Eubrianacinae Jacobson, 1913 Eubriinae Lacordaire, 1857 Psepheninae Lacordaire, 1854 Psephenoidinae Hinton, 1939 Water-penny beetles are a family (the Psephenidae) of 273 species (in 35 genera) of aquatic beetles found on all continents except Antarctica, in both tropical and temperate areas.

[3] The presence of water-penny larvae in a stream can be used as a test for the quality of the water, as they are pollution-sensitive.

[4] They cannot live in habitats where rocks acquire a thick layer of algae, fungi, or inorganic sediment.

Water-pennies obtain oxygen through their membrane and through feathery gills located at the base of the abdomen.

They are typically found in riffles in streams with a moderate to fast current, clinging to the underside of logs or rocks.