Dero digitata (Mueller, 1773)  

D. digitata is one of the most common species of naidine oligochaetes. It is a round, segmented worm, ranging in size from 6 to 32 mm, and weighing around 0.06 mg. It is whitish in color, with color hues varying depending on the worm's diet and current stomachal contents. In the anterior part it has a head formed by four ventral chaete-bearing segments, plus a cone-shaped prostomium and small peristomium. It has no eyes. As in other member of the genus,  the caudal region (pygidium) is modified into a characteristic ciliated branchial pavillion (also known as branchial fossa), which in D. digitata is well developed, and comprises four pairs of gills.This worm secrete transparent mucous tubes adhered to the substrates they inhabit, and tend to be found aggregated in clumps.

Description