Looking at the Spiny Water Flea (Bythotrephes longimanus) may make you conclude it is an alien from outer space, how it is a member of the crustacean family Cercopagididae. The Spiny Water Flea is considered an invasive species capable of colonizing the lower level of the food chain and leaving a trail of destruction in an ecosystem. Though it has origins in Northern Europe and Asia, it has also colonized the Great Lakes region. They have a rapid growth rate and are recognized by a long abdominal spine bearing several barbs for protection. Juveniles show one pair of barbs on their spine while adults possess four pairs of barbs.