Hydrothermal vent octopuses of Vulcanoctopus hydrothermalis, feed on bathypelagic amphipods of Halice hesmonectes

Abstract

A feeding frenzy of 12 octopuses of Vulcanoctopus hydrothermalis was observed from the manned submersible ‘Alvin’ at Parigo, a 2620 m deep hydrothermal vent on the East Pacific Rise. The aggregated benthic octopuses at the active vent used their arms and webs to forage on bathypelagic amphipods, apparently targeting their attacks based on contact with the swarming amphipods. Individual octopuses wrapped their arms around the mantles of smaller octopuses, apparently in competition for prey. Although members of the prey species, Halice hesmonectes, are individually small (<5 mm long), the density of their swarms may make them attractive prey for the octopus. Inactive sulphide spires encircled part of this vent site; octopuses that climbed these spires had easy access to the dense prey swarms. The presence of the spires may uniquely enable this site to support simultaneous foraging by large numbers of octopuses.