In keeping with the theme of senses, today we’ll take a look at the shark’s eye.
A shark’s eye is as advanced as its hunting technique.
It consists of two duplex retinas: cones and rods. Cones enable you to see in the colour whereas rods help the eye to adjust to light and dark by dilating and contracting the pupils to allow more or less light in. This allows the shark to see up to 15 meters long.
The shark’s eye is made up of the normal elements like a human’s eyes such as the cornea, lens, retina, pupil and iris.
The retina has two areas: the day vision and the low-light vision. The retina allows the shark to see better in darker and murkier water – even the silhouette of wounded seals in murky water. I actually watched a documentary where sharks adapted to using the light of the houses and street lamps to watch the seal try to swim at night. They observe the shadow of the seal swimming in and out of the water in the False Bay area and that is how they hunt at night! They have keener night vision and actually see their prey better at night – with the help of the Ampullae of Lorenzini of course. This makes their eyes more sensitive to light changes and movement.
Alright. So let’s zoom in on the science-y bits… A shark has a laterally compressed large and spherical lens. This means their eye is squished and semi-circular. Behind the retina is the tapetum lucidum – a mirrored crystal layer that detects light for a second time if the light is not properly processed the first time.
Sharks cover their eyes when biting prey
Most sharks have a nictating membrane. This is a clear membrane that covers the eye to protect it when biting prey.
But Great White Sharks do not have a nictating membrane so when they hunt their eyes roll backwards into the socket for protection against any threats.
So, basically, Great Whites have zombie eyes, they roll back in their head! So this pun could not be cornea but eye’ll allow it. See what I did there? I was just doing it to break the eyes. But now I’m just making a spectacle of myself.
By Kylie Samuels
