Distribution and size of a stalked barnacle (Octolasmis muelleri) on the blue crab, Callinectes sapidus

The objective of this research was to redescribe the spatial distribution of Octolasmis muelleri on Callinectes sapidus in order to explore the relationship between the spatial distribution and the size of O. muelleri on C. sapidus. Size distributions of O. muelleri were also investigated in order to elucidate the mechanism of colonization by the cyprid larvae. The distribution of 1832 O. muelleri over the inside and outside surfaces and proximal, medial and distal regions of gills 1 to 8 of 17 C. sapidus was non-random and in agreement with previous studies. A weak relationship was found between the size of O. muelleri and their spatial arrangement on the gills of C. sapidus. The modest differences in the size of O. muelleri on different gills and in different gill regions could be a function of different growth rates in different gill regions or colonization patterns that would place early arrivals in selected regions and thus give them a head start and a longer period of growth. An extended period of cyprid settling that occupies from 25 to 100% of the intermolt period of the adult instars of C. sapidus was suggested by the size distribution patterns of O. muelleri.