Roundworm Dolicholaimus marioni
It is hard to see which end is which on a roundworm, as both ends of its thin body are pointed. The body is round in cross-section and has longitudinal muscles but no circular ones. This results in a characteristic way of moving in which the body is thrashed in a single plane forming C- or S-shapes in the process. This is a marine species, but roundworms also occur in vast numbers in the soil and fresh water.
- Phylum Nematoda
- Length Up to in (5 mm)
- Depth Intertidal
- Habitat Among algae in rock pools
- Distribution Shores of the northeastern Atlantic