As we saw yesterday, octopuses have an amazing ability to
camouflage themselves. This is particularly remarkable when you consider that
any predator the octopus would be hiding from would have a completely different
vantage point. The octopus’s view of the sea floor is entirely
different from that of a fish hunting from above. If the target area is
littered with many colors and textures, as in a coral reef, the octopus has to
choose whether to mimic a specific item or to match the general appearance of
the background. Noam Josef and Nadav Shashar of Ben-Gurion University of the
Negev, and Piero Amodio and Graziano Fiorito of Stazione Zoologica Anton Dohm
tested some octopuses to see which way they would blend.
The researchers used eleven images of Octopus cyanea and O. vulgaris, taken in the wild by SCUBA divers. Because of the way the sampling
was done, the authors were confident that each image represented a different
specimen. However, as the octopuses were not tagged (and were indistinguishable
to human eyes), there is some chance that the same individual was photographed
twice. For each picture, the appearance of the mantle (body of the octopus) was
compared to that of the total background area and to specific objects within that field
of view.
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