The squid has fascinated microbiologists for years because of its harmonious relationship with just one bacteria -- Vibrio fischeri. The bacteria does not express light when it is freely roaming in the ocean, but when housed in the squid's light organ (located in its underbelly) it will work with the animal to emit light according to how much moonlight and sunlight is visible above. In doing so, the squid will glow a light blue to mimic the light from above, eliminating its shadow on the seabed and rendering it invisible to predators potentially lurking below. The two live a happy coexistence: the bacteria getting sustenance from the squid, the squid getting camouflage from the bacteria.
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