Egg size in squat lobsters (Galatheoidea): Constraint and freedom

Within the superfamily Galatheoidea, egg volumes of 52 species in the families Chirostylidae (Chirostylus, Eumunida, Uroptychus) and Galatheidae (Cervimunida, Galathea, Munida, Munidopsis, Pleuroncodes) were determined from measurements of eggs on females in museum collections. Correlations between egg size, body size, brood size, and depth of collection were examined for this data set. In general, significant, positive correlations between egg size and body size and between brood size and body size were observed. We found a strict dichotomy in egg size that corresponds to the generic classification of species examined but not to habitat. We noted a narrow range of egg sizes in species presumed to have planktotrophic larvae and a broad range of egg sizes in species presumed to have lecithotrophic larvae. These observations are discussed in the context of phylogenetic and biological constraints.