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| Last Updated:07/01/2019

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This Squid Has Mismatched Eyes To Help It Survive In The Dark Ocean

Histioteuthis heteropsis, also known as "strawberry squid." Credit: Kate Thomas.


Researchers have found that the strawberry squid has evolved a lopsided set of eyes for seeing two very different sources of light available in the deep sea.


In the depths of the oceans, the water is murkier and freezing cold. As sunlight never reaches the ocean depths, these zones are literally pitch black. Yet animals somehow manage to survive these inhospitable conditions.
The deep sea dwelling creatures have evolved organ systems that are necessary for remaining alive in that particular environment like appendages, extraordinarily big eyes or eyes with the ability to produce bioluminescent light. The 'strawberry' squid has perhaps the weirdest feature of all.
The pinkish squid, also known as Histioteuthis heteropsis, has one huge, bulging, yellow eye and another normal-sized eye. This odd pair of eye is not without reason.


"You can't look at one and not wonder what's going on with them.” Kate Thomas, lead study researcher and biologist from Duke University said.
The squids' mismatched eyes have puzzled biologists since their discovery more than 100 years ago.
To gain insight into the function of these strange eyes, researchers looked through 30 years of videos collected by the Monterey Bay Aquarium Research Institute (MBARI) with documented 152 sightings of cock-eyed squid alongside nine sightings of its rarer close relative.
By watching these videos, researchers have found that the squids' lopsided eyes have evolved to spot two completely different sources of light available in the deep sea. The large eye is specifically adapted for looking upwards, searching for shadows of other sea creatures against the rapidly fading sunlight, while the small eye peers into the darkness below, seeking out bioluminescent signals.
"The deep sea is an amazing natural laboratory for eye design, because the kinds of eyes you need to see bioluminescence are different from the kinds of eyes you need to see the basic ambient light,” said co-author Sönke Johnsen. “In the case of the Histioteuthis, this cockeyed squid, they chose one eye for each.”
Histioteuthis heteropsis are found in the midst of the “twilight zone” – a region of ocean ranging from 200 to 1000 meters below the surface. Because very faint light comes down at this zone, these squids may have stumbled upon an ultimate solution for their survival: two eyes for two different purposes.


Source: 14U NEWS, Posted: Feb 13 2017, 12:57pm