Liver fluke (Fasciola hepatica) is an endoparasite that occurs in the liver of some farm animals - Leaving Cert Agricultural Science - Question b - 2014

1. Members are flat (dorsoventrally compressed).
2. They possess bilateral symmetry and are acoelomate.

A diagram of an adult fluke should include the following labelled structures:

• Oral Sucker: Used for attachment to the host.
• Ventral Sucker: Assists in attachment and feeding.
• Testes: The reproductive organs that produce sperm.

The life cycle of Fasciola hepatica is as follows:

1. The adult liver fluke is attached to the bile duct of a primary host, typically a cow or sheep.
2. It lays fertilised eggs, which pass out of the host in the faeces.
3. In water, the eggs hatch into miracidia, which then penetrate a snail (the secondary host).
4. Inside the snail, the miracidia develop into cercariae, which are then released back into the water.
5. The cercariae attach to grass, forming cysts (metacercariae).
6. The primary host ingests these cysts while grazing, continuing the cycle.

A labelled diagram should include the primary and secondary hosts, as well as the stages of the fluke's lifecycle.