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Pseudotriakidae
The Pseudotriakidae are a small family of ground sharks, belonging to the order Carcharhiniformes, containing the false catsharks (genera '' Pseudotriakis'' and '' Planonasus'') and gollumsharks (genus ''Gollum''). It contains the only ground shark species that exhibit intrauterine oophagy, in which developing fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal dev ...es are nourished by eggs produced by their mother. Undescribed species One undescribed species is known - one in the genus ''Gollum'', (''Gollum'' sp. B) - the white-marked gollumshark.Weigmann, S., Stehmann, M.F.W. & Thiel, R. (2013): ''Planonasus parini'' n. g. and n. sp., a new genus and species of false cat sharks (Carchariniformes, Pseudotriakidae) from the deep northwestern Indian Ocean off Socotra Islands. ''Z ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudotriakidae
The Pseudotriakidae are a small family of ground sharks, belonging to the order Carcharhiniformes, containing the false catsharks (genera '' Pseudotriakis'' and '' Planonasus'') and gollumsharks (genus ''Gollum''). It contains the only ground shark species that exhibit intrauterine oophagy, in which developing fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal dev ...es are nourished by eggs produced by their mother. Undescribed species One undescribed species is known - one in the genus ''Gollum'', (''Gollum'' sp. B) - the white-marked gollumshark.Weigmann, S., Stehmann, M.F.W. & Thiel, R. (2013): ''Planonasus parini'' n. g. and n. sp., a new genus and species of false cat sharks (Carchariniformes, Pseudotriakidae) from the deep northwestern Indian Ocean off Socotra Islands. ''Z ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carcharhiniformes
Carcharhiniformes , the ground sharks, are the largest order of sharks, with over 270 species. They include a number of common types, such as catsharks, swellsharks, and the sandbar shark. Members of this order are characterized by the presence of a nictitating membrane over the eye, two dorsal fins, an anal fin, and five gill slits. The families in the order Carcharhiniformes are expected to be revised; recent DNA studies show that some of the conventional groups are not monophyletic. The oldest members of the order appeared during the Middle-Late Jurassic, which have teeth and bodyforms that are morphologically similar to living catsharks. Carchariniformes first underwent major diversification during the Late Cretaceous, initially as small-sized forms, before radiating into medium and large body sizes during the Cenozoic. Families According to FishBase, the nine families of ground sharks are: [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
False Catshark
The false catshark or sofa shark (''Pseudotriakis microdon'') is a species of ground shark in the family Pseudotriakidae, and the sole member of its genus. It has a worldwide distribution, and has most commonly been recorded close to the bottom over continental and insular slopes, at depths of . Reaching in length, this heavy-bodied shark can be readily identified by its elongated, keel-like first dorsal fin. It has long, narrow eyes and a large mouth filled with numerous tiny teeth. It is usually dark brown in color, though a few are light gray. With flabby muscles and a large oily liver, the false catshark is a slow-moving predator and scavenger of a variety of fishes and invertebrates. It has a viviparous mode of reproduction, featuring an unusual form of oophagy in which the developing embryos consume ova or egg fragments released by the mother and use the yolk material to replenish their external yolk sacs for later use. This species typically gives birth to two pups at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slender Smooth-hound
The slender smooth-hound or gollumshark (''Gollum attenuatus'') is a species of ground shark in the family Pseudotriakidae. It is endemic to the waters around New Zealand, where it is usually found close to the bottom over the continental slope at depths of . An extremely slim, plain brownish shark reaching in length, the slender smooth-hound can be identified by its broad, flattened head with a long, distinctively bell-shaped snout. Its mouth is angular with short furrows at the corners, and contains a very high number of tooth rows in both jaws. Its two dorsal fins are roughly equal in size. The diet of the slender smooth-hound is diverse, but dominated by small, benthic bony fishes and decapod crustaceans. It exhibits a specialized form of aplacental viviparity with oophagy: the females produce a single capsule in each uterus that contains 30–80 ova, of which one ovum develops into an embryo that consumes the rest of the ova and stores the yolk material in its external ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudotriakis
The false catshark or sofa shark (''Pseudotriakis microdon'') is a species of ground shark in the family Pseudotriakidae, and the sole member of its genus. It has a worldwide distribution, and has most commonly been recorded close to the bottom over continental and insular slopes, at depths of . Reaching in length, this heavy-bodied shark can be readily identified by its elongated, keel-like first dorsal fin. It has long, narrow eyes and a large mouth filled with numerous tiny teeth. It is usually dark brown in color, though a few are light gray. With flabby muscles and a large oily liver, the false catshark is a slow-moving predator and scavenger of a variety of fishes and invertebrates. It has a viviparous mode of reproduction, featuring an unusual form of oophagy in which the developing embryos consume ova or egg fragments released by the mother and use the yolk material to replenish their external yolk sacs for later use. This species typically gives birth to two pups at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gollum (genus)
