Body grips are not used like footholds.An animal swims or walks into a body gripper.This fires the trap onto the head or neck region of most animals.This kills tha animal.
As a sidenote,in most instances,bait is not hung over foothold traps.In most states,it is illegal to set a trap,within so many feet of a foothold.This is to keep our raptors from accidently being caught.
Tom