Snail survival was not significantly affected by the frequency of mechanical hemolymph collections (from 24 h to 96 h).

Under repeated collections, hemocyte density and viability was independent of the sampling frequency, except at 24 h.

Over two consecutive hemolymph collections, we recommend increasing time interval to higher than 48 h.

Hemocyte ultrastructures have revealed two peculiar organelles that deserve further researches.