Growth, Age Determination and Longevity in the Giant African Snail <i>Archachatina marginata</i> (Swainson)

Abstract

Growth rates in terms of shell lengths were investigated in four subspecies of Archachatina marginata (Swainson) under culture conditions. Number of shell whorls, shell pigmentation and microsculpture were also studied to assess their usefulness in age determination. The snails displayed a sigmoid growth pattern, with growth slowing down after 8 months of life. In the first 8 months, the mean daily growth rates in the four subspecies showed a range of 0.21-0.25 mm/day, while between 8 - 12 months the range was 0.11-0.13 mm/day. Between 12-15 months the growth rate had considerably fallen to 0.02-0.06 mm/day. The observed differences in growth rates between the subspecies were however not significantly different (p>0.05) in the first 12 months of growth. In terms of maximum sizes attained after 21/2 years of growth, A. marginata eduardi reached a shell length of 88.7 mm which was distinctly smaller (P