Polychaete – Bristle Worms

The Polychaete are a class in the Phylum of the Annelida and are divided into 24 genera with more than 80 families. There are more than 10000 species of bristle worms described. They have a great variety of forms. Due to their morphological and molecular biology, there is considerable doubt that Polychaete is a descendant community. This means that the species can not possibly be traced back to a last common ancestor.


Apart from a few exceptions, Polychaete populate the sea. Here you can find them in all habitats. There are, for example, bristle worms which live pelagic as part of the zooplankton, some live on rocky reefs and others are found in sandy soils. They can be seen close to the shore to the deepest corners of the oceans.


Among the Polychaete there are mobile and sessile species. Through the settlement of different habitats also different ways of life result. Thus, some of them are hunters who are equipped with large eyes, that sometimes even have lenses. Others are, however, carrion and substrate eaters. Filterers are also found among the bristle worms.

Threat to Humans

Caution should be exercised when diving. The hard bristles of the Polychaete penetrate easily into the skin and cause burning pain and skin irritation. The cause of this is not yet known. In 2008, the natural compound Complanin was isolated from the species Eurythoe complanata. This has an inflammatory action. It is recommended to remove the bristles by means of adhesive tape and disinfect afterwards.

Interesting Facts about Bristle Worms

On an expedition to the Challenger Deep, the deepest point on the earth, on May 31 2009, the research robot Nereus found a species of the bristle worms.

Riftia pachyptila is a species in the family of the Polychaete, which refers to their food through symbiotic archaea (bacteria). Archaea gain their energy chemotroph from hydrogen sulphide. The whole occurs in the complete darkness of the deep sea, in the environment of hydrothermal springs.

The largest bristle worm, Eunice aphroditois, reaches a length of up to 3m.

Apart from the species Palola viridis, none Polychaete are used as food. Palola viridis chokes off its abdomen every 353 to 382 days, which carries the sexual organs. The abdomen then float on the surface in large numbers, which increases the chances of reproduction. The inhabitants of Samoa and the Fiji Islands, in particular, collect them for consumption.

Species of Polychaete on the Canaries