Black marble jawfish, Stalix histrio (Family: Opistognathidae) (red arrow) in association with the Indonesian mimic octopus, Thaumoctopus mimicus.
Image: Godehard Kopp (with permission).

Just when we think we have some sort of appreciation for the subtle beauty of evolution, another surprise comes along to remind us just how complex and multilayered the world truly is.

Discovered in 1998 off the coast of Sulawesi in Indonesia, the mimic octopus is the first species discovered that takes on the characteristics of multiple species. So far, we know that this octopus can copy the physical and behavioural characteristics of a number different species, many of them poisonous whilst others are merely dangerous, including sea snakes, lionfish, flatfish, brittle stars, giant crabs, sea shells, stingrays, jellyfish, sea anemones, and mantis shrimp. Furthermore, this octopus is so intelligent that it is able to decide which dangerous sea creature to impersonate that will act as the greatest deterrent to whatever predatory animal threatens it. For example, scientists observed that when the octopus was attacked by damselfishes, it mimicked the banded sea snake, a known predator of damselfishes.

But before I go further with this story, let me introduce you to the Indonesian mimic octopus, Thaumoctopus mimicus, a master of disguises:

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In this next video, we learn what scientists learned when they took a closer look at the evolution of this octopus to find out how its different abilities evolved into the animal that was recently discovered (doi:10.1111/j.1095-8312.2010.01484.x):

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As you saw in the above two videos, the mimic octopus is a brazen and audacious creature that got that way after it evolved a complex set of characters.

Next, let me introduce you to the black marble jawfish, Stalix histrio (Family: Opistognathidae). This small and shy fish spends most of its adult life close to a sand burrow, where it quickly retreats -- tail first -- as soon as it spies a predator. Such an easily-overlooked fish hardly seems a candidate for yet another master of disguises.

During a diving trip in Indonesia in July 2011, Godehard Kopp of the University of Göttingen in Germany, filmed a never-before-seen interaction between these two animals. In his video, we see the small and shy black marble jawfish closely following a brazen and audacious mimic octopus whilst it moves across the sandy bottom. The jawfish's markings are very similar to those of the octopus and as you'll see, it is quite difficult to see the fish as swims amongst the octopus's many arms.

Was the fish hiding from the photographer? Was it hiding from other fish? Maybe the fish was looking for leftovers from the octopus's latest meal? The octopus ignored its fishy companion, and the fish wasn't trying to escape, so it clearly wasn't a potential octopus meal.

Puzzled, and unable to identify the fish, Kopp sent his video to biologists Rich Ross and Luiz Rocha at the California Academy of Sciences (CAS). They identified the jawfish species and were fascinated by the peculiar association between the jawfish and the octopus. Since this association had never before been recorded, they published their observations (doi:10.1007/s00338-011-0855-y), along with the video. In that hot-off-the-presses paper, the authors propose that the jawfish is swimming with the octopus for protection, allowing it to venture away from its burrow to look for food -- a case of "opportunistic mimicry."

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In this video, it appears that there is some sort of relationship between the fish and the octopus. Certainly, it's a new behavior for the fish. Since the octopus can mimic so many other animals, and because the jawfish depends upon blending in with the octopus for its own safety, it appears that we are looking at yet another master of disguises.

"This is a unique case in the reefs not only because the model for the jawfish is a mimic itself, but also because this is the first case of a jawfish involved in mimicry," said Dr. Luiz Rocha, assistant curator of ichthyology at CAS, in a press release.

"Unfortunately, reefs in the Coral Triangle area of southeast Asia are rapidly declining mostly due to harmful human activities, and we may lose species involved in unique interactions like this even before we get to know them."

Sources:

Rocha, L., Ross, R., & Kopp, G. (2011). Opportunistic mimicry by a Jawfish. Coral Reefs doi:10.1007/s00338-011-0855-y

California Academy of Sciences press release.

Huffard, C., Saarman, N., Hamilton, H., & Simison, W. (2010). The evolution of conspicuous facultative mimicry in octopuses: an example of secondary adaptation? Biological Journal of the Linnean Society, 101 (1), 68-77 doi:10.1111/j.1095-8312.2010.01484.x [free PDF]

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