Do Sharks Have Eyelids: Why, Types, How Many, Several Facts


There is a lot of curiosity surrounding sharks’ anatomy. In particular, people want to know more about their eyelids. Let’s explore this further.

Sharks, like human beings and other mammals, have eyelids. However, some shark species have three eyelids, which makes them different from humans. This third eyelid acts as a protector against potential abrasions and also keeps the shark’s eyes moist.

Image Credits: “Great White Shark” by Elias Levy is licensed under CC BY 2.0

There are a lot of questions asked about sharks and their eyelids. Let us together take a look at some of the most commonly asked questions. 

Do all sharks have eyelids?

One of the most fascinating aspects of sharks is their unique anatomy. Let us learn together whether sharks have eyelids.

Sharks have eyelids, just like human beings and all other mammals. From a cursory glance, it might look like sharks do not have eyelids. However, that’s not the truth. They have upper and lower eyelids that do not come together or close all the way since sharks do not need to blink the way humans do.

A strong, thin membrane covers the eyes of the shark and protects it from any sort of damage that may be caused during hunting, shark attacks, or navigation.

Why do sharks have eyelids?

Image Credits: Sharks Underwater by Pixabay

Have you wondered why sharks need eyelids? This is a common concern that often comes up during discussions. Allow us to tell you more in this regard.

Sharks have eyelids to keep their eyes safe from abrasion that might occur during hunting or shark attacks. In addition, eyelids can protect the shark’s eyes from any potential damage that might occur during an attack. Besides, eyelids keep their eyes moistened which, in turn, helps them see clearly.

The bottom line is that the eyelids are an important component of the shark’s anatomy as they can protect their eyes from any potential injury during an attack.

Sharks eyelids types

You’d be surprised to know that sharks have a unique set of eyelids, which slightly differs from humans. Let us learn more in this regard.

Sharks have three eyelid types. The upper and lower eyelids are similar to the eyelids found in humans and can come together to protect the shark from potential injuries. Other than that, sharks have a nictitating membrane, also known as their ‘third eyelid.’ This slides over their eyeballs for protection. 

We must mention here that not all sharks have a nictitating membrane. Therefore, the upper and lower eyelids have great importance for such sharks, as they become responsible for protecting the shark’s eyes from potential abrasions.

Are sharks the only fish with eyelids?

Generally speaking, most marine animals do not have eyelids like humans do. Let’s figure out if sharks are the only fish with eyelids.

Sharks are the only fish with eyelids. Fishes, in general, do not have eyelids as they have no use of them. Since fishes stay in water, their eyes are continually lubricated and protected. Sharks, on the other hand, have a nictitating membrane that goes over their eyeballs for protection.

Most sharks have two eyelids and some have a third eyelid, known as the nictitating membrane.

Humans blink their eyes to keep out dirt and moisturize them. But, can a shark blink its eyes? Let us find out.

Sharks, like fishes, cannot blink their eyes. However, since they have eyelids, they can definitely close their eyes, which comes in handy to protect themselves against potential attacks. Sharks do not need to blink as they live in water, and their eyes are continually cleaned by it. Besides, the water keeps their eyes moist.

As mentioned earlier, sharks can close their eyelids, but blinking is not a necessary function for them as their eyes remain lubricated in the water.

The fact that sharks do not blink may come across as extremely strange to us. But there’s science behind it. Let’s find out.

Sharks do not blink because they simply don’t need to. Humans blink to clean their eyes, prevent air particles from entering them, and keep them moistened. Now, since sharks are continually in water, they do not need to blink to either lubricate or clean their eyes. Besides, they aren’t exposed to any air particles.

It is worth mentioning here that sharks have a thin membrane (nictitating membrane) over their eyes that protects the eyes from abrasion.

Do sharks have eyebrows?

An interesting question people often ask with regards to sharks is whether they have eyebrows. Let’s find out.

Sharks do not have eyebrows, and neither do fishes. The reasoning behind it is that eyebrows typically exist to prevent water from dripping into the eyes of animals who live on land, humans included. However, since fishes and sharks live in water, they do not have any practical use of the eyebrows.

Most aquatic animals do not have eyebrows. So, you are unlikely to find eyebrows on invertebrates or even reptiles or amphibians.

Do sharks have a third eyelid?

Image Credits: “Great White Shark” by Elias Levy is licensed under CC BY 2.0

The concept of a third eyelid may seem very strange. Let us figure out what it is and whether sharks have a third eyelid.

Sharks have a third eyelid, this is called as the nictitating membrane. The purpose of this eyelid is to form a layer of protection over the eyeball and prevent the shark’s eyes from potential injuries or irritation. In addition, it helps keep the eyes lubricated. However, not all sharks have a nictitating membrane.

In cases where sharks do not have a third eyelid, the upper and lower eyelids work together to avoid any potential damage to the shark’s eyes.

Do sharks have clear eyelids?

One of the most frequently asked questions pertains to the color of the shark’s eyelids. Let’s figure out whether they have clear eyelids.

Sharks do not have clear eyelids unless they have a third eyelid. The color of the upper eyelids is usually the same as their snout. Even the lower eyelid has the same color as the rest of their skin. However, if the shark has a third eyelid, also known as nictitating membrane, then its color is transparent. 

Therefore, to answer the question, sharks have clear eyelids only in the case of the third one. Otherwise, their upper and lower eyelids have the same color as their skin.

Do sharks have good eyesight?

We have spoken at length about shark eyelids. But, are you curious to know more about their eyesight? Let’s find out more about their eyesight.

Sharks have excellent eyesight. In fact, their eyesight in water is considered to be ten times better than that of humans. A unique aspect of sharks’ eyesight is that they are able to see in both monocular and stereoscopic vision. As such, the vision quality is always superior, even with sub-par depth perception.

Of course, some sharks have better eyesight than others. There are some other sharks, like great white sharks, who have terrible eyesight and often confuse humans for their prey.

Which shark has the best eyesight?

Although most sharks have good eyesight in general, some shark varieties have incredible vision. Let’s check out who they are.

The hammerhead sharks have the best eyesight among the shark species. This is because they are equipped with a distinctive snout and unique, hammer-like head, which allows them to have a 360-degree vision. In addition to this, they have excellent depth perception, which is not found in many shark species.

The downside to their excellent vision is that sharks can see up to a distance of 45 to 50 feet. They also have blindspots located behind their head and before their snout. As such, it is common for sharks to mistake humans for seals. 

Do sharks close their eyes during hunting?

A commonly asked question is whether sharks close their eyes during hunting or when they bite. Let us find out.

Sharks close their eyes when they bite into their prey. This prevents the shark’s eyes from getting injured in case there is a counterattack by the prey. However, the eyes do not close all the way as the sharks still need to see what is happening. Besides, the transparent nictitating membrane also protects the eyes while allowing the sharks to see their surroundings.

It is worth mentioning here that some shark varieties like the whale shark or the great white shark don’t have eyelids. Therefore, they roll their eyes back into their heads to protect them against potential attacks.

Conclusion

It is safe to conclude that the unique anatomy of sharks makes them one of the most interesting marine animals. Shark eyelids greatly help them in navigating deep oceanic waters with ease and without sustaining any life-threatening injuries. It protects the shark’s eyes and helps keep them lubricated. Therefore, eyelids play a prominent role in retaining the vision of the shark and helping them see clearly.

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