October 11, 2016 Leave a comment
December 8, 2014 Leave a comment
Some true flies can tolerate really filthy oxygen depleted water and use haemoglobin (red blood worm) or “snorkels” (rat tailed) to survive in these conditions.
The true flies are a very large and very diverse group. The Diptera is one of the largest orders with most of their families having an aquatic based larval stage. Their common physical traits are their elongated worm-like bodies, eyes and pro-legs. Their bodies can also be soft and naked; others have structural adaptations like being able to stick to solid surfaces (mosquitoes and black flies).
The true flies eat dead organic matter, and some breathe through their skin, others aren’t able to get the oxygen and have special structures to get atmospheric oxygen in the air. Mosquitoes and rat tailed maggots actually have “snorkels” that are pushed through the surface film to get the oxygen. True flies are found dwelling at the bottom, adhered to different substrates or free swimming; they can swim with strong and fast wriggling motions while others crawl using suckers, spines or pro-legs to drag themselves around.
The true flies have been thought of in a bad way because they are able to survive really poor conditions and multiply rapidly in those conditions. True flies are also sometimes the hosts of deadly diseases like malaria. However, this group serve a great ecological function of decomposing dead matter and they use up the “filth” to clean the system. They score a low 2 in the miniSASS because they are not sensitive to pollution, except for the net winged midge that is found only in the clean waters of mountain streams.
True flies undergo complete metamorphosis, passing through four life stages. The eggs are deposited in shallow fast-running water, either attached to a substrate or scattered on the surface of the water. After hatching the larvae are released, this is also an aquatic phase. The pupa form and this phase does not last long, depending on the temperature of the water and the conditions. The pupa are in a case or a hardened skin, pupa also count in the miniSASS. The case splits and the young adult emerges.