World’s biggest shark is found to have ‘armored eyes’ lined with nearly 3,000 TEETH that protect its vision because the species lacks eyelids

  • Using ultrasounds, a team found whale sharks have teeth lining their eyes
  • Nearly 3,000 teeth were found on each eye that protect its vision
  • The whale shark can also retract 50 percent of its eye into the socket 
  • These findings contradict previous ideas that it does not rely heavily on vision 

The world’s largest shark has thousands of teeth surrounding each of its eyes that act like armor.

Marine biologists from Japan discovered the dermal denticles lining the outer surface of the membrane and each has some 3,000 teeth around it.

Because whale sharks do not have eyelids, the rows of ‘oak leaf-like’ structures protect their eyes, which contradicts theories that this species does not rely heavily on its vision. 

Along with the dermal denticles, researchers also demonstrated that the whale shark has the ability to retract about 50 percent of its eyeball into the socket.

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The world’s largest shark has thousands of teeth surrounding each of its eyes that act like armor. The eyes are located on the side of the shark’s square-like head (picture A)

A team from Japan’s Okinawa Churashima Research Center examined both living and dead whale sharks from aquariums in Japan and the US.

Whale sharks are the largest of their kind, as they can grow as large as 59 feet long.

Although massive, they are harmless to humans and feed on plankton and some types of fish.

These sharks do not have eyelids and their eyes are positioned at the corner of their heads, which leaves them vulnerable – but that is where the dermal denticals come into play.


Marine biologist from Japan discovered the dermal denticles lining the outer surface of the membrane and each has some 3,000 teeth around it

When viewing the structures through a microscope, the researchers described them as being oak leaf like in shape

Sharks have dermal denticals all over the body that reduce friction in the water, allowing them to swim faster.

However, this is the first case these structures have been observed on a creature’s eyes. 

‘We aimed to describe, for the first time, the detailed kinematic and morphological features of whale shark eyes that are associated with eye protection,’ reads the study published in Plus One.

‘We did this by applying some recent techniques, such as underwater sonography and micro-computed tomography, to analyze both live and dead specimens, and to compare them with those of other elasmobranchs.’

The team conducted ultrasound experiments and recorded the eye movement of the living specimens to uncover the dermal denticals distributed on the surface of the eye, around the iris.

Using an object-counting option in a software, the data showed that there were about 2,900 teeth surrounding the eye.

When viewing the structures through a microscope, the researchers described them as being oak leaf like in shape.

The ‘covering of the eye surface with denticles in the whale shark is probably useful in reducing the risk of mechanical damage to the eye surface,’ concluded the researchers in the study.

Whale sharks are the largest of their kind, as they can grow as large as 59 feet long. Although massive, they are harmless to humans and feed on plankton and some types of fish

The ultrasound data also revealed that the sharks can retract their eyes about 3.3 centimeters, which is nearly 50 percent of the entire eye.

When retracted, white connective tissue forms over the eyeball and fills the empty part of the socket.

‘Longerterm eye retraction behavior was observed once in a captive specimen (female, 5 m in total length at the time) at the Georgia Aquarium, which kept its eyes retracted for approximately 10 days in June, 2006, immediately following its transport to Atlanta from Taiwan,’ reads the study.

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