Life cycle of Anisus vorticulus (Troschel, 1834) (Gastropoda: Pulmonata: Planorbidae) in the laboratory

Abstract

Laboratory culture of 2004–2007 provided the following data on the life cycle of Anisus vorticulus (Troschel). Snails hatched in May–June and kept in pairs usually started reproducing 42–114 days after hatching, at the shell width of 3.0–5.2 mm and 3.75–5.1 whorls. Some of them continued reproduction next spring. Snails hatched in July-August and kept in pairs produced their first cocoons next year. In the year of hatching the snails produced their last cocoons till October, next year – usually till August. During their lifetime snails kept in pairs produced a maximum of 122 cocoons with a total of 511 eggs (per snail), and the number of eggs per cocoon ranged from 0 to 9. Snails kept in isolation produced a maximum of 10 cocoons (most without eggs, the remaining ones with eggs devoid of oocytes). The life span was 68–776 days (mean 423).