🦈
External Anatomy
Nictitating Membrane (Sharks)
Palpebra tertia
A translucent third eyelid found in some sharks that covers and protects the eye during feeding strikes.
Region: Head Externally visible Unique to: cartilaginous
📖 Overview
Sharks like the tiger shark and blue shark possess a nictitating membrane that sweeps across the eye during attack, protecting the vulnerable eye from struggling prey while the bite is delivered. White sharks lack a nictitating membrane and instead roll the entire eye backwards.
✨ Fun Fact
The nictitating membrane is one of the reliable ways to identify a shark strike sequence on underwater video - the eye closes an instant before the jaws close on prey.
🔗 Related External Structures