As Weddell seals dive deeper and deeper under the sea ice, almost 2,000 feet deep, light conditions reach complete darkness. How do Weddell seals see under the sea ice to hunt for food?
This is due to a special structure in their eyes named the tapetum lucidum. Have you ever seen your pet dog or cat in a dim room and it seemed like their eyes were glowing? This glow is caused by their tapetum lucidum eye layer.
My doggie nephews and niece left to right Remington, Beckett, and Von.
Photo Credit: Kate Ward
Organisms’ see because the retina converts light signals and sends them to the brain. Some species, like the Weddell seal, dogs, cats and other nocturnal animals have the special tapetum lucidum layer, which works like a mirror in the back of the eye. This is important in low light environments because if light photons enter the eye and the photoreceptors in the retina missed them, they will hit the tapetum lucidum and reflect back to the retina, giving them a “second chance” to be converted into signals to the brain, to be seen. In a dog the tapetum lucidum is 15- 20 layers thick, in the Weddell seal it is almost double the thickness approximately 30 layers. This adaptation allows the Weddell seal to see in low light conditions below the sea ice.
Anatomy of eye containing tapetum lucidum
Photo Credit: Quora.com
Did you know? Weddell seals use their whiskers to help find prey in deep, dark waters. Continue following my journals to understand how.
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