VARIABILITY OF EGG CANNIBALISM IN THE LAND SNAIL HELIX ASPERSA IN RELATION TO THE NUMBER OF EGGS AVAILABLE AND THE PRESENCE OF SOIL

Abstract

Egg cannibalism by hatchlings has been demonstrated in some pulmonate land snails; this behaviour is promoted by a high hatching asynchrony within the egg-batch. Under laboratory conditions, the percentage of new-born snails Helix aspersa having cannibalised unhatched eggs was not influenced by the soil factor: about 70% of them ingested one egg within their first four days of life whether soil was present or not. The propensity to egg cannibalism in hatchlings of H. aspersa increased with egg density. However, most of the new-born hatchlings consumed a single egg during the four days following hatching, and only exceptionally two. The consumption of one egg increased the snail¹s wet weight by 38.7% within four days. A weak ingestion of soil components also occurred, but it induced a growth that was three-times less than that due to the consumption of an egg. In addition, the survival of newly hatched snails maintained under non-dehydrating thermohygrometric conditions was high, even when they were submitted to four days¹ food-deprivation.