Like a sort of crystal boats these water fleas are floating, backs down, just beneath the water surface. They are able to do this with a tow of special water resisting hairs on the margin of each half of the scale, which protrude and are laid upon the water surface. In that way they are hanging on the surface film and can slide with ease in horizontal directions by a few strokes of their antennae. Their leaflike legs (phyllopods) whirl a constant stream of surface water through the scale, together with nourishing particles which are always on the surface, and sieve those out. The ostracod Notodromas monacha has almost exactly the same habit. The water surface is a life habitat for many creatures of the ditch. I saw that Megafenestra is also able to swim lower in the water, and that it does this also on it's back.

This waterflea has been on this website for years under the name of a somewhat different species: Scapholoberis mucronata. Thanks to Ian Gardiner, who explained me (by e-mail) how it could not be that species.

A bit explanation of the picture above: we are looking mostly at the rear side of the waterfleas, the head with its single compound eye is well visible on the left individual. The dark objects in the scales are eggs, the crustaceans themselves are positioned above that, a bit like red "lobsters", each in it's own glass bowl.