Cheating for survival; the false cleaner fish
Mimicry is one of the miracles of animal adaptation. It’s a form of camouflage used by various animal species to deceive a predator or a prey. Basically it can take two different forms, defensive or aggressive. An example of defensive mimicry is a harmless snake that mimics the colours of the deadly snake as protection against potential predators. So in defensive mimicry, the mimic generally benefits from being treated as harmful.
Aggressive mimicry is just the opposite. It’s a form of mimicry in which predators or parasites mimic a harmless model, allowing them to avoid being correctly identified by their prey or host. A example is the the false cleaner fish (Aspidontus Taeniatus) also called the sabretooth blenny. This little fellow mimics the bluestreak cleaner wrasse (Labroides dimidiatus) found on coral reefs in the Indian Ocean and Pacific Ocean. The real cleaner moves dead skin and parasites form the scales of its client fishes that line up in cleaning stations along the coral reefs. Not so with the mimic that occasionally may tear away portions of the scales or fins from the client. It not only looks like its model, but even cleverly mimics the cleaner's dance. The only difference are the more pointed lips with the enormous canines that sit in its lower jaw. Interestingly, a side effect of its mimicry could be also be defensive. Some predators like groupers that normally feed on various fish at a cleaner station, seem to spare the real cleaners, and therefore also their mimics.
The success of A Taeniatus is based on the fact that the mimic is rare compared to the genuinely symbiotic cleaner fish. When too many or too aggressive cleaners show op on cleaning stations they may spoil the foraging of the real cleaners. The clients will then become nervous and may even leave the cleaning station. This will screw things up, not only for the clients and the genuine cleaners but also for the false cleaners. For the same reason A. Taeniatus will attack only 20% of its ‘clients’, mostly juveniles who have not yet developed the skill to recognize the false intruders.
A. Taeniatus should not be with confused with a different looking false cleaner, the bluestriped fanged blenny (Plagiotremus rhinorhynchos). Of this species only juveniles mimic the bluestreak cleaner wrasse. Adults seem to behave differently and adopt an alternative color and striping pattern when they conceal themselves among fish shoals and then dart out to attack other fish or even a diver.
Poulin, Robert; William L. Vickery (7 July 1995). "Cleaning Symbiosis as an Evolutionary Game: To Cheat or not to Cheat?". Journal of Theoretical Bi