Biological Features of a Buccinid Whelk (Gastropoda, Neogastropoda) at the Endeavour Ventfields of Juan De Fuca Ridge, Northeast Pacific

The newly described buccinid gastropod Buccinum thermophilum Harasewych & Kantor, 2001 is currently known only at hydrothermal vents of the Endeavour Segment of Juan de Fuca Ridge. Collected specimens from three vents show differences in shell features (colour, erosion, scarring) and size distributions. Such distinctions suggest that this buccinid forms resident, localised populations with limited inter-vent migration. Snail abundance in images taken every 31 hours varied markedly over time but showed no correlation with emerging fluid temperatures. Stomach contents indicate that this buccinid is an active predator and opportunistic scavenger with a broad diet. Substratum use did not differ significantly from availability but short-term, small aggregations occur, perhaps for mating and to exploit patchy prey. Majid crabs are active predators of these snails. Egg masses are similar to those described for other buccinids with over 200 egg-filled sacs in a mass; it was not possible to differentiate food eggs from embryos as all eggs underwent multiple divisions. Size-frequency distribution from the adults and the lack of advanced embryos in summer-collected egg masses provide some evidence of seasonality in reproduction.