Choanoflagellates are a ubiquitous but enigmatic one-celled ocean organism that may give clues to the origin of multicellularity in animals. New research has turned up a surprising kink in the organism’s sex life: swarming and mating are triggered by a marine bacterium common in their environment. Researchers traced this response to a protein secreted by the bacteria. The choanos seem to be eavesdropping on bacteria to determine their life history.
