Biological Notes
        In general appearance, the capitellids resemble earthworms.   They burrow in sandy mud.   The eversible proboscis is used for burrowing.   Their thorax is stout, muscular and highly extensible.   When the thorax is extended, the abdominal segments with the long rows of hooks grip the substrate (Day 1967).

        Capitella lives in black mud and estuaries.   They are able to tolerate very low oxygen tensions.   Therefore, enormous numbers can be found in polluted areas such as harbour basins.  Capitella capitata are very useful organisms that can be used as indicator of organic pollution.   They dominate in Victoria Habour where is polluted from sewage and development activities.

Genera and Species Reported in Hong Kong

Capitella capitata
Heteromastus similis
Mediomastus californiensis
Notomastus latericeus
Octocapitella sp.
Paraleiocapitella sp.