Phylum Arthropoda
Class Insecta
Order Coleoptera
Family Psephenidae
Common Name Water Penny
Distinguishing Characteristics
  • Body flattened with thoracic and abdominal segments expanded so that legs and head are obscured from above
  • Six tiny legs that contain four segments are concealed underneath the body
  • Tarsal claw(s) can be found on the last leg segment
  • Head with antennae inserted close together between eyes constricting clypeus from frons
  • Gills found on the ventral side of the body
Additional Pictures



  • Video: Dorsal and ventral views of Psehpenidae with focus on moving and gill aeration
Additional Links



Merritt, R W., K W. Cummins, and M B. Berg. An Introduction to the Aquatic Insects of North America. Dubuque, Iowa: Kendall/Hunt Company, 2008