Tremarode (flukes)
Aspidogastrea
- least well known
- Usually Single host mollusk
- Secondary host (rare) fish turtles
Digenea
- largest and most well known
- -complex life cycle
- Final host vertebrate
- Digestive, respiratory circulatory
• Egg - shelled embryo
• Miracidium - free-swimming larva; hatches
out from its shell; discards its ciliated
epithelium; penetrates intermediate host
• Sporocyst - sac-like form; several embryos
develop asexually to become rediae
• Rediae - embryo; pharynx and gut
• Cercariae - develop within the redua;
emerges from the snail; possess tail for
swimming; considered as juveniles
• Metacercariae - infective stage (definitive
host); encysted stage
• Second Intermediate Host - usually bears
the encysted metacercaria