6. Feb, 2016

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.

Sources:

http://www.fishbase.org/summary/6071

https://en.wikipedia.org/wiki/False_cleanerfish

Poulin, Robert; William L. Vickery (7 July 1995). "Cleaning Symbiosis as an Evolutionary Game: To Cheat or not to Cheat?". Journal of Theoretical Bi