Comparative morphometric traits differentiation and phenotypic correlations between Achatina achatina (Linne, 1758) and Achatina fulica (Bowdich, 1822) snails with four and five whorls

Four hundred (400) adult black-skinned snails, two hundred (200) each of the Achatina achatina and Achatina fulica with 4 and 5 whorls were used respectively for the study. Identification and sorting of the snails sourced from a reputable snail vendor in Ibadan into breeds was done using the appropriate profile and template. The body weights of Achatina achatina and Achatina fulica snails with 4 whorls ranged from 83.00 to 180.50 g (average 156.90 g) and from 30.60 to 85.20 g (average 49.70 g) respectively. That for Achatina achatina and Achatina fulica snails with 5 whorls ranged from 132.70 to 272.80 g (average 138.95 g) and from 50.60 to 119.30 g (average 59.58 g) respectively. Results obtained from the study showed that Achatina achatina snails with 4 and 5 whorls were genetically heavier and larger than Achatina fulica with 4 and 5 whorls. Results of phenotypic correlation coefficient among morphometric traits of the two breeds indicated negative, weak, low significant (P<0.05) and mostly non-significant (P>0.05) differences between body weight and most body components (morphometric traits) studied. The only positive, low non-significant (P>0.05) phenotypic correlation coefficient (rp) obtained was r = 0.420 between body weight and aperture width for Achatina fulica snails with 4 whorls. Whereas, for Achatina achatina snails with 5 whorls, positive, low significant (P<0.05) phenotypic correlation coefficients obtained was r = 0.529 between body weight and aperture width and r = 0.660 between spiral width and aperture width respectively. Achatina fulica snails recorded the only positive highly significant (P<0.01) phenotypic correlation coefficient of r = 0.602 between aperture width and shell width for the snails with 5 whorls. Breed type, age and size differences of snails used, body weight ranges, as well as number of whorls on snail shell have high effects of morphometric traits differentiation and phenotypic correlation coefficient estimates. Thus, the morphometric traits of the two breeds (Achatina achatina and Achatina fulica) of snails studied could be chosen to differentiate as well as characterize snails.