Summary: Chapuis & Bshary (2010)

Signals alter the behaviour of receivers, thereby increasing the sender's fitness. When individuals interact cooperatively, signal strength may be linked to supply and demand (biological market theory). Hunger level in cleaner shrimps (Periclimenes longicarpus) is linked to advertisement of their services to client reef fish. To test more detailed predictions of biological market theory, Chapuis & Bshary (2010) investigated signalling by wild cleaner shrimps. Shrimps increased claw clapping when they were food deprived and were more likely to clean than non-clapping shrimp. Chapuis & Bshary (2010) however did not find evidence that signalling was target-specific to visiting client species, and shrimps signalled more frequently to predatory species. They conclude that signal conveys information about identity in order to avoid predation, rather than to attract choosy clients.