Television ads often use animals to sell things. How many animals, though, advertise for themselves?

Cleaner shrimp do—their bold stripes and antennae movements advertise their services to fish clients, which have their own way of requesting some crustacean TLC.

In a recent study, Eleanor Caves, a postdoctoral researcher at Duke University, and colleagues looked more closely at these signals between Pederson cleaner shrimp and their clients in the Caribbean Sea.

The team analyzed 199 encounters between shrimp and 10 fish species at a field station in Curaçao, the most common being spotted goatfish and ocean surgeonfish.

When a fish approaches a shrimp and holds its body very still—called posing—the shrimp then wave their antennae, signaling they’re willing to clean