Skulls are usually sinister images and this case is no exception. This one reveals a microscopic lethal battle in water samples from reservoirs in inland Piauí State. They are Lecane rotifers infested with Myzocytiopsis zoophthora parasites, a species of zoosporic fungi–organisms whose flagellated spores look like animals in the way they move. The circles on the degraded bodies of the rotifers are oospores, the sexual structures of the fungi. The presence of the parasite influences the dynamic of populations, since the rotifers are food for a variety of aquatic invertebrates.
Image sent by biologist Ribamar Rocha, a professor at the Natural Sciences Center of the Federal University of Piauí