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The upper jaw, or maxilla [12] [13] is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible (lower jaw), which is also a fusion of two halves at the mandibular symphysis. In bony fish, the maxilla is called the "upper maxilla," with the mandible being the "lower maxilla".
With their fusion of a beak-like tooth, there is a continuous series of arrow-shaped dental units that are surrounded by bone. [3] They can move from the base towards the edge as time goes on. Early on, the teeth begin to form a thick layer of enamel that protects the tooth from sustaining damage easily.
There is the presence of calcified strengthened cartilaginous jaws, calcified struts within the jaws and a lever 'nutcracker' system that amplifies the force of the jaw adductor muscles. The fusion of the palatoquadrate and mandibular symphysis, a restricted gape and asynchronous activation of the jaw adductors are key elements in the ...
Fish jaw: The primary oral jaws open and close the mouth, and a second set of pharyngeal jaws are positioned at the back of the throat. Ichthyology terms; Hallucigenia;
Most fish species with pharyngeal teeth do not have extendable pharyngeal jaws. A particularly notable exception is the highly mobile pharyngeal jaw of the moray eels.These are possibly a response to their inability to swallow as other fishes do by creating a negative pressure in the mouth, perhaps induced by their restricted environmental niche (burrows) or in the air in the intertidal zone. [10]
In all jawed fish (gnathostomes), the first arch pair (mandibular arches) develops into the jaw, the second gill arches (the hyoid arches) develop into the hyomandibular complex (which supports the back of the jaw and the front of the gill series), and the remaining posterior arches (simply called branchial arches) support the gills.
Tooth ankylosis refers to a fusion between a tooth and underlying bony support tissues. In some species, this is a normal process that occurs during the formation or maintenance of the dentition. [1] By contrast, in humans tooth ankylosis is pathological, whereby a fusion between alveolar bone and the cementum of a tooth occurs.
The lower jaw and maxilla are then pulled back to close the mouth, and the fish is able to grasp the prey. By contrast, mere closure of the jaws would risk pushing food out of the mouth. By contrast, mere closure of the jaws would risk pushing food out of the mouth.