Wednesday, February 11, 2015

Hiding in Plain Sight

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Hiding in Plain Sight

It’s no mystery that there are numerous camouflaging methods through which prey hide themselves from their predators. Often, when we look hard enough, it can be observed that many of these tactics involve some kind of “blending” into the environment, such a tree frog settled amongst the green algae of a swamp.  Even zebras, with their seemingly bold black-and-white stripes are capable of blending in with the shadows of tall grass on the plains with these distinct patterns (in addition to providing a pretty neat cooling method as well). Staying out of the hunter's sight has often proven advantageous for the hunted, but what about tricking the predators who don’t rely solely on vision? Many species don’t just rely on visual camouflage, but rather on masking other sensory giveaways, such a scent. One such species that does so is the vibrantly colored Harlequin Filefish, native to the coral reefs found in the Indo-Pacific Oceans.
The Filefish consumes a highly specific diet of corral local only to its’ own habitat. Similar to the way sulfur compounds found in garlic can leave you smelling much like the pungent plant itself, the Filefish secrets an odor similar to the coral it consumes in its’ diet. In doing so, it cleverly blends into its’ habitat and remains undetected by its’ predators.


This hiding-in-plain-sight tactic is not a perfect science, however. An experiment was conducted where two different groups of Filefish were fed separate diets of two distinct species of coral. When placed in a tank with filled with both predators and one of the species of coral, only the fish in the group whose previous diet matched the coral found in the tank where able to remain undetected. Those belonging to the other group were as easy to seek out as any other undisguised type of prey. Fortunately for the Filefish, it’s bright coloring act as a secondary defence against predators, allowing it to blend in with the coral in its’ environment.


Very little is known about this particular form of chemical camouflage, and there is still much to be discovered. Some evidence, though not confirmed, suggests that the amino acids found in the fish’s mucus membranes responsible for most of their odor matches closely with their diet of coral. The case of the Harlequin Filefish is unique, in that it is the first non-insect species known to use chemicals to disguise its’ odor. Who knows what other interesting tactics organisms are using to avoiding being someone else’s lunch?

Posted by Hilary Mello (2)







6 comments:

  1. What an interesting study! Since humans are so reliant on their sight, we often forget that many organisms rely primarily on their other senses, and that something like this would be an evolutionary asset to an organism such as the Harlequin Filefish. Do you happen to have more information about the experiment done with the two separate species of coral? I'm interested in reading more about it.

    ~David Almanzar

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  2. Very cool. I never really thought that a fish could secrete a particular odor underwater, let alone for a specific purpose such as evading a predator. Does it say anywhere in the experiment exactly how this fish secretes an odor? Also does this fish rely solely on chemical camouflage for protection or does it use a combination of both chemical and visual camouflage?

    David Rains,

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  3. Fascinating, I haven't heard too much on chemical camouflage, especially for fish. You implied that insects use an odor changing mechanism similar to this fish, are those also used for camouflage or does it serve a different purpose in the insects?
    -Dan Staiculescu

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    Replies
    1. I personally only know of insects that use scent as a sort of defense, like stinkbugs. I always imagined their stench was used to repel the predator, but perhaps its used to hide them from scent-based predators as well?
      -Patrick O'Loughlin

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  4. It's really easy to forget the role that scent plays in aquatic environments, since we can't traditionally smell underwater. Yet, there's plenty of evidence that it's just as present as it is on land. This article provides one example, but plenty of ocean predators such as sharks use scent to hunt!
    -Patrick O'Loughlin

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  5. Cool post! Like the other commenters, I didn't realize that some organisms use scent to mask themselves from predators. Patrick commented an interesting fact as well - that scent plays a big role in aquatic environments! Do you think that the Harlequin Filefish's bright colors provide it with an incentive to evolutionary develop olfactory camouflage? Interesting read!

    -Michael Salhany

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