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Bythotrephes cederstroemii
Phylum Arthropoda
Subphylum Crustacea
Class Branchiopoda
Suborder Cladocera
Family Cercopagididae
Distinguishing Characteristics
  • Body and legs not covered with bivalve carapace
  • Brood chamber round
  • Caudal appendage (tail spine) is extremely long with multiple paired barbs
  • Body length ranges from 1.5 to 5 mm plus an additional 5-7 mm tail spine
  • Bythotrephes is invasive in North America and native to northern Europe and Asia. It was accidentally introduced into the USA Great Lakes in 1982 and has spread to many smaller lakes in the Great Lakes region
  • Bythotrephes is predatory feeding heavily on smaller zooplankton
  • The long barbed tail spine affords protection from fish predation, especially young of year fingerlings
Similar Species
  • Similar in general body form to Cercopagis pengoi, another invasive species introduced into the Great Lakes. Although the overall length is similar, the body of Cercopagis is much smaller and there is a conspicuous loop in its tail spine near the distal end.
Additional Notes
  • Also referred to as Bythotrephes longimanus Leydig 1860, which may be a preferred name