The skiff beetles are a small family (Hydroscaphidae) of water beetles, consisting of 13 species in three genera.
Skiff beetles are quite small as water-dwelling beetles go, ranging in length from 1-2 mm. Their color ranges from tan to brown, and the elytra are cut short, leaving several tapering tergites of the abdomen exposed. The antennae are short, as are the legs.
They are typically abundant in streams in their range, both adults and larvae living amongst and feeding on the filamentous algae that grows on rocks, especially those in the marginal shallows. They can tolerate a wide range of water temperatures, including both icy snow-fed streams and hot springs. Adults carry their air supply under the elytra, with the aid of setae on tergite III.
The single large eggs are laid on algae mats, and the larvae are entirely aquatic, breathing through gills extending from the spiracles.
Hydroscaphid species have been reported from every continent except Antarctica.