Oomycetes, also known as water molds, are pathogenic microorganisms that resemble fungi and are responsible for a group of diseases affecting several plant species. To reach and infect plants, the zoospores—i.e., self-propelled spores—of oomycetes swim to their target using two flagella, one opposite the other. In a recent study directed by a CNRS researcher, physicists and biologists worked together to precisely measure the movement of each flagellum while a zoospore follows a linear trajectory and when it is turning. They used these data to develop a theoretical model.