Ghostly Denizens of the Pond - Chaoborus sp.

December's Mystery Organism was Chaoborus sp., the larval stage of the Phantom midge, a small fly often seen hovering in columns over ponds. This larva is a predator – the hooked mouth part is used to trap small planktonic crustaceans such as Daphnia and Diaptomus. Some great experiments and observational biology are possible using mixed cultures of Chaoborus and Daphnia you can collect in a local pond or lake.

Chaoborus is one of the few insects adapted for planktonic life. Gas filled floats at each end keep it horizontal in the water, ready to seize passing prey. Chaoborus lacks gills which normally (in other aquatic insects) take up dissolved oxygen from the water. Instead, dissolved oxygen passes directly through the thin cuticle, into the body fluids.

For a program that surveys many aspects of arthropod classification and functional biology, see our new production, Branches on the Tree of Life: Arthropods.