| Through a complex process of asexual replication, each miracidium larva gives rise to dozens, or even hundreds, of cercariae. |
| Within the snail, the miracidium transforms into a sporocyst, which divides and eventually produces thousands of cercariae. |
| The larvae inside the snail host produce several thousands of cercariae. |
| Studies on cercariae from Physa gyrina Say, with descriptions of two new species. |
| Within this intermediate host, the parasite passes through a series of further stages known as sporocysts, rediae, and cercariae. |
| The different geotactic behaviour of the two species of cercariae brings them into the ecological range of their different second intermediate hosts. |
