When certain marine algae proliferate or "bloom," they can release toxins that kill fish—and even sicken beachgoers. Scientists believed the toxins primarily deterred fish that prey on the algae themselves. But a new University of Minnesota-led study says the widespread algae Karlodinium veneficum, which cause blooms called "brown tide," release toxins to paralyze another type of algae. In lab tests, K. veneficum algae lurked near their stunned prey, presumably waiting to feed.