Do you think teeth are boring or gross? From the iron-laden teeth of Komodo dragons to the horns on unicorