Fish jaw

rdf:langString Fish jaw

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rdf:langString Closeup of jaw

rdf:langString Skull of a generalized cichlid, showing a lateral view of the oral jaws and the pharyngeal jaws

rdf:langString Lower jawbone with conical teeth

rdf:langString Lower jawbone with molariform teeth

rdf:langString ---- 16px Slingjaw wrasse protruding its jaw – YouTube

rdf:langString ↑ Skull diagram of the huge predatory placoderm fish Dunkleosteus terrelli, which lived about 380–360 million years ago

rdf:langString The sling-jaw wrasse has the most extreme jaw protrusion of all fishes.

rdf:langString Dorsal view of the lower pharyngeal and oral jaws of a juvenile Malawi eyebiter showing the branchial arches and ceratobrachial elements . The white asterisk indicates the toothed pharyngeal jaw. Scale bar represents 500 μm.

rdf:langString Relative to its size the stoplight loosejaw has one of the widest gapes of any fish

rdf:langString Spindle diagram for the evolution of fish and other vertebrate classes. The earliest classes that developed jaws were the now extinct placoderms and the spiny sharks.

rdf:langString center

rdf:langString horizontal

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rdf:langString Vertebrate classes

rdf:langString Stoplight loosejaw

rdf:langString center

rdf:langString Fish evolution.png

rdf:langString FMIB 45458 Head of a Malacosteus, from the Andaman Sea, 650 fathoms; showing the enormous mouth and formidable dentition, and luminous.jpeg

rdf:langString Acanthodes BW.jpg

rdf:langString Dunkleosteus intermedius.jpg

rdf:langString Dunkleosteus skull steveoc.jpg

rdf:langString Epibulus insidiator jaw protrusion.jpg

rdf:langString LPJ Boulengerochromis microlepis.jpg

rdf:langString LPJ Ctenochromis horei.jpg

rdf:langString Malacosteus niger.jpg

rdf:langString Toothed Oral and Pharyngeal Jaws .tiff

rdf:langString 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 old one has fallen out. Jaws probably originated in the pharyngeal arches supporting the gills of jawless fish. The earliest jaws appeared in now extinct placoderms and spiny sharks during the Silurian, about 430 million years ago. The original selective advantage offered by the jaw was probably not related to feeding, but to increased respiration efficiency—the jaws were used in the buccal pump to pump water across the gills. The familiar use of jaws for feeding would then have developed as a secondary function before becoming the primary function in many vertebrates. All vertebrate jaws, including the human jaw, evolved from early fish jaws. The appearance of the early vertebrate jaw has been described as "perhaps the most profound and radical evolutionary step in the vertebrate history". Fish without jaws had more difficulty surviving than fish with jaws, and most jawless fish became extinct. Jaws use linkage mechanisms. These linkages can be especially common and complex in the head of bony fishes, such as wrasses, which have evolved many specialized feeding mechanisms. Especially advanced are the linkage mechanisms of jaw protrusion. For suction feeding a system of linked four-bar linkages is responsible for the coordinated opening of the mouth and the three-dimensional expansion of the buccal cavity. The four-bar linkage is also responsible for protrusion of the premaxilla, leading to three main four-bar linkage systems to generally describe the lateral and anterior expansion of the buccal cavity in fishes. The most thorough overview of the different types of linkages in animals has been provided by M. Muller, who also designed a new classification system, which is especially well suited for biological systems.