A class of annelid worms that includes the earthworms. They have simple setae projecting from each segment and a small head lacking sensory appendages.
- ‘Annelids with a clitellum (a swelling towards the head of the animal, where the gonads are located) are classified in the Clitellata, which is further divided into Hirudinea and Oligochaeta (including the earthworms).’
- ‘Stewart affectionately describes him as an elderly man - ‘a dabbler, a homebody’ - pottering about observing members of the taxonomic class Oligochaeta as they went about their business.’
- ‘In traditional classification schemes, the Annelida consists of the Polychaeta and the Clitellata (the latter including the Oligochaeta and Hirudinida).’
- ‘The phylum Annelida is traditionally divided into three classes: Oligochaeta, Hirudinida, and Polychaeta (marine annelids).’
Modern Latin (plural), from oligo- few + Greek khaitē long hair (taken to mean bristle), because they have fewer setae than polychaetes.