The life-cycle and feeding of the African freshwater leech<i>Helobdella conifer</i>(Glossiphoniidae)

Abstract

The life-cycle, breeding and feeding of the freshwater leech Helobdella conifera were examined in the laboratory. The life-cycle is annual with the young brooded by the parent for the first two months after hatching. Sexual maturity is attained two months after leaving the parent when the first batch of eggs are produced and the young brooded. The number of broods ranges from one to four with the majority producing three. A few young leeches fed on the snail Helisoma duryi while still attached to the parent but the majority did not feed until 11 days after leaving the parent with 12–23 small (4.0–7.0 mm) snails consumed before producing their first batch of eggs. The life time consumption of small snails ranged from 26–60 with no correlation between the numbers of snails consumed and the numbers of broods or the numbers of progeny. Leeches only fed on small, live H. duryi and did not feed on large (10.0–13.0 mm) individuals although they fed as scavengers on dead large snails. A strong preference was exhibited by H. conifera for small H. duryi compared to small P. acuta with the most of the feeding occurring in the dark.