Feeding and territorial behavior of Paralvinella sulfincola, a polychaete worm at deep-sea hydrothermal vents of the Northeast Pacific Ocean

Behavioral adaptations to the severe nature and high faunal densities of hydrothermal vent habitats have received little attention from researchers. In this study, video and digital still imagery were analyzed to document the feeding and general behavior of the polychaete Paralvinella sulfincola at deep-sea vents on the Juan de Fuca ridge (North-East Pacific). This worm lives in mucous tubes on the actively growing portions of sulphide mineral chimneys and is considered to be the pioneering macrofaunal species in this habitat. We identified 6 recurrent behavior patterns, including antagonistic territoriality between neighboring conspecifics. The latter likely explains the regular spatial distribution of P. sulfincola populations on the substratum they colonize, and the observed confinement of feeding and exploration activities to a definable territory around the tube opening. Territory size, territorial overlap and density were significantly related to body weight, further supporting the importance of size and aggressive encounters in the maintenance of the worm's feeding area. During feeding, P. sulfincola uses its buccal tentacles to gather particles from the substratum using two different capture modes: seizing single macro-particles and aggregation of small particles.