Cleaning Symbiosis

The banded coral shrimp is one of several “cleaners” on the coral reef. Typically, a male and female pair of banded coral shrimp establish a cleaning station where they wait for fish. To let a fish know that they are cleaners, they signal their intentions with ritualized body language that includes waving their barber pole–colored bodies. A fish interested in the shrimps’ services signals its willingness to be cleaned. These signals prevent cleaners from exposing themselves to fish that will eat them.

Hymenocera picta (The dancing shrimp) clean up starfish body
Hymenocera picta (The dancing shrimp) clean up starfish body

A busy cleaning station often has several fish lined up waiting for their turn. When a fish submits to cleaning, it may take unusual poses like headstands or exaggerated yawns so that the cleaners can do their work. The shrimp crawl all over the fish, removing parasites, mucus, and dead scales from their skin and mouth.
Cleaning is considered to be symbiotic behavior because the cleaner shrimps feed on the material that they remove from the fish. The fish in turn get “medical” treatment for parasites and skin problems. In studies where cleaners were removed from areas of the reef ecosystem, fish showed an increase in skin diseases.
The relationship clearly benefits both organisms. Shrimps are not the only reef organisms that clean fish. Some small fish species, like gobies and wrasses, perform the same type of work.