Feeding behavior of Polinices duplicatus and resulting color changes of the shell''s callus

The purpose of this study was to investigate the relationship between the feeding behavior of Polinices duplicatus and resulting color changes of the shell's callus. A mean feeding rate of 0.81 clams per day with a maximum feeding rate of 1.21 clams per day was determined. Feeding rates expressed as percent of the snail dry weight were 8.9% per day at maximum and 4.8% per day on average. Weathering of dead Polinices shells resulted in brown calluses, while brown was never found in the calluses of living snails. This weathering process was much slower than changes in the callus due to diet, never occurring more rapidly than 60 days. A change from purple to white while feeding (11.1 days) was found to be approximately three days longer than the reverse change during starvation. Diameter of the borehole was significantly correlated with the size of the snail, and variability of the borehole diameter increased with increasing snail size. Polinices drilled the left valve of bivalve prey 60% of the time. Snails with aperture widths of 1.5 to 1.9 cm were cannibalized most frequently, and the proportion of purple calluses was not a strong indicator of the amount of cannibalism.