In the world of humans, peeking at a neighbor while they bathe is not a commendable act, but for some fish species, spying on their neighbors to gather information is a matter of survival.
Fish living in coral reefs often find themselves plagued by skin parasites or suffer from thickened skin due to dead cells. To maintain a healthy and neat body, they rely on tiny “cleaners” to pick off parasites and flakes of dead skin.
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A cleaner fish is removing parasites from a customer fish. Photo: Bryan Harry |
Recent research has revealed that these “customer” fish choose their cleaners by observing them working on other fish.
The common cleaner fish, Labroides dimidiatus, which features black, blue, and yellow stripes, can choose between two options: either remove parasites from their customer’s skin or cheat and feast on the slime of that very customer—a much tastier option.
However, there are no penalties for the cheats. The customers, in this study represented by the fish species Scolopsis bilineatus, rarely eat the cleaner fish, even if they misbehave. This has long left researchers wondering why the number of cheats does not increase.
This is due to a process of “hiring” and “eavesdropping” by the customers to select the most reliable cleaners.
The researchers conducted an experiment wherein customer fish could observe two cleaners: one was diligently feeding on parasites from another customer, while the other merely drifted nearby.
Taking this information into account, the customer fish tended to choose the more industrious cleaner over the idle one.
The study was conducted by Dr. Alexandra Grutter and colleagues from the University of Queensland.
T. An
