Fauna

Paleontologists sometimes refer to a sequence of faunal stages, which is a series of rocks all containing similar fossils.

The deepest burrowers are the ghost shrimps (Thalassinidea), which go as deep as 3 metres (10 ft) into the sediment at the bottom of the ocean.

Studies in the deep sea define macrofauna as animals retained on a 0.3 mm sieve to account for the small size of many of the taxa.

Whether an organism passes through a 1 mm mesh also depends upon whether it is alive or dead at the time of sorting.

To qualify as microfauna, an organism must exhibit animal-like characteristics, as opposed to microflora, which are more plant-like.

Stygofauna is any fauna that lives in groundwater systems or aquifers, such as caves, fissures and vugs.

Stygofauna can live within freshwater aquifers and within the pore spaces of limestone, calcrete or laterite, whilst larger animals can be found in cave waters and wells.

Stygofaunal animals, like troglofauna, are divided into three groups based on their life history - stygophiles, stygoxenes, and stygobites.

Troglofauna adaptations and characteristics include a heightened sense of hearing, touch and smell.

[8] Loss of under-used senses is apparent in the lack of pigmentation as well as eyesight in most troglofauna.