About Daphnia pulex
Daphnia pulex, the common water flea, is a microcrustacean arthropod (typically 0.2-3.0 mm long) found ubiquitously in freshwater around the globe, predominately in small ponds and ephemeral pools. D. pulex live for around 10-30 days, but can live up to 100 days in the absence of predation. Their anatomy is easily studied, due to the see-through carapce which reveals the internal organs at work.
Daphnia pulex is sensitive to environmental changes and exhibits context-dependent responses (e.g. switching from clonal to sexual reproduction, or rapidly changing haemoglobin levels) that make it a sensible agent to assess the ecological impact of environmental fluctuations. Predation can induce a range of morphological changes in D. pulex. In response to kairomones (chemicals released by predatory insect larvae), D. pulex develop small protusions (neckteeth) that act as a defence mechanism. It can also change size to avoid either detection by larger vertebrate predators, or consumption by smaller invertebrate predators.
In addition to its usefulness in a variety of research areas (including ecology, toxicology, and physiology), in evolutionary terms Daphnia pulex is important as a representative of the sister group to the insects, and can highlight genes present in the pancrustacean common ancestor.
Picture credit: Dr Paul D.N. Hebert (University of Guelph)
Taxonomy ID 6669
Data source JGI
This species currently has no variation database. However you can process your own variants using the Variant Effect Predictor: