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Lymnaea stagnalis is a freshwater pulmonate gastropod that has been maintained as an inbred selfing population for more than 10 years. The growth curves of both normal and trematode-infected animals are described. Selfing animals reach sexual maturity after 16 weeks, and live for about 40 weeks. Trematode infection results in increased growth and earlier sexual maturity after 12 weeks. Two subpopulations were observed: 'kastanea', which grows following the pattern of the uninfected animals, with a lifespan of about 60 weeks, and 'feiwo' animals that grow much faster and live for more than 72 weeks, reaching a length of more than 56 mm. Selfing animals lay egg clusters regularly, hatching after 13 - 17 days. A number of abnormalities were observed during the development: partially fertilized egg clusters, dead embryos, infected eggs, embryos without shells, empty eggs, or twins that fully mature and hatch.

Keywords: Lymnaea stagnalis Linnaeus 1758; Pulmonate gastropod; Selfing, Artificial habitat.