The reproductive system has a pair of testes and a pair of ovaries, as well as a series of vitellaria (yolk-producing glands) that extend along the entire body. Many specimens have the male reproductive system highly reduced or even absent. As a result, parthenogenesis may occur. Ecology Individuals of ''Bothrio ... [...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] |
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] |
Turbellarian
The Turbellaria are one of the traditional sub-divisions of the phylum Platyhelminthes (flatworms), and include all the sub-groups that are not exclusively parasitic. There are about 4,500 species, which range from to large freshwater forms more than long or terrestrial species like ''Bipalium kewense'' which can reach in length. All the larger forms are flat with ribbon-like or leaf-like shapes, since their lack of respiratory and circulatory systems means that they have to rely on diffusion for internal transport of metabolites. However, many of the smaller forms are round in cross section. Most are predators, and all live in water or in moist terrestrial environments. Most forms reproduce sexually and with few exceptions all are simultaneous hermaphrodites. The Acoelomorpha and the genus ''Xenoturbella'' were formerly included in the Turbellaria, but are no longer regarded as Platyhelminthes. All the exclusively parasitic Platyhelminthes form a monophyletic group Neodermat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pharynx
The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its structure varies across species. The pharynx carries food and air to the esophagus and larynx respectively. The flap of cartilage called the epiglottis stops food from entering the larynx. In humans, the pharynx is part of the digestive system and the conducting zone of the respiratory system. (The conducting zone—which also includes the nostrils of the nose, the larynx, trachea, bronchi, and bronchioles—filters, warms and moistens air and conducts it into the lungs). The human pharynx is conventionally divided into three sections: the nasopharynx, oropharynx, and laryngopharynx. It is also important in vocalization. In humans, two sets of pharyngeal muscles form the pharynx and determine the shape of its lumen. They are arranged as an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tricladida
A planarian is one of the many flatworms of the traditional class Turbellaria. It usually describes free-living flatworms of the order Tricladida (triclads), although this common name is also used for a wide number of free-living platyhelminthes. Planaria are common to many parts of the world, living in both saltwater and freshwater ponds and rivers. Some species are terrestrial and are found under logs, in or on the soil, and on plants in humid areas. The triclads are characterized by triply branched intestine and anteriorly situated ovaries, next to the brain. Today the order Tricladida is split into three suborders, according to their phylogenetic relationships: Maricola, Cavernicola and Continenticola. Formerly, the Tricladida was split according to habitats: Maricola, which is marine; Paludicola which inhabits freshwater; and Terricola, which is land-dwelling. Planaria exhibit an extraordinary ability to regenerate lost body parts. For example, a planarian split lengt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parthenogenesis
Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development of embryos occur in a gamete (egg or sperm) without combining with another gamete (e.g., egg and sperm fusing). In animals, parthenogenesis means development of an embryo from an unfertilized Gametophyte, egg cell. In plants, parthenogenesis is a component process of apomixis. In algae, parthenogenesis can mean the development of an embryo from either an individual sperm or an individual egg. Parthenogenesis occurs naturally in some plants, algae, invertebrate animal species (including nematodes, some tardigrades, water fleas, some scorpions, aphids, some mites, some bees, some Phasmatodea and parasitic wasps) and a few vertebrates (such as some fish, amphibians, reptiles and birds). This type of reproduction has been induced artificially ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daphnia
''Daphnia'' is a genus of small planktonic crustaceans, in length. ''Daphnia'' are members of the order Anomopoda, and are one of the several small aquatic crustaceans commonly called water fleas because their saltatory swimming style resembles the movements of fleas. ''Daphnia'' spp. live in various aquatic environments ranging from acidic swamps to freshwater lakes and ponds. The two most commonly found species of ''Daphnia'' are '' D. pulex'' (small and most common) and '' D. magna'' (large). They are often associated with a related genus in the order Cladocera: ''Moina'', which is in the Moinidae family instead of the Daphniidae, and is much smaller than ''D. pulex'' (roughly half the maximum length). Appearance and characteristics The body of a ''Daphnia'' species is usually long, and is divided into segments, although this division is not visible. The head is fused, and is generally bent down towards the body with a visible notch separating the two. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proseriata
Proseriata is an order of free-living flatworms in the class Rhabditophora with over 400 species described worldwide. Description Proseriate flatworms are minute aquatic organisms, usually with an elongate body. There are no strong synapomorphies for the group, but it is supported by molecular studies. The suggested synapomorphies include the lack of lamellated rhabdites, an otherwise synapomorphy of Rhabditophora, and some features of the ultrastructure of the protonephridia and the cilia of epidermal cells. Ecology Most proseriates occur in marine environments, at the coastal zones, and are particularly common in high-energy habitats with medium to coarse sediments, sometimes being the dominant animal group in such areas. They are also common in brackish water, but few species occur in freshwater. Most proseriates are carnivores or scavengers, but some species are ectoparasitic on marine crustaceans. As they occur in very high densities in some habitats, they may have a co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
