Recently researchers documented Amazon River dolphins (Inia geoffrensis) performing a curious behavior: aerial urination. A male turns on its back at the water’s surface and ejects a stream of pee into the air—and almost 70 percent of the time, the team reported in Behavioural Processes, a nearby male “receiver” approaches this spontaneous fountain.

The researchers speculate that male dolphins might use aerial peeing to deliberately communicate their “social position or physical condition.”