In their natural environment, organisms are constantly fighting against multiple invaders such as viruses, bacteria, fungi, or hel- minths thanks to one of the most remarkable evolutionary adaptation that is immunity. Aquatic molluscs are particularly exposed to tre- matode infections since the 6000 known trematode species use molluscs as first intermediate hosts to achieve the asexual multi- plication phase of their complex life-cycle. Recently, complementary approaches using the pond water snail Biomphalaria glabrata, (gastropoda) an intermediate host of the human blood fluke Schistosoma mansoni, have yielded a number of unexpected results such as the existence of regulatory processes involving orthologs of mammalian cytokines as well as immune priming processes. These results support the idea that snail innate immunity is much more complex than originally thought and may present particular adaptations against trematode infections.