Pedal mucus production by the Antarctic limpet Nacella concinna (Strebel, 1908)

Pedal mucus production rates were measured in the Antarctic limpet Nacella concinna (Strebel, 1908). Measurements were taken over 30-min and 24-h periods to allow the relative amounts of mucus produced on attachment to substrata and during normal locomotory phases to be calculated. Mucus produced while N. concinna was attaching accounted for 80% of the mucus produced in a 24-h period. Rates of production were also assessed in relation to shell length, foot area and tissue ash-free dry mass (AFDM). Twenty-four hour production rates for specimens ranging from 11.7 to 45.9 mm in length (21.0 to 85.2 mg tissue AFDM), ranged from 0.49 to 1.87 mg dry mass · day−1. On a foot area basis mucus production in a 24-h period ranged from 0.61 to 2.34 mg dry mass · cm−2 and was inversely related to animal size. Residuals analysis and multiple regression of mucus produced in a 30-min period against shell length, foot area and AFDM failed to show that any of these parameters accounted for a significantly larger proportion of the observed variation than either of the others. However, shell length, foot area and AFDM were all highly correlated with each other. Rates of production were also compared between specimens held in normal laboratory conditions and animals which had been starved for a 5-week period. Starvation reduced pedal mucus production to 61 % of normal levels. C,H,N analysis of the mucus indicated that it was 24.5% carbon, 4.2°, hydrogen and 5.4% nitrogen, on a dry mass basis with the remaining 66% being mainly accounted for by oxygen and ash. These values were used to calculate a proximate composition of 31.1% protein, 12.0% carbohydrate and 2.5% lipid, and energy contents on this basis were 10.93 kJ · g−1 dry mass and 23.3 kJ · g−1 AFDM. Comparing these data with previously published estimates of food consumption showed that mucus production accounted for around 12% of the energy intake, but that this fell to 2.5% if the mucus produced on attachment was removed from the calculation.

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