Diversity of Fishes
Fish Skull Animation: Jaw Protrusion
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From an evolutionary standpoint, fishes were the first animals to develop bony jaws. Versatile jaws and multiple feeding strategies allowed fishes to fill, or radiate into, a diverse range of niches.
skull animation fig. 1
lateral view of skull with bubbles fig. 2 The feeding mechanism shown here (fig. 1) - jaw protrusion - allows a fish to envelope prey items by extending its reach, in one example (the sling-jawed wrasse), by up to 65% of the normal resting length of the head. Figure 1 illustrates the preparatory, expansion, and recovery phases in the opening, protrusion, and closing (respectively) of the jaw in a stylized bony fish's head.
Fierce suction develops as a result of jaw protrusion (fig. 2). As a result, mouth volume increases and water and prey are forced into the fish's now tube-like jaws. Bones recruited to protrusion include those of the upper and lower jaws (mandible, maxilla, premaxilla) and many bones of the skull itself (ethmoid, palatine, supsensorium). A fish's head is made up of over 30 moveable bony parts controlled by more than 50 muscles. Take your time comparing each of these features by manipulating figure 3. fish skull model
fig. 3
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