The redia is a small (1-2 mm) germinal sac that lives within the tissues of the mollusc first intermediate host. They have a mouth and pharynx, the dark-staining sphere at the upper right, just above the escaping cercaria, and a short gut, which is not visible in this specimen. The redia feeds on host tissues and may cause extensive damage to the mollusc. Rediae may live as long as the mollusc they are infecting, continually producing cercariae. This redia is a daughter redia because it is producing cercariae. Two developed cercariae are in its posterior, and one developed cercaria is in the process of leaving the redia through the birth pore, which is located at the anterior end. There are some lighter-stained bodies within the redia as well. These are cercariae in earlier stages of development. This redia was produced by a mother redia, which is morphologically similar but instead of producing cercariae, it produces large numbers of daughter rediae.
The cercaria which is escaping the redia has a long, simple tail (compare with Schistosoma), a dark staining acetabulum, and an oral sucker surrounded by a spiny collar, just like the adult Echinostoma.