''Gollum'' is a genus of ground sharks in the family Pseudotriakidae, native to the southwestern Pacific Ocean. The genus was described in 1973 by biologist Leonard Compagno, who named it named after the character Gollum from J. R. R. Tolkien's works, noting the species ''Gollum attenuatus'' (the slender smooth-hound) "bears some resemblance in form and habits". Species The currently described species and one undescribed species in this genus are: * ''G. attenuatus'' ( Garrick, 1954) (slender smooth-hound) * ''G. suluensis'' Last A last is a mechanical form shaped like a human foot. It is used by shoemakers and cordwainers in the manufacture and repair of shoes. Lasts typically come in pairs and have been made from various materials, including hardwoods, cast iron ... & Gaudiano, 2011 ( Sulu gollumshark) * ''Gollum'' sp. B not yet described (white-marked gollumshark) See also * '' Aenigmachanna gollum'', a species of fish named after the same character from Tolkie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planonasus
''Planonasus'' is a genus of ground sharks in the family Pseudotriakidae, native to the western Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by .... Species There are currently two species in this genus: * ''P. parini'' ( Weigmann, Stehmann & Thiel, 2013) ( dwarf false catshark) * ''P. indicus'' ( Ebert, Akhilesh, & Weigmann, 2018) ( pygmy false catshark) References Shark genera {{Shark-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oophagy
Oophagy ( ) sometimes ovophagy, literally "egg eating", is the practice of embryos feeding on eggs produced by the ovary while still inside the mother's uterus. The word oophagy is formed from the classical Greek (, "egg") and classical Greek (, "to eat"). In contrast, adelphophagy is the cannibalism of a multi-celled embryo. Oophagy is thought to occur in all sharks in the order Lamniformes and has been recorded in the bigeye thresher (''Alopias superciliosus''), the pelagic thresher (''A. pelagicus''), the shortfin mako (''Isurus oxyrinchus'') and the porbeagle (''Lamna nasus'') among others. It also occurs in the tawny nurse shark (''Nebrius ferrugineus''), and in the family Pseudotriakidae. This practice may lead to larger embryos or prepare the embryo for a predatory lifestyle. There are variations in the extent of oophagy among the different shark species. The grey nurse shark (''Carcharias taurus'') practices intrauterine cannibalism, the first developed embryo consumi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theodore Gill
Theodore Nicholas Gill (March 21, 1837 – September 25, 1914) was an American ichthyologist, mammalogist, malacologist and librarian. Career Born and educated in New York City under private tutors, Gill early showed interest in natural history. He was associated with J. Carson Brevoort in the arrangement of the latter's entomological and ichthyological collections before going to Washington D.C. in 1863 to work at the Smithsonian Institution. He catalogued mammals, fishes and mollusks most particularly although maintaining proficiency in other orders of animals. He was librarian at the Smithsonian and also senior assistant to the Library of Congress. He was elected as a member of the American Philosophical Society in 1867. Gill was professor of zoology at George Washington University. He was also a member of the Megatherium Club at the Smithsonian Institution in Washington, D.C. Fellow members frequently mocked him for his vanity. He was president of the American Associat ... [...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] |
Fetus
A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal development begins from the ninth week after fertilization (or eleventh week gestational age) and continues until birth. Prenatal development is a continuum, with no clear defining feature distinguishing an embryo from a fetus. However, a fetus is characterized by the presence of all the major body organs, though they will not yet be fully developed and functional and some not yet situated in their final anatomical location. Etymology The word '' fetus'' (plural '' fetuses'' or '' feti'') is related to the Latin '' fētus'' ("offspring", "bringing forth", "hatching of young") and the Greek "φυτώ" to plant. The word "fetus" was used by Ovid in Metamorphoses, book 1, line 104. The predominant British, Irish, and Commonwealth spelling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shark Families
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the rays. However, the term "shark" has also been used to refer to all extinct members of Chondrichthyes with a shark-like morphology, such as hybodonts and xenacanths. The oldest modern sharks are known from the Early Jurassic. They range in size from the small dwarf lanternshark (''Etmopterus perryi''), a deep sea species that is only in length, to the whale shark (''Rhincodon typus''), the largest fish in the world, which reaches approximately in length. Sharks are found in all seas and are common to depths up to . They generally do not live in freshwater, although there are a few known exceptions, such as the bull shark and the river shark, which can be found in both seawater and fres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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