The polychaete family Polynoidae (scale worms) is very diverse, and particularly well represented worldwide at deep-sea hydrothermal vents, cold seeps, and at sites of decomposing organic matter such as whale carcasses, sunken wood or even experimentally-enriched substrates. To date, more than 40 species (placed in 7 different subfamilies) are described that are only known from such chemosynthetically-driven ecosystems, and many more undoubtedly still await discovery or formal description. Most species are free-living in a wide range of habitats: from high-temperature hydrothermal 'chimney' walls to peripheral habitats with little or no influence from the reduced fluids. In contrast with those free-living species, polynoids of the genus Branchipolynoe Pettibone, 1984 (placed in the monogeneric subfamily Branchipolynoinae) occur exclusively in the mantle cavity of Bathymodiolus-like mytilid bivalves. As opposed to most other polynoids, Branchipolynoe species have well-developed gills in a dorsal position that most likely represent a favourable adaptation to oxygen-depleted environments. The true nature of this 'symbiotic' association is still unclear, but a few facts are known that suggest that worms are opportunistic commensals specially adapted to their hosts: Pettibone (1984) pointed out some morphological features seemingly connected with commensalism, and the protection such a life habit must provide against the numerous predators present at vents and seeps; Desbruyeres et al. (1985) found bits of mussel gills and pseudofaeces in the worms' gut contents; finally, infestation rates vary from up to 6 individuals per host to none, and mussels are known to occur without the worm, but not the contrary (pers. obs.). No report exists yet on a possible negative effect of the worm on its host.
|Original language||English (US)|
|Number of pages||4|
|Journal||Cahiers de Biologie Marine|
|State||Published - 1998|
ASJC Scopus subject areas
- Aquatic Science