This is a photo montage of some microscope pictures of a hind leg of a (deceased) Lesser Water boatman. From left to right: the thigh or femur with a row of little pegs (see also picture below), the tibia with a broad side platen and large pegs, and the long foot or tarsus, seamed with wide hair fringes. The hind leg resembles a paddle: the muscular femur would be the fist holding the paddle, the tibia the handle (which helps by being wide) and last the tarsus as the blade of the paddle. Because the Lesser Water boatsman's paddle does not come out of the water there is a trick on the back stroke: the hair fringes on the tarsus flip together, strongly diminishing the water resistance. On the picture the fringes have collapsed. The white mass near the tibia is a group of microscopic animals, possibly Opercularia articulata. These sessile creatures are totally adapted to live on water bugs, which in turn have an everlasting struggle to brush them off.
On the tibia is a small comb, at the end on the joint with the tarsus. Click for an enlargement. (±100kb) -seen it √
Corixa species, femur with pegs. The number differs per species.