Miracidia, the larvae of the liver fluke (Fasciola hepatica), a parasitic flatworm. Miracidia are tiny ciliated organisms which hatch from liver fluke eggs. They infect certain species of freshwater snail, the liver fluke's intermediate host. They penetrate the snail's tissues, and after further development, free-swimming larvae called cercaria emerge. These form cysts on nearby vegetation and are ingested by a ruminant or by humans eating uncooked foods such as watercress. Flukes emerge from the cysts and migrate into the bile ducts, where they pass eggs into the faeces, which contaminate water, thus continuing the life cycle. Liver flukes cause fascioliasis, a liver disease with symptoms including digestive problems, fever, pain, anaemia and jaundice. Footage filmed at Ridgeway Research, Gloucestershire, United Kingdom.