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Sample essay Sample Interactive - Week 2: Fish Skull Animation: Jaw Protrusion
This interactive was developed for the AMNH online course The Diversity of Fishes. The Diversity of Fishes is a part of Seminars on Science, a program of online graduate-level professional development courses for K-12 educators.

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Fish Skull Animation: Jaw Protrusion

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.

Figure 1: Front and Lateral jaw

The feeding mechanism shown here - 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. This animation illustrates the preparatory, expansion, and recovery phases in the opening, protrusion, and closing (respectively) of the jaw in a stylized bony fish's head.

Figure 2: Suction demonstrated

Fierce suction develops as a result of jaw protrusion. 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. (Note: Bubbles indicate direction of suction created by jaw protrusion.)

Figure 3: Relaxed vs. Expanded

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 this model. (Note: Stylized bony fish head. Left, frontal view; right, left lateral view.)

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