Divers have discovered new life forms including species of worm and snail in a deep, flooded underwater cave near Nelson.
The National Institute of Water and Atmospheric Research (NIWA) says Australian cave divers spent 13 days at the Pearse Resurgence cave in the Mt Arthur Range.
They performed 74 dives in water temperatures of 6.5 degrees in December and January.
Dr Graham Fenwick says a colourless 6- 8mm long species of amphipod, or crustacean, was found on rock faces.
It belongs to the poorly known genus Paraleptamphopus, one of two genera within the New Zealand endemic Family Paraleptamphopidae," Dr Fenwick says.
Originally described from Canterbury's deep alluvial aquifers, this family is represented by species inhabiting groundwater and marginally subterranean habitats throughout New Zealand.
A minute gastropod snail of about 1.5mm diameter and an oligochaete worm about 8mm long which are new to science were found in the cave system.
Dr Fenwick says the discoveries show that biodiversity exists even in dark, extreme environments.
There are 16 diveable caves in the world deeper than the Pearse Resurgence, but only 10 have been explored at depths greater than that explored in the Pearse of 194 metres.