Numbers
~70 spp. in 4 genera in our area, ~220 spp. in 5 genera worldwide
(1)(2)Identification
body convex dorsally, broadly oval or boat-shaped (with pointed posterior) and brownish or reddish-yellow with dark spots; hind coxae very long, flat, and broad, covering much of the ventral surface of the abdomen - but this feature is not visible in dorsal photos
Range
worldwide, more common in temperate regions
(1)Habitat
larvae and adults are aquatic, preferring standing water such as large ponds that have no shade and plentiful algae
Season
adults year-round, larvae: spring
Food
larvae feed entirely on algae, either the filamentous forms such as Spirogyra, or macroalgae such as Chara
adults feed on oligochaet worms, small crustaceans, hydrozoans, the eggs of midges, and algae
Life Cycle
overwinters as an adult in permanent standing water
Remarks
adults periodically come to the water surface for air; atmospheric oxygen is captured in bubbles and stored in three places - under the wings, at the tail, and under the large coxal plates - allowing the beetle to breathe underwater for long periods
adults swim slowly and clumsily by "shuffling" (moving their legs alternately, rather than in unison like predaceous diving beetles do)
