Deep Sea Squid Uses Mismatched Eyes to Detect Sunlight, Scan Ocean Floor

Researchers from Duke University have published a study on Monday in the journal Philosophical Transactions of the Royal Society B explaining why the cockeyed squid has two mismatched eyes and how it uses them to navigate its ecosystem as well as to look out for food and potential threats.

Scientifically known as Histioteuthis heteropsis, the cockeyed squid has long fascinated marine biologists for several decades and they have worked on end to discover the secrets to the deep creatures mismatched eyes and it uses them to serve its survival needs. Now the secret is out and scientists now know more about how the cockeyed squid uses its wonderful eyes.

Left eye looks overhead and right eye scans below

The left eye of this amazing creature grows faster and longer than its right eye. The left eye is exceptionally large and yellow and tube-shaped as well as double the size of the right eye, which is dark and small. But beyond this, the left eye is always looking up above the squid's horizon and the right eye appears to be fixated to scan the ocean floor below it, the Christian Science Monitor writes.

Marine scientists have now been able to figure out that the left eye is used to pick up rays of sunlight penetrating the waters and thereby catching the movement of any fish or other potential threats overhead, but the right eye seems to always be on the lookout for the bioluminescence given off by some deep see fish and other living organisms.

So the left larger eye is used for detecting sunlight and catching the shadowy movement of creatures overhead while the right small eye is used spot glowing fish in the darker recesses below. A professor of biology at Duke University and the lead author of the study, Sonke Johnsen, explained that the cockeyed squid developed these features to enable it survive in a complex ecosystem where alertness is better than size or strength.

Eyes are expensive to make and maintain

"Eyes are really expensive to make and maintain," lead study researcher Kate Thomas, a graduate student of biology at Duke University told Live Science. "You want eyes just big enough to do what you need to do, but you don't want to have any bigger eyes, because then you are just wasting resources."

To carry out their study, the scientists watched about 152 videos of cockeyed squid taken over a 30-year period at the Monterey Bay Aquarium Research Institute (MBARI) in California. They analyzed how the creature swims in an awkward upside-down position with its head down and tail up and came up with theories that drove the conclusions espoused in their publication.

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