Dermal Denticles

© Trevor Sewell/Electron Microscope Unit, University of Cape Town

Shark skin is pretty amazing—it's actually covered in tiny, hard structures called "dermal denticles". These might sound complicated, but they're basically just small "teeth" that cover a shark's skin.

This is what makes a shark's skin feel rough, almost like sandpaper, if you were to touch it from head to tail.

These denticles are not just there for making the skin rough, though.

They play a big role in helping sharks swim fast. The shape and pattern of the denticles reduce the water's drag, which is the force that slows things down when they move through water.

Imagine trying to walk quickly in a swimming pool—that's drag. With less drag, thanks to their denticles, sharks can swim quickly and smoothly through the water.

Pretty cool, huh?