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Pharyngeal Teeth
Pharyngeal teeth are teeth in the pharyngeal arch of the throat of cyprinids, suckers, and a number of other fish species otherwise lacking teeth."Suckers ''Catostomidae''" Many popular aquarium fish such as and loaches have these structures. Members of the genus '''' such as [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centrarchidae
Centrarchidae, better known as sunfishes, is a family of freshwater ray-finned fish belonging to the order Perciformes (formerly belonging to the deprecated order Centrarchiformes), native only to North America. There are eight universally included genera within the centrarchid family: ''Lepomis'' (true sunfishes), '' Micropterus'' (black basses), ''Pomoxis'' ( crappies), ''Enneacanthus'' (banded sunfishes), ''Centrarchus'' (type genus, consisting solely of the flier ''C. macropterus''), ''Archoplites'' ( Sacramento perch), ''Ambloplites'' (rock basses), and ''Acantharchus'' (mud sunfish). A genetic study in 2012 suggests that the highly distinct pygmy sunfishes of the genus '' Elassoma'' are also centarchids. The centrarchid family comprises 38 identified species, 34 of which are extant. It includes many popular game fishes familiar to North American anglers, such as the rock bass, largemouth bass, bluegill, pumpkinseed, green sunfish and crappies. Most sunfish are h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish Jaw
Most bony fishes have two sets of jaws made mainly of bone. The primary oral jaws open and close the mouth, and a second set of pharyngeal jaws are positioned at the back of the throat. The oral jaws are used to capture and manipulate prey by biting and crushing. The pharyngeal jaws, so-called because they are positioned within the pharynx, are used to further process the food and move it from the mouth to the stomach. Cartilaginous fishes, such as sharks and rays, have one set of oral jaws made mainly of cartilage. They do not have pharyngeal jaws. Generally jaws are articulated and oppose vertically, comprising an upper jaw and a lower jaw and can bear numerous ordered teeth. Cartilaginous fishes grow multiple sets ''(polyphyodont)'' and replace teeth as they wear by moving new teeth laterally from the medial jaw surface in a conveyor-belt fashion. Teeth are replaced multiple times also in most bony fishes, but unlike cartilaginous fishes, the new tooth erupts only after the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Tooth Development
Tooth development or odontogenesis is the process in which teeth develop and grow into the mouth. Tooth development varies among species. Tooth development in vertebrates Fish In fish, Hox gene expression regulates mechanisms for tooth initiation. However, sharks continuously produce new teeth throughout their lives via a drastically different mechanism. Shark teeth form from modified scales near the tongue and move outward on the jaw in rows until they are eventually dislodged. Their scales, called dermal denticles, and teeth are homologous organs. Mammals Generally, tooth development in non-human mammals is similar to human tooth development. The variations usually lie in the morphology, number, development timeline, and types of teeth. However, some mammals' teeth do develop differently than humans'. In mice, WNT signals are required for the initiation of tooth development. Rodents' teeth continually grow, forcing them to wear down their teeth by gnawing on various mater ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cichlid
Cichlids are fish from the family Cichlidae in the order Cichliformes. Cichlids were traditionally classed in a suborder, the Labroidei, along with the wrasses ( Labridae), in the order Perciformes, but molecular studies have contradicted this grouping. The closest living relative of cichlids is probably the convict blenny, and both families are classified in the 5th edition of ''Fishes of the World'' as the two families in the Cichliformes, part of the subseries Ovalentaria. This family is both large and diverse. At least 1,650 species have been scientifically described, making it one of the largest vertebrate families. New species are discovered annually, and many species remain undescribed. The actual number of species is therefore unknown, with estimates varying between 2,000 and 3,000. Many cichlids, particularly tilapia, are important food fishes, while others, such as the ''Cichla'' species, are valued game fish. The family also includes many popular freshwater ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haikouella
''Haikouella'' is an agnathan chordate from the Lower Cambrian Maotianshan Shales of Chengjiang County in Yunnan Province, China. An analysis in 2015 placed ''Haikouella'' as a junior synonym of ''Yunnanozoon,'' another Maotianshan shale Cambrian chordate''.'' It is similar to the form ''Yunnanozoon'', which is possibly a hemichordate. Still, there are anatomical differences from ''Yunnanozoon'', including a larger stomach and smaller (0.1 mm) pharyngeal teeth. ''Haikouella'' does not have bones or a movable jaw, but it otherwise resembles vertebrates. ''Haikouichthys'' and ''Myllokunmingia'', which seem to share significant fish-like characters, have been found in the same beds. Suspected hemichordates are also known from these deposits as well as from the Middle Cambrian Burgess Shale of British Columbia. Other than possible fish scales/plates from the Upper Cambrian of Wyoming, these Chinese fish-like chordates are one of the only known pre-Ordovician craniates. ''Haik ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yunnanozoon
''Yunnanozoon lividum'' (Yunnan + Greek ζῷον ''zôion'', ''lividum''; "livid animal of Yunnan") is an extinct species of possible vertebrate or chordate from the Lower Cambrian, Chengjiang biota of Yunnan province, China. It is thought of as a deuterostome suspected of being either a hemichordate or chordate. In 2022, a study reanalyzed fossils of ''Yunnanozoon'' and found it to be one of the earliest members of the vertebrate family tree. ''Yunnanozoon'' is similar to the form ''Haikouella'', which is almost certainly a chordate. Still, there are anatomical differences from ''Haikouella'', including a smaller stomach and much larger (1 mm) pharyngeal teeth. It is by no means certain whether Yunannozoon possessed features such as a heart, gills, etc., which are seen in well-preserved specimens of ''Haikouella''. ''Yunnanozoon'' somewhat resembles the Middle Cambrian ''Pikaia'' from the Burgess shale of British Columbia in Canada. Thirteen pairs of symmetrically ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Priapulida
Priapulida (priapulid worms, from Gr. πριάπος, ''priāpos'' 'Priapus' + Lat. ''-ul-'', diminutive), sometimes referred to as penis worms, is a phylum of unsegmented marine worms. The name of the phylum relates to the Greek god of fertility, because their general shape and their extensible spiny introvert (eversible) proboscis may resemble the shape of a human penis. They live in the mud and in comparatively shallow waters up to deep. Some species show a remarkable tolerance for hydrogen sulfide and anoxia. They can be quite abundant in some areas. In an Alaskan bay as many as 85 adult individuals of ''Priapulus caudatus'' per square meter has been recorded, while the density of its larvae can be as high as 58,000 per square meter. Together with Echiura and Sipuncula, they were once placed in the taxon Gephyrea, but consistent morphological and molecular evidence supports their belonging to Ecdysozoa, which also includes arthropods and nematodes. Fossil findings show th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ghost Knifefish
The ghost knifefishes are a family, Apteronotidae, of ray-finned fishes in the order Gymnotiformes. These fish are native to Panama and South America. They inhabit a wide range of freshwater habitats, but more than half the species in the family are found deep in rivers (typically deeper than ) where there is little or no light. The Apteronotidae should not be confused with the unrelated Notopteridae, which are also commonly called knifefishes. They are distinguished from other gymnotiform fishes by the presence of a caudal fin (all other families lack a caudal fin) as well as a fleshy dorsal organ represented by a longitudinal strip along the dorsal midline. They vary greatly in size, ranging from about in total length in the smallest species to in the largest. It has been claimed that ''Apteronotus magdalenensis'' is up to , but this is not supported by recent studies, which indicate that it does not surpass about . These nocturnal fish have small eyes. Also, sexual dimorphi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sternarchogiton Nattereri
''Sternarchogiton nattereri'' is a species of weakly electric knifefish in the family Apteronotidae. It is native to the Amazon River system and feeds on sponges. Unlike other members of the genus '' Sternarchogiton'', there is pronounced sexual dimorphism in ''S. nattereri'', with reproductively mature males developing strong external teeth on tips of their jaws. These males are so different from the females and juveniles that they were thought to be a different genus and species, the "tooth-lip knifefish" ''Oedemognathus exodon'', for over 40 years. Distribution and habitat ''S. nattereri'' is restricted to large river channels in the lowlands of the Amazon basin. Its habitat ranges from high-conductivity, sediment-rich whitewater rivers such as the Rio Solimões, to low-conductivity, sediment-poor blackwaters such as the Rio Negro. It is one of the most common gymnotiforms in Rio Solimões. Description ''S. nattereri'' has a laterally compressed, knife-shaped body. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dentary
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone of the skull (discounting the ossicles of the middle ear). It is connected to the temporal bones by the temporomandibular joints. The bone is formed in the fetus from a fusion of the left and right mandibular prominences, and the point where these sides join, the mandibular symphysis, is still visible as a faint ridge in the midline. Like other symphyses in the body, this is a midline articulation where the bones are joined by fibrocartilage, but this articulation fuses together in early childhood.Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, p. 59 The word "mandible" derives from the Latin word ''mandibula'', "jawbone" (literally "one used for chewing"), from '' mandere'' "to chew" and ''-bula'' (i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muraenidae
Moray eels, or Muraenidae (), are a family of eels whose members are found worldwide. There are approximately 200 species in 15 genera which are almost exclusively marine, but several species are regularly seen in brackish water, and a few are found in fresh water. The English name, from the early 17th century, derives from Portuguese , which itself derives from Latin , in turn from Greek , ; these are the Latin and Greek names of the Mediterranean moray. Anatomy The dorsal fin extends from just behind the head along the back and joins seamlessly with the caudal and anal fins. Most species lack pectoral and pelvic fins, adding to their serpentine appearance. Their eyes are rather small; morays rely mostly on their highly developed sense of smell, lying in wait to ambush prey. The body is generally patterned. In some species, the inside of the mouth is also patterned. Their jaws are wide, framing a protruding snout. Most possess large teeth used to tear flesh or grasp slipper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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