Predatory behaviour and metabolic costs in the Antarctic muricid gastropod Trophon longstaffi

Aquarium-based observations of the feeding behaviour of the Antarctic muricid gastropod Trophon longstaffi over a 3-year period revealed that individuals were capable of feeding on both bivalve (Laternula elliptica and Yoldia eightsi) and brachiopod (Liothyrella uva) prey. Feeding activity was remarkably infrequent, with most individuals taking between 0.67 and 2.66 items per year, but two individuals ate nothing for 30 months and another ate nothing over the entire 36-month period. The time taken to attack and consume prey was extremely slow, with 20 days to complete an attack on the brachiopod Liothyrella uva and 29 days for the bivalve Laternula elliptica. Y. eightsi were mostly attacked by a wedging method. Most attacks were by drilling and the positioning of large, highly distinctive drillholes was broadly stereotypic. Metabolic rates for T. longstaffi ranged from 46.2 mug O-2 h(-1) for a 1.7-g tissue dry mass individual to 18-1 mug O-2 h(-1) for a 0.98-g tissue dry mass specimen. These rates are amongst the lowest so far reported for a gastropod mollusc but are within the range previously recorded for polar invertebrates. We suggest that T. longstaffi is well adapted for the low temperature, but highly seasonal, Antarctic conditions, with a low energy strategy and the ability to withstand highly extended periods of limited food availability.