Swimming Ability of Notonectidae (Hemiptera)

In an earlier paper, I (Gittelman 1974) studied adaptations of fore-leg size and hind-leg lever systems for prey capture and swimming. Presently, the ability of 4 species of Connecticut Notonecta to swim against a current is studied as a test of predictions generated by this earlier work. To study leg mechanics we will schematically represent a leg or leg segment (femur, tibia, and tarsus) as a simple lever with the fulcrum at the articulation between it and the structure on which it articulates. Force (Fm ) is applied at the muscle insertions at the proximal end and the lever arm is the distance (Rf) from the fulcrum to where the force is applied, the resultant force (Fr) is the force generated by the lever to do work (press against water while swimming) at any given distance (R 2 ) away from the fulcrum and is related to the muscular force as follows: