Liver fluke. The anterior end of an adult liver fluke (Fasciola hepatica) showing the oral and ventral suckers. The liver fluke is a parasitic trematode (flatworm). It has a ventral sucker on its underside, and a powerful oral sucker at its anterior, which connects with its gut. Both suckers aid movement and attachment to the host. Liver flukes infect 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, feeding on blood and tissue. They mature and lay eggs which contaminate water via the host's faeces. The eggs hatch and infect certain freshwater pond snails from which larvae later emerge. The larvae form cysts on nearby vegetation, thus continuing the fluke's life cycle. Footage filmed at Ridgeway Research, Gloucestershire, United Kingdom.