You ask, we answer! Welcome to Deep Sea Diary’s monthly Q&A – a great way to connect with Aquarium experts as you fish for more information about all things Ripley’s.
Q. I have heard that some sharks have a nictitating membrane. What exactly is this, and what is it used for?
A. While we have eyelids and eyelashes to protect our eyes from debris and injury, sharks lack these protective measures. Instead, some species of sharks have what is called a nictitating membrane. This thin, tough membrane, or inner eyelid, covers the eye to protect it from damage, especially prior to feeding event where the prey may inflict damage while defending itself. Not all sharks have a nictitating membrane. Sharks, like the great white shark and whale shark, lack a nictitating member and instead roll their pupils back in their heads for protection when feeding.
Q. How can you tell a male from a female shark?
A. Male sharks have paired, external reproductive organs called claspers, located on the underside of the shark. These claspers are actually modifications of the pelvic fins that function to deposit sperm into the female via grooves that lie in the upper side of the claspers. Females do not have claspers. Claspers are found on all male elasmobranchs (sharks, rays and sawfish).
Next time you’re in the Dangerous Lagoon Tunnel, be sure to look around and see if you can pick out the males from the females.