GROWTH AND REPRODUCTION OF THE MINUTE LAND SNAIL PUNCTUM PYGMAEUM (DRAPARNAUD)

Abstract

Reproductive characters and growth of Punctum pygmaeum were investigated under laboratory conditions. Eggs were laid singly at intervals of 2–8 days. Egg size averaged 0.41 by 0.50 mm. Due to a variable period of egg retention, newly deposited eggs contained differently developed embryos resulting in an incubation period varying from 1 to 34 days. Each snail on average laid 6.0 eggs (range 1–16 eggs) during its life. Egg production rate and hatching success in individuals kept in isolation were the same as in individuals kept in pairs. Hatchlings measured 0.49 mm in shell breadth. Snails grew throughout their life, but the growth rate declined significantly at a shell breadth of 1.3–1.4 mm, the point at which the onset of sexual maturity occurred. Comparison of reproductive characters of snails living in leaf litter revealed that very small-sized species produce few, but in relation to their shell size large eggs, which they oviposit singly.