Wednesday, October 01, 2008

Diplomats of the Reef?

Cleaner fish, or cleaner wrasse, are small blue fish that eat the parasites off larger fish. While these fish lessen their parasite load as well as a massage from the cleaner fish pectoral fins brushing against their sides, the cleaner fish receive a nice meal and is also not eaten. Interestingly, this lack of aggression extends to the cleaner fishes’ entire territory, or “cleaning stations,” where herbivores and carnivores peacefully coexist.

To test the hypothesis that the presence of cleaner fish kept the peace of at the cleaning stations, ecologist Karen Cheney of the University of Queensland and her team set up an experiment involving three aquaria containing a mix of herbivorous and carnivorous fish. In the first aquaria cleaner fish were added. In the second aquaria a third party fish that was neither predator nor prey was added. In the third aquarium no additional fish were added.

Cheney and her team found that in the second and third aquarium the herbivores were chased 7-10 times in 30 minutes with three prey species eaten. In the first aquarium, herbivores were only chased 2-3 times in 30 minutes and no prey fish were eaten. Researchers also found that the longer a predator was chased that less likely he was to chase prey after the cleaning ended. While cleaner fish clearly provide some kind of altering force in the reefs, the question remains, do the cleaner fish intentionally attempt to mediate between the predators and prey? To figure this out, the amount of time spent massaging predators would have to be compared when there is more or less prey present.

Posted by Amy Kawazoe (3)

Update 10/7/08:
Researchers believe that fish exist in many different modes: traveling mode, foraging mode, feeding mode, etc.. It is suggested that while the fish are in the cleaner fish territory they are in cleaning mode, explaining why the predators do not attack the prey. Some also suggest that the feeling of the cleaner fishes' pectoral fins against the sides of the larger fishes has a calming effect, perhaps giving another reason that there is little aggression shown in cleaner fish territory.


At 7:52 PM, Anonymous Anonymous said...

Wow, who would of thought something like this existed. I wonder how this technique of "keeping the peace" came to be in this species. Do you know of any other species that has a similar effect on the ecosystem? Both organisms involved seem to get something out of it, but what is that keeps them from eating the other fish that do not eat their parasites?

Katie Cole

At 6:54 PM, Blogger PWH said...

Who would have ever imagined that cleaner fish could play a role in fish attack behavior. I always thought of cleaner fish as just cleaners not peacemakers. I would love to know exactly what it is the the cleaner fish do that prevent the other fish from attacking. Is there any study on exactly how these cleaner fish keep the other fish at relative peace?

Chantal Gomes

At 7:41 PM, Anonymous Anonymous said...

How do they affect the fish around them? Perhaps the cleaner fish release some kind of chemical into the surrounding environment. If not, what is it about their presence that calms down the predator fish? I wonder if there are fish that are unaffected by the sedative stimuli elsewhere in the ocean ecosystem.

Jordan Grinstein

At 10:57 PM, Blogger PWH said...

It’s extraordinary that these cleaner fish are capable of keeping peace between predators and prey. Do you think the predators recognize the cleaner fish and somehow know not prey upon the cleaner fish and any surrounding species? Do you think it is a chemical the cleaner fish give off that calm the predators down? Nice article!

Carlos A. Varela

At 11:19 PM, Anonymous Anonymous said...

Neat. Do the cleaning wrasse clean both the prey and predator species, or only the larger predators? Why don't the predators attack the wrasse? Do you think it's because they "know" that they have a symbiotic relationship with them? I liked the idea that they release some sort of chemical into the water, as this might prevent the predators from attacking them. Maybe when the wrasse are cleaning the predators, it distracts them or the messaging calms them so they aren't thinking about eating while they are being cleaned. I somewhat doubt that this is what's going on, as finding food is important on the list of things to do for predators.

Rachel Carboni


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