Daphnia pulex is the most common species of water flea. It has a cosmopolitan distribution: the species is found throughout the Americas, Europe and Australia. It is a model species, and was the first crustacean to have its genome sequenced. Daphnia pulex occurs in a wide range of aquatic habitats, although it is most closely associated with small, shaded pools. Daphnia are prey for a variety of both vertebrate and invertebrate predators. The role of predation on D. pulex population ecology extensively studied, and has been shown to be a major axis of variation in shaping population dynamics and landscape-level distribution.
photo credits: Paul Hebert