Water-flea
Guides
Anomopoda
water fleas
Anomopoda is a group of small aquatic crustaceans commonly known as water fleas, classified within Branchiopoda and Diplostraca. The group includes several families of ecological and scientific importance, with some species widely used as model organisms in evolutionary biology, ecology, and toxicology. Anomopods exhibit remarkable reproductive flexibility, alternating between parthenogenetic and sexual reproduction. They occupy diverse freshwater habitats across the globe and serve as critical components of aquatic food webs.
Ctenopoda
Ctenopoda is an order of small crustaceans within the superorder Diplostraca, comprising three families: Holopediidae, Pseudopenilidae, and Sididae. Members are commonly known as water fleas and are predominantly freshwater inhabitants, though the genus Penilia is marine. The order is characterized by specialized swimming antennae and a body plan that reflects functional separation between locomotion and feeding appendages. Ctenopoda species have been documented across diverse aquatic habitats including lakes, reservoirs, wetlands, and coastal marine systems, with some species introduced to areas outside their native ranges by human activity.
Daphnia
water fleas, water-fleas
Daphnia is a genus of small planktonic crustaceans (0.2–6.0 mm) in the order Anomopoda, commonly called water fleas due to their saltatory swimming style. The genus comprises over 200 species distributed across diverse freshwater habitats worldwide. Daphnia exhibits cyclical parthenogenesis, alternating between asexual and sexual reproduction, and serves as a keystone organism in freshwater food webs. Several species, particularly D. magna and D. pulex, are extensively used as model organisms in ecology, toxicology, and evolutionary biology research.
Eurycercus
Eurycercus is a genus of large-bodied cladoceran crustaceans (water fleas) and the sole genus of the monotypic family Eurycercidae. Species reach up to 6 mm in length, making them among the largest anomopods. The genus contains 16 described species distributed across four subgenera, with a primarily Holarctic distribution and some extensions into the Neotropics and Southern Hemisphere. Species occupy littoral zones of freshwater lakes and ponds, often associated with submerged vegetation.