The Haliplidae or crawling water beetles are a comparatively small group of inconspicuous, small water dwelling insects. They belong to the coleopterous suborder Adephaga but differ from all other groups of this taxon in several important characters. The strictly algophagous habit of haliplid larvae is a feature not found in any other taxon of the almost exclusively carnivorous Adephaga. The extremely enlarged hind coxal plates of adults are also a highly unusual feature of Haliplidae. They function as an accessory breathing air storage and physical lung.
Adults live among aquatic vegetation along the edges of ponds, lakes, creeks or streams.
They prefer a mixed diet of chironomid eggs, oligochaet worms, small crustaceans, hydrozoans and algae. The swimming abilities are rather poor. Middle and hind tibiae are not flattened but equiped with a fringe of swimming hairs. The legs move alternately in contrast to predacious diving water beetles or most whirligig beetles. The English name of the group refers to their habit of crawling along different water plants.