Their sizes differ from several hundred microns to more than five millimetre for the larger species. They reproduce in summer mostly parthenogenetic, that is, the eggs develop without undergoing fertilization. These eggs can also be found in populations under stress, such as during the drying up of a pond. Daphnia feeds on bacteria, fine detritus and very small algae. But not all water fleas are peaceful herbivores.
Some species are voracious predators.
Go to the next page where you can see Polyphemus pediculus giving birth. Only some species inhabit marine waters. They differ considerably in appearance from their freshwater relatives. The following page shows some interesting stages in the development of Podon and Evadne Water fleas are beautiful creatures to observe through the microscope. Go to the following page to see them photographed in dark field illumination.