Behavioural observations of the cephalopod Vulcanoctopus hydrothermalis

Introduction : The hydrothermal vent ecosystem is inhabited by poorly known species of deep-sea octopuses (Lutz & Voight, 1994). Vulcanoctopus hydrothermalis Gonzalez & Guerra, 1998, is the only described cephalopod from a hydrothermal vent (Gonzalez et al., 1998). Little is known about this small benthic octopus, up to 35 mm mantle length, with a muscular and semi-translucent body, lack of any type of chromatic elements in the skin and eye with no trace of an iris (Gonzalez et al., 1998). Its morphology was studied by Gonzalez et al. (in press) but there have been no behavioural studies of this species to date. Most observations of octopus behaviour in abyssal environments, mainly Cirroctopoda, have been described from videotape records (Boletzky et al., 1992; Villanueva et al., 1997; Vecchione & Young, 1997, among others). Live observations of animal behaviour at deep-sea hydrothermal vents are extremely difficult to carry out, mainly due to hostile environmental conditions such as pressure and darkness. The use of remotely operated vehicles (ROVs) or manned submersibles can impact the behaviour of the species being filmed (Spanier et al, 1994). In the abyssal zone, local conditions may change as a result of the spotlights, sounds, and turbulence of the submersible as well as the physical presence of a large object. However, video recordings, photographs, and direct observations using manned submersibles are the best means available to date for in situ studies of deep-sea animals behaviour (Hanlon & Messenger, 1996; Villanueva et al., 1997). The present paper reports the first observations on the behaviour of V. hydrothermalis based on video recordings.