Chaetogaster

Chaetogaster is a genus belonging to the segmented worms (Annelida). It is classified in the family Naididae (subfamily Naidinae) in the order Oligochaeta. These are ca. 2–25 mm long transparent worms that are very common in fresh water and often form chains of individuals through asexual multiplication.

== Morphology == Externally, the animals correspond to the general building plan of the Naididae, however, in distinction from the other species, they bear setae (bristles) only on their ventral side, which is what gives them their name. The size of the worms, and of their setae too, is very variable even within single species.