The Physiology and Feeding Behaviour of Two Marine Scavenging Gastropods in Hong Kong: The Subtidal Babylonia Lutosa (Lamarck) and the Intertidal Nassarius Festivus (Powys)

Aspects of the physiology and feeding behaviour of the scavenging snails, Babylonia lutosa and Nassarius festivus have been studied and compared. N. festivus has a wider physiological tolerance than B. lutosa; upper lethal temperatures being 31.5°C and 28.5°C respectively and lower lethal salinities 15.5‰ and 11.5‰. N. festivus was also more resistant to desiccation. N. festivus is adapted to an intertidal environment that is more variable than the subtidal habitat of B. lutosa. The metabolic rate of adult N. festivus was two to three times higher than that of adult B. lutosa, the specific oxygen consumption rate of the former being 7.91±0.49×10−6 mol of O2.g−1 wet wt.hr−1. This correlates with estimates of consumption obtained for the two animals, B. lutosa eating, on average, 6.57% of its wet tissue weight per day, N. festivus 15.33%. Standardization of the data for 2 g animals of both species, however, reveals no significant difference in terms of oxygen consumption and thus the enhanced consumption by N. festivus simply reflects its smaller size. Both species are opportunistic feeders and can survive long periods of starvation (>100 days). The feeding strategies of the two are also different, N. festivus eating faster than B. lutosa, possibly because of the more ephemeral nature of carrion in the intertidal. Starvation affected the feeding behaviour of N. festivus more than B. lutosa and N. festivus was able to perceive carrion from greater relative distances than B. lutosa.