 The copepod "Epischura baikalensis" is endemic to Lake Baikal and the dominating zooplankton species there, making up 80 to 90% of total biomass.It is estimated that the epischurans filter as much as a thousand cubic kilometers of water a year, or the lake's entire volume every twenty-three years.Among the most diverse invertebrate groups are the amphipod and ostracod crustaceans, freshwater snails, annelid worms and turbellarian worms