By watching cockeyed Histioteuthis heteropsis squids glide and pirouette through over 150 undersea videos, biologists at Duke University and the Monterey Bay Aquarium Research Institute (MBARI) have gathered the first behavioral evidence that the squids’ lopsided eyes evolved to spot two very different sources of light available in the ocean’s “twilight zone.”
These observations, combined with visual simulations, indicate that the large eye is specifically adapted for gazing upwards, searching for shadows of fellow sea creatures against the rapidly fading sunlight, while the small eye is specifically adapted for gazing downwards, scanning deeper, darker water for flashes of bioluminescence.
Video footage courtesy of MBARI.
