I dig this because, on verbal description, this sounds rather dull. X-rays of fishes. Great. But when you actually see the images you remember two very important facts: First, fishes have tons of little, teeny bones packed into a relatively small body; Second, fishes come in a wide variety of frequently crazy shapes. That all adds up to fish x-rays being way more interesting than you might initially guess.
This is a great find by Not Exactly Rocket Science's Ed Yong. A tourist and a couple of researchers from the California Academy of Sciences have documented an instance of Pacific-dwelling jawfish hiding from predators by blending into the stripes of well-known camouflage guru, the mimic octopus.
This relationship is probably a rare occurrence. The black-marble jawfish is found throughout the Pacific from Japan to Australia, while the mimic octopus only hangs around Indonesia and Malaysia. For most of its range, the jawfish has no octopuses to hide against. Instead, Ross and Rocha think that this particular fish is engaging in “opportunistic mimicry”, taking advantage of a rare chance to share in an octopus’s protection.