The Skin That Bacteria Can't Grip

Bacteria cannot colonize a shark's body because the skin is a minefield of microscopic teeth. Instead of flat scales, sharks are covered in 'dermal denticles' that feel like sandpaper to the touch.

The shape and arrangement of these tiny teeth create a surface that is physically impossible for microbes to find a foothold on. The patterns disrupt the flow of water and create tiny vortices that essentially 'wash' the shark’s skin as it moves.

This is why you never see barnacles, algae, or thick slime on a shark. While whales and turtles are often covered in hitchhikers, the shark remains pristine. The texture is so effective that hospitals are now testing wall coatings modeled after shark skin to prevent the spread of superbugs.

This design also works to make the shark faster. By reducing drag, the denticles allow the animal to slice through the water with almost zero sound, making it the ocean's most silent predator.

Strangely, these skin-teeth are so similar to the teeth in a shark's mouth that they share the same enamel coating.