Oligochaete worms (Branchiura)

Taxonomic group

Oligochaeta: Branchiura

Diagnostic features

Branchiura sowerbyi is an introduced oligochaete worm found in slow flowing streams and rivers. Like other oligochaetes they are visibly segmented, but unlike most oligochaetes they have finger-like gills towards the end of the body. They are relatively small and fragile, often breaking into segments when sampled.

[Branchiura]. Image: Stephen Moore Image — Branchiura. Image: Stephen Moore

[Branchiura]. Finger-like gills. Image: Stephen Moore Image — Branchiura. Finger-like gills. Image: Stephen Moore

Typical habitats

Like other oligochaetes they are most common in slow-flowing waters where they inhabit fine sediments.

Feeding

They are deposit feeders, collecting fine organic matter from bottom sediments.

Indicator value

Hard bottom: unassigned; general oligochaete value 1
Soft bottom: unassigned; general oligochaete value 3.8

The tolerance values (ranging from 0 to 10) give an indication of which are the sensitive taxa (values of 8 or more) and which are the tolerant taxa (values of 3 or less). For more information see: Indicator species

We have found Branchiura in farmland and urban soft bottom streams. This genus has not been assigned tolerance values but the oligochaete worms have low tolerance values of 1 (hard bottom sites) and 3.8 (soft bottom sites).