Answer:
Step-by-step explanation:
The scientific name of the sheep liver fluke is Fasciola hepatica. Its life cycle consists of several stages:
1. **Eggs:** The life cycle begins with the adult fluke laying eggs inside the liver of the host, which is usually a sheep or another mammal. These eggs are released into the host's liver and pass out of the body through the host's feces.
2. **Miracidium:** When the eggs reach water, they hatch into larvae called miracidia. These microscopic organisms are adapted to living in water and have cilia for swimming. They must find a suitable intermediate host, typically a specific species of freshwater snail.
3. **Sporocyst:** Once inside the snail host, the miracidium transforms into a sporocyst, a sac-like structure that produces rediae.
4. **Rediae:** Rediae are larval forms within the snail host. They develop from sporocysts and can produce cercariae.
5. **Cercariae:** Cercariae are free-swimming, fork-tailed larvae that are released from the snail. They swim in water and eventually encyst on aquatic vegetation as metacercariae.
6. **Metacercariae:** When a suitable host, such as a sheep, ingests contaminated vegetation, metacercariae excyst in the host's digestive tract. They penetrate the host's intestinal wall and migrate to the liver, where they mature into adult flukes. In the liver, they feed on blood and cause damage to the host's liver tissue.
7. **Adult Flukes:** The mature flukes in the liver reproduce, laying eggs, and continuing the life cycle.
This complex life cycle of Fasciola hepatica involves both vertebrate and invertebrate hosts, with different larval stages adapted to survive in water or inside the host organisms. The fluke's ability to infect and damage the liver of its host makes it a significant veterinary concern, especially in livestock farming.