Earthworms are classified according to their behaviour and habitat:

• EPIGEIC - surface dwelling types that live at the surface in freshly decaying plant or animal matter.
• ENDOGEIC – live within the soil and ingest soil to extract nutrition from degraded organic matter.
• ANECIC – burrow deep in the soil and come to the surface at night to forage and deposit their castings.

There are about 3 500 earthworm species on the planet (some sources quote as many as 6000), of which 300 are represented in South Africa. Of these, only about 4 species are used commercially, mainly due to the fact that they ingest “rich” matter; are prolific breeders; can be kept in a contained environment and maintain a very high population density. None of the commercial earthworm species are able to live in soil, due to their need for high-nutrition content.

They are:
Eisenia fetida (Red Wrigglers)
Lumbricus rubellus (Tigers)
Perionyx excavatus (Blues) and
Eudrilus eugeniae (African Night Crawlers)