The team aboard the Monterey Bay Aquarium Research Institute (MBARI) research vessel Doc Ricketts has a new gadget in their ocean-science arsenal: an array of blue LEDs. That might not sound like much, but when placed on a remotely operated vehicle (ROV), the lights allow MBARI to observe fluorescence in deep-sea animals like never before. The result is an unbelievable light show starring the alien life forms of the depths, including the strawberry squid (genus Histioteuthis).

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Because little light penetrates the deep sea, many of its inhabitants have evolved highly specialised eyes to detect the faintest changes in their surroundings. The tiny squid, which measures in at just 20 centimetres (8 inches), is one such creature. While one of its eyes is small and relatively unassuming, the other is extremely large, and fluoresces a brilliant green. 

The stunning colour is the result of light-absorbing pigments hidden within the squid's eye. But these pigments don't just sponge up any light: they're fine-tuned to absorb light in the blue spectrum (like that coming from MBARI's submersible). By keeping this gigantic eye on the sky, the strawberry squid can differentiate its prey from the blue-black background of the deep, where it would otherwise be invisible. 

This isn't the only tiny animal that relies on large, green eyes to survive fathoms below. Check out the incredible Pacific barreleye:

Evolution, we love you!

Top header image: MBARI/Screengrab from YouTube