Water Flea (Alona affinis), photo by Ian Gardiner
In introducing water fleas, Gordon says: "Cladocerans are small crustaceans belonging to the orders, Anomopoda, Ctenopoda, Onychopoda or Haplopoda. Commonly called water fleas, due to their small size and jerky swimming motion, cladocerans are extremely abundant in most freshwater habitats. There are a few estuarine species but this group has not been successful in the oceans. Some species are planktonic living in the open water of lakes, while others live on or near the bottom or on aquatic vegetation. Some species are found primarily in small ponds or saline lakes which lack fish predators."
Read the rest of Gordon's introduction to the Cladocerans of BC.