White Shark Projects strive to teach both volunteers and our clients all about sharks. We regularly give our volunteers presentations on shark biology, behaviour, evolution and conservation. Sharks have been swimming around in the ocean for 450 million years. During this time they have developed abilities that have made them the ocean predators we see today.
Many people do not realise that sharks actually have eyelids, however, they do not need to blink like us humans as the surrounding water cleans their eyes. Just like us, the eyelids are also used to protect their eyes from damage. Although, a shark’s eyelid does not close all the way so they have developed extra eye protection.
One of the most interesting great white shark adaptations that we witness from our boat Shark Team, is their ability to roll their eyes back into their head when going for prey. This move is called an ocular rotation where the shark rolls their eyes completely back and an extremely tough piece of cartilage is exposed which shields the eyes. This is to protect the shark’s precious eyes from its prey inflicting injury during an attack. A great white’s prey includes animals such as fur seals which have very sharp claws and teeth and stingrays which are armed with barbs…. And these animals do fight back.
Other sharks such as the bronze whaler shark which we also see here in Gansbaai, have a nictitating membrane or third eyelid (also found in some reptiles and birds). This is a thin, tough membrane or inner eyelid that covers the eye and protects it from abrasion, mainly when feeding or encountering another shark.
The fact that sharks have developed these features may tell us that sight plays an important role for many shark species when focusing in on their food. However, the eye roll or nictitating membrane means that during the last moments when attacking their prey, the shark is basically blind and most likely relies on other senses such as electroreception and smell.
To learn more about these amazing creatures read our previous blogs.
For more information on White Shark Projects volunteer project visit our webpage or e-mail us at firstname.lastname@example.org