Fine structure of the pedal muscle of the whelk Bullia rhodostoma reeve: Correlation with function

Abstract

1. 1. The fine structure of the pedal muscles of the whelk Bullia rhodostoma are described. Two types of muscle fibre, designated Type A and Type B, are found, the former in the propodium and the latter almost exclusively in the metapodium. 2. 2. Type A is a form of striated muscle capable of rapid shortening, which is essential during crawling and burrowing; hence its location in the anterior portion of the foot. 3. 3. Type B is more typical of molluscan smooth muscle, being able to maintain greater tensions, required to sustain turgidity of the foot during surfing.