Category Archives: Aquatic Beetles

Macroinvertebrates of south Western Australia’s salt rivers 6

Hydrophilidae Berosus discolor

There are several species of water scavenger beetles that are able to tolerate extremes of salinity. The larvae obtain their oxygen through abdominal gills and crawl on the stream bottom feeding on small midge larvae and crustaceans. The adults have heads that bend downward (deflexed) and club shaped antennae tucked under their eyes that help to break the surface film of the water when replenishing their air supply. The hairs on their hind legs assist the beetles to swim. The adults eat plants and organic debris.

Macroinvertebrates of south Western Australia’s salt rivers 1

Dytiscidae Necterosoma penicillatus

Necterosoma penicillatus is a predatory diving beetle endemic to southern Australia. The adults are able to tolerate extremes of salinity and have been collected in salinities of 130 ppt (over 3 times saltier than the sea), however the larvae require lower salinities to survive. The larvae have long swimming hairs on their legs and feed on their prey by piercing then pumping into them digestive juices with their long mandibles. They then suck up the liquefied food. The adults have long fringes of hair on their hind legs which act as paddles. They feed on their prey by pulling them apart with their strong fore legs and mandibles.