Living in the dark...

On Friday Pete went out to do some entomological recording at a spring near Woodston, which emerges from the limestone and then flows into the River Nene. The most exciting creature he captured was this blind shrimp Niphargus aquilex, which I photographed today. It wasn't easy at all - the whole animal is only a few millimetres long and rarely stays still!

The habitats from which the subterranean Crustacea have been recorded include; the interstitial water in the gravels of rivers and streams; underground aquifers in chalk and other strata; and pools and streams in caves and mines. It is believed that the true habitats of these species are the small channels of deep phreatic water in underground geological strata. Their presence in caves and mines is usually a result of the organisms being washed out of fissures in the rock, into streams and pools following heavy rain. This particular species is quite often found in springs.

Relatively little is known about the ecology of the hypogean Crustacea due to their cryptic habitat. Niphargus species are generally considered to be saprophagous, living on plant and animal detritus, much of which is washed into the subterranean habitat from the surface. However, some are predaceous on other invertebrates, including juvenile niphargids. Due to the scarcity of food in the underground habitat it is likely that they are opportunistic feeders, eating whatever they encounter. Silt and clay, with its associated bacteria and fungi are also thought to form part of the diet. Research has also highlighted the possibility that some subterranean aquatic organisms are capable of absorbing some of their nutrients directly from solution.