This study investigates how the presence of symbiotic crabs (Pinnixa chaetopterana or Polyonyx gibbesi) in the tubes of the polychaete Chaetopterus variopedatus affects the worms' pumping activity and growth rates under laboratory and field conditions. In the field, worms whose tubes are inhabited by Pinnixa beat their fan segments significantly more frequently than do worms hosting Polyonyx, b...

To assess whether closely related host species harbour similar symbiotic communities, we studied two polychaetes, Chaetopterus sp. (n = 11) and Chaetopterus cf. appendiculatus (n = 83) living in soft sediments of Nhatrang Bay (South China Sea, Vietnam). The former harboured the porcellanid crabs Polyonyx cf. heok and Polyonyx sp., the pinnotherid crab Tetrias sp. and the tergipedid nudibranch P...