Earthworm  (Lumbricus terrestris)

The common earthworm is an abundant species, which has an important role in the aeration and fertilisation of soil (3). It is the largest British earthworm (5) and has a reddish-brown back, a yellowish underside and an often prominent orange-red 'saddle' region known as the 'clitellum', close to the reproductive organs. Although this earthworm has a cylindrical body, the tail region may become flattened (2). The body is segmented, and has visible rings known as annuli; each segment bears small hairs known as 'chaetae', which help the worm to move through the soil (3).