FRANCIS, A.W.; Richard Stockton College, Pomona, NJ: Comparative Feeding Biomechanics of Four Pleuronectiform Fishes

Four pleuronectiform fishes, two sinistral and two dextral species, were measured for mechanical advantage of lower jaw depression and elevation between sides of the head. Paralichthys albigutta and P. lethostigma are sinistral flounders with relatively long jaws, a large gape, and long, conical teeth for the capture of piscivorous prey. Etropus microstomus and Pseudopleuronectes americanus are dextral flounders with short jaws and a small gape for the capture of invertebrate prey. The bilateral asymmetry of lever arms and mechanical advantage was greater in the two dextral species than the sinistral species. Measurements of mechanical advantage also indicate fast, but relatively weak lower jaw depression and elevation in the dextral flounders. Lower jaw depression and elevation in the two sinistral flounders are predicted to be slower, but stronger. The relationship between bilateral asymmetry, mechanical advantage, and diet are discussed. Biomechanical measurements from a small sample of the sinistral Psettodes erumei are also discussed.