Greek: pogon = beard; phoros = bearer
were first described in 1900, but it was not until 60 years later that whole
specimens were obtained. The early descriptions did not include the
opisthosoma (see right). To date about 100 species have been described,
all coming from depths of 20 - 4000 m.
The worms range in length from 5 - 300
cm, and all are less than 3 cm in diameter. They live in a self-secreted
chitinous tube the length of their body, buried vertically in fine sediments.
Their body is divided into 4 regions:-
- the head with the tentacles
- the mesosoma
- the metasoma containing the gonads
- the opisthosoma armed with setae
They appear to have a mutualistic
association with chemoautotrophic bacteria which live in their body, and nutrients are absorbed through their hollow, anterior tentacles. About
half-way down their trunk they have two rings of chaetae which anchor to the
They may share a common ancestor in the Annelida, but there is no fossil record.