Riffle beetles. Found primarily in streams, although sometimes found in lake margins, some species associated with submerged wood. Adults ovate to elongate; small size, 1-8 mm; coloration black or brown, sometimes with bright red or yellow spots; head may be retracted into pronotum; antennae either short with 8 segments, or filiform with 10-11 segments; 5 visible abdominal sternites; sides of 4th or 5th sternites may be modified to grasp the underside of the elytra.

Larvae found in same habitats as adults; body shape generally cylindrical or hemicylindrical; body size ranges from 3-16 mm; 5-segmented legs, single claws; abdomen 9-segmented; sternites with pleural sclerites or sutures; urogomphi absent; last abdominal segment at least slightly emarginate; retractile anal gills covered by an operculum with internal hooks.