Sex could be determined for 609 specimens of C. galea and 115 specimens of C. caribaea. In C. galea, 74.4% were male. With 64.3%, the fraction of males in C. caribaea was lower (p = 0.030). Females were larger than males in both C. galea (χ2 = 133.9; p < 0.0001) and C. caribaea (F = 35.1; p < 0.0001). Both males and females were found on all but one host species (C. caribaea on Porites furcata Lamarck, 1816, on which only female specimens were found). Sex ratios within C. galea differed among snails associated with different host species (p = 0.0004; only including hosts with ≥ 5 specimens; Fig. 13a). After Bonferroni correction of p-values (n = 78) one pair remained significant: snails associated with Agaricia humilis Verrill, 1901 had a higher male to female ratio than snails associated with Colpophyllia natans (Houttuyn, 1772) (p = 0.032). Within C. caribaea, no variation in sex ratios between host species existed (p = 0.975; only including hosts with ≥ 5 specimens; Fig. 13b). Sex ratio of C. caribaea associated with alcyonaceans (66.0% male) and scleractinians (63.1% male) was similar as well (p = 0.845).
Within C. galea, mean length of females per host species correlated with the mean length of males (R2 = 0.707; p = 0.0002) (Fig. 14a). The same was observed in C. caribaea (R2 = 0.614; p = 0.011) (Fig. 14b).