POSSIBLE BENEFITS OF EGG CANNIBALISM IN THE LAND SNAIL ARIANTA-ARBUSTORUM (L)

Hatchlings consume unhatched sibling eggs as well as eggs from neighbouring batches. In a laboratory experiment, 20 newly hatched sibling snails from each of 24 egg batches were divided into 2 groups and fed either conspecific eggs or lettuce for 10 days. Hatchlings fed a cannibalistic diet experienced an increase in wet weight 2.6 times as high as those fed on lettuce. Diet did not affect hatchling survival, but it did influence future survival: 66.6% of the individuals initially fed on eggs attained adulthood compared to 38.0% of those fed on lettuce. Cannibalistic hatchlings tended to complete shell growth more rapidly and thus became mature earlier than non-cannibalistic ones, but the groups did not differ in adult shell size. -from Author