Daphnia pulex, commonly known as the waterflea, is the
first crustacean to have its genome sequenced. D. pulex has
a genome of approximately 200 Mb with 31,000 genes
http://wfleabase.org. Daphnid species are globally distributed
zooplankton, in the order Branchiopoda, suborder
Cladocera, and therDaphnids are commonly studied zooplankton
because of their importance to aquatic ecosystems,
ability to contend with environmental challenges,
amenability to culture, short life-cycle, and parthenogenic
reproduction. Furthermore, daphnids are commonly used
in several toxicity tests for multiple applications. Studies
on the Daphnia pulex genome and specifically the CYPs
may provide important insight on how genome and gene
expression alterations promote individual and population-
level fitness following environmental change.e are several daphnid species, includi