To perform SEM imaging, we dehydrated the oocysts in series of graded ethanol solutions, starting with 50 % ethanol, and subsequent washes in 70 %, 80 %, 90 %, and 100 % ethanol. We then placed a suspension drop on the glass slide, and let it dry. We then coated the sample with a ∼5 nm layer of platinum using a Quorum Q150T-ES sputter coater. We imaged samples by a Carl Zeiss Merlin FESEM electron microscope using InLens imaging mode at magnifications in the range of 15,000 -50,000×.