Most teleost fishes do not bite on their victims like sharks do [Alexander1983]. When a fish is about to eat it swims close to the victim and extends its protrusile jaw, thus creating a hollow space within the mouth. The pressure difference between the inside and the outside of the mouth produces a vacuum force that sucks into the mouth the victim and anything else in the nearby water. The predator closes its mouth, expels the water through the gills, and grinds the food with pharyngeal jaws [Wilson and Wilson1985]. We simulate this process by enabling the artificial fish to open and close its mouth kinematically. When it wants to suck in prey, it opens its mouth and, while the mouth is open, exerts vacuum forces on nearby fishes and other dynamic particles in the vicinity of the open mouth, drawing them in. The vacuum forces are added to external nodal forces in Eq. (). Fig. shows a predator fish ingesting prey fish.
Figure: A hungry predator ingesting prey.
|Xiaoyuan Tu||January 1996|