Liver fluke. A juvenile liver fluke (Fasciola hepatica), newly emerged from its metacercarial cyst. This parasitic flatworm has an oral sucker at its anterior on the left, connecting with its gut, and a ventral sucker (central). It infects the livers of various mammals, including humans, causing a disease known as fascioliasis. Immature flukes emerge from cysts ingested with infected vegetation. They migrate into the bile ducts where they mature and lay eggs which contaminate water via the host's faeces. The eggs hatch and larvae infect certain freshwater pond snails from which further larvae later emerge. The larvae form metacercarial cysts on nearby vegetation, thus continuing the fluke's life cycle. Footage filmed at Ridgeway Research, Gloucestershire, United Kingdom.