Cercaria of Fasciola hepatica. The cercaria has suckers and a digestive tract similar to the adult stage, along with excretory, nervous, and endocrine systems. They leave the snail intermediate host actively, and use their tails to propel themselves through water towards vegetation where they encyst.
Miracidium of Fasciola hepatica. The miracidium hatch from the egg when exposed to the appropriate warm temperature, moisture, light, and salinity. Using cilia that cover its ectoderm, the miracidium will swim to find an appropriate host and bore its way into the aquatic snail, shedding its cilia and becoming a sporocyst as it enters.
Adult Fascioloides magna in situ from a partially dissected, infected deer liver at necropsy. Fascioloides magna may infect wild ruminants, cattle, sheep, and pigs. However, wild ruminants, especially white-tailed deer, are definitive hosts and maintain F. magna cycles in wild environments. Infections of F. magna in domestic animals do not become patent and the parasite is either completely encapsulated or migrate through liver parenchyma until the infected host dies or is euthanized.