miracidium

biology

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Last updated

June 30, 2026

Quick Summary

A miracidium is the first larval stage of a digenetic trematode, a type of parasitic flatworm. This free-swimming, ciliated larva actively seeks out and penetrates a suitable snail, which serves as its intermediate host.12

Within the snail, the miracidium develops into further stages, including sporocysts and rediae, eventually producing numerous cercariae. These cercariae then exit the snail to find a definitive host, completing the complex life cycle of these parasites. The term "miracidial" refers to anything related to this specific larval stage.23

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flatworm
Development
The first larval stage, the miracidium, generally is free-swimming and penetrates a freshwater or marine snail, unless it has already been ingested by one. Within this intermediate host, the parasite passes through a series of further stages known as sporocysts, rediae, and cercariae. Through a complex process of asexual replication,…
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The first larval stage, the miracidium, generally is free-swimming and penetrates a freshwater or marine snail, unless it has already been ingested by one. Within this intermediate host, the parasite passes through a series of further stages known as sporocysts, rediae, and cercariae. Through a complex process of asexual replication,…
Read More