Skull of a generalized cichlid, showing a lateral view of the oral jaws (purple) and the pharyngeal jaws (blue)[1]
Dorsal view of the lower pharyngeal and oral jaws of a juvenile Malawi eyebiter showing the branchial (pharyngeal) arches and ceratobrachial elements (arch bones). The white asterisk indicates the toothed pharyngeal jaw. Scale bar represents 500 μm.[1]
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.[2][3]
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".[4][5] 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,[6] leading to three main four-bar linkage systems to generally describe the lateral and anterior expansion of the buccal cavity in fishes.[6][7] The most thorough overview of the different types of linkages in animals has been provided by M. Muller,[8] who also designed a new classification system, which is especially well suited for biological systems.
^ abFraser, G. J.; Hulsey, C. D.; Bloomquist, R. F.; Uyesugi, K.; Manley, N. R.; Streelman, J. T. (2009). "An ancient gene network is co-opted for teeth on old and new jaws". PLOS Biology. 7 (2): e1000031. doi:10.1371/journal.pbio.1000031. PMC 2637924. PMID 19215146.
^Mabuchi, K.; Miya, M.; Azuma, Y.; Nishida, M. (2007). "Independent evolution of the specialized pharyngeal jaw apparatus in cichlid and labrid fishes". BMC Evolutionary Biology. 7 (1): 10. doi:10.1186/1471-2148-7-10. PMC 1797158. PMID 17263894.
^Alfaro, M. E.; Brock, C. D.; Banbury, B. L.; Wainwright, P. C. (2009). "Does evolutionary innovation in pharyngeal jaws lead to rapid lineage diversification in labrid fishes?". BMC Evolutionary Biology. 9 (1): 255. doi:10.1186/1471-2148-9-255. PMC 2779191. PMID 19849854.
^Cite error: The named reference Gai2012 was invoked but never defined (see the help page).
^Cite error: The named reference Maisey2000 was invoked but never defined (see the help page).
^ abWestneat, Mark W. (September 1990). "Feeding mechanics of teleost fishes (Labridae; Perciformes): A test of four-bar linkage models". Journal of Morphology. 205 (3): 269–295. doi:10.1002/jmor.1052050304. PMID 29865760. S2CID 46933606.
^Olsen, Aaron M.; Camp, Ariel L.; Brainerd, Elizabeth L. (15 December 2017). "The opercular mouth-opening mechanism of largemouth bass functions as a 3D four-bar linkage with three degrees of freedom". Journal of Experimental Biology. 220 (24): 4612–4623. doi:10.1242/jeb.159079. PMID 29237766.
^Muller, M (29 May 1996). "A novel classification of planar four-bar linkages and its application to the mechanical analysis of animal systems". Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences. 351 (1340): 689–720. Bibcode:1996RSPTB.351..689M. doi:10.1098/rstb.1996.0065. PMID 8927640.
oppose vertically, comprising an upper jaw and a lower jaw and can bear numerous ordered teeth. Cartilaginous fishes grow multiple sets (polyphyodont) and...
(/ˌnæθoʊˈstɒmətə/; from Ancient Greek: γνάθος (gnathos) 'jaw' + στόμα (stoma) 'mouth') are the jawed vertebrates. Gnathostome diversity comprises roughly...
armoured fish known as ostracoderms, first appeared. Most jawless fish are now extinct; but the extant lampreys may approximate ancient pre-jawedfish. Lampreys...
numerous teeth. The vertebrate jaw probably originally evolved in the Silurian period and appeared in the Placoderm fish which further diversified in the...
response to their diet. Fish that ate hard-shelled prey had a robust jaw with molar-like teeth fit for crushing their durable prey. Fish that ate softer prey...
A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawedfishes is covered with these protective scales, which...
digits. Fish can be grouped into the more basal jawless fish and the more common jawedfish, the latter including all living cartilaginous and bony fish, as...
several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The details of this jaw anatomy vary between species...
(khóndros) 'cartilage', and ἰχθύς (ikhthús) 'fish') is a class of jawedfish that contains the cartilaginous fish or chondrichthyians, which all have skeletons...
in fish. The two most anterior of these arches are thought to have become the jaw itself (see hyomandibula) and the hyoid arch, which braces the jaw against...
cartilaginous fish in the order Chimaeriformes /kɪˈmɛrɪfɔːrmiːz/, known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last three...
fishjaw, gullet or gill, and the fish in turn becomes firmly tethered by the fishing line. Once the fish is hooked (often colloquially called "fish-on")...
teleosts and other bony fish lies mainly in their jaw bones; teleosts have a movable premaxilla and corresponding modifications in the jaw musculature which...
first shaped and then inscribed using a hafted shark tooth. Elasmobranch Fishjaw List of sharks "Shark teeth". Enax, Joachim (June 2012). "Structure, composition...
formed from the endoderm, as seen in jawless fish species, or those form by the ectoderm, as seen in jawedfish. However, recent studies on gill formation...
males. The wrasses have become a primary study species in fish-feeding biomechanics due to their jaw structures. The nasal and mandibular bones are connected...
Middle and Late stages. By the start of the Early Devonian 419 mya, jawedfishes had divided into four distinct clades: the placoderms and spiny sharks...
that are internally positioned instead of external as in the related jawedfishes. The name Cyclostomi means "round mouths". It was named by Joan Crockford-Beattie...
(not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front...
Exocoetidae are a family of marine ray-finned fish in the order Beloniformes, known colloquially as flying fish or flying cod. About 64 species are grouped...
normal mandibular teeth in the breakdown of food. Animal tooth development Fishjaw: The primary oral jaws open and close the mouth, and a second set of pharyngeal...
foraging and predation. When the ROV approached the fish, they exhibited burst swimming, still inverted. The jaw and stomach of the anglerfish can extend to allow...
Juvenile fishFish go through various life stages between fertilization and adulthood. The life of fish start as spawned eggs which hatch into immotile...
Common names of fish can refer to a single species; to an entire group of species, such as a genus or family; or to multiple unrelated species or groups...
upper jaw is acknowledged to increase the force exerted on the prey to be engulfed. Protrusible jaws via a mobile premaxilla can only be seen in fishes within...
Fish farming or pisciculture involves commercial breeding of fish, most often for food, in fish tanks or artificial enclosures such as fish ponds. It...
the pectoral fins. The first fish lacked jaws and used negative pressure to suck their food in through their mouths. The jaw in the bowfin is a result of...
They are the closest relatives of jawedfishes, who emerged from within them and they would survive if the jawedfish are included. Cephalaspidomorphi...
Fish vary greatly in size. The whale shark and basking shark exceed all other fish by a considerable margin in weight and length. Fish are a paraphyletic...
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