Not only are the ambersnails prey, they are also hosts. Though not the preferred host species, ambersnails can be parasitized by the trematode Cotylurus flabelliformis, more commonly known as duck flukes. Ambersnails, along with other snails and slugs, play important roles in the life cycles of many parasites, including the duck fluke, which needs to be passed from one host species to another in order to grow and breed. In the case of duck flukes, there is actually a third host in the process (mollusks) that must also be infected in order for the fluke’s life cycle to be completed. At the end of that cycle, ducks pass the fluke eggs in their scat, at which point all a snail needs to do is haplessly wander near the scat to become infected and start the cycle over again. Though not known to occur in ambersnails, moose brainworms, which actually prefer to live in deer because such an infection is fatal to moose, have similar life cycles involving different gastropods.