MUCUS PRODUCTION AND PHYSIOLOGICAL ENERGETICS IN PATELLA VULGATA L.

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Abstract
Most energy budgets for marine gastropods lack a measured mucus term. This is a major omission since mucus is widespread in molluscan physiological processes. In this paper we outline methods for estimating mucus production in the intertidal gastropod, Patella vulgata L. This species uses mucus primarily for adhesion and locomotion. Pedal mucus production rates were measured in aerial environments of 70% relative humidity (RH) and 100% RH and in seawater. Animals in 70% RH did not move, while those in 100% RH and seawater were mobile. Animals in 100% RH showed the highest mucus production rate. Those in seawater secreted about 75% of the mucus produced in 100% RH and those in 70% RH only about 40% of that produced in 100% RH. Significant logarithmic relationships between mucus production rate and whole dry weight of animal, and mucus production rate and shell length were found in all cases. The mucus term in the energy budget was calculated as 23% of ingestion both for individuals and for a specific population. This is much higher than the estimate of 4% of Wright & Hartnoll (1981). We have recalculated an energy budget for Patella vulgata to include the substantial mucus term. The recalculated budget is structurally different from the original budget. This suggests conclusions drawn from budgets not including a measured mucus term should be regarded with caution.