JoC's picture

Lymnaea stagnalis

Observed: 4th April 2012 By: JoCJoC’s reputation in Invertebrates
Lymnaea stagnalis

These pond snails, Lymnaea stagnalis, are from a garden pond in Bracknell, Berkshire. Every year the tadpoles in this pond are seen grazing on the snails. I had assumed they were only grazing the algae, but it seems they remove some of the snails’ shells too. I have not noticed this in other ponds. Is this a common occurrence?

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dejayM's picture


A very interesting post Jp. No-one has answered your question and I cannot. But the damage seems very deep (nearly full depth?) and I suspect too deep for tadpole grazing. Yes, tadpoles have "...four lower rows of labial teeth are recognizable with a strong lens.." but they are evolved (I assume) to graze soft vegetation. I would expect tadpoles to graze the shells of snails in this way but not to need the additional calcium. There are references on the web regarding the need to add calcium to aquaria, specifically for snails , so could these snails be suffering from calcium deficiency as well?
Tadpoles could develop a 'taste' for snail-shell and I'd expect the snails in question to bear scars forever - I wonder if the process continues in the Bracknell pond.