In a new study that appeared in the renowned journal Systematic Biology, scientists of Ghent University (Belgium), and the University of Basel (Switzerland) have examined the evolution of waterfleas using state-of-the-art tools. These small crustaceans of the class Branchiopoda are key zooplankton species in aquatic ecosystems worldwide. Daphnia is perhaps the best known waterflea, containing herbivorous species that are widely used model organisms in biology, yet there are also predatory lineages such as the glass waterflea (Leptodora).