Small animals

Aquatic worms

Small oligochaetes (Aeolosoma, Chaetogaster, Nais)

Segmented worms with bundles of bristles. Small species are transparent enough to watch the gut and blood vessels.

Aeolosoma under the microscope, excerpt 2. Video: TheDIMONDK, CC BY-SA 4.0, via Wikimedia Commons.

What to look for

  • Clear segments with bundles of bristles (chaetae) along the sides.
  • Often chains of individuals budding off at the rear.
  • Aeolosoma has coloured oil drops in the skin; Chaetogaster has a large pharynx at the front.

Size in the field

Usually longer than the field at 100×.

Where to find it

Among plants and detritus; Chaetogaster often lives on snails.

Clips 3

0:25Aeolosoma under the microscope, excerpt 2Aquatic worms 0:25Aeolosoma under the microscope, excerpt 1Aquatic worms 0:26AeolosomaAquatic worms