I have long been fascinated by the words stygofauna and troglofauna and a recent holiday to South West Australia gives me the impetus to share with you these relatively unknown and unsung lifeforms.
First, a plug for the wonderful West where roads and roadsides are immaculate.
My case in point is Surfers Point Park at Margaret River with its limestone block walls and buildings, clear graffiti-free panels explaining the history and surfing breaks.
The whole area is built on limestone, which is eroded and dissolved by slightly-acidified rainwater to create the many stalagmite- and stalactite-filled caves that are tourist meccas.
The ancient Greeks wrote of troglodytes as a race of cave dwellers and modern parlance keeps the word for those who are reclusive, reactionary or out of date. However, the troglodytes of the animal world do live in the dark and can be found in groundwater systems and caves.
The stygofauna live in these dark waters and the troglofauna live above the water table of the cave. Typical troglofauna include species of spiders and other arachnids, millipedes, beetles, crickets, cockroaches and many other invertebrates.
Some species of invertebrate troglofauna are specially adapted to underground life, and are typically blind and pale with elongated appendages to help them navigate in complete darkness.
Within the past two decades, scientific research and biological surveys, often associated with surveys for the purpose of environmental impact assessment of mining and other projects, have greatly increased knowledge about both these water dwellers and those that live on the dry part of the underground.
A recent review estimated some 1460 species of troglofauna marking the western half of the Australian continent as a world hotspot for these inconspicuous but important components of the Earth's biodiversity.
These animals contribute to ecosystems via nutrient recycling and as indicators of groundwater health, and all states have legislation in place to protect these subterranean species from extinction.
Formal environmental impact assessment is likely to be required if a land-use proposal may cause significant change to a habitat containing subterranean fauna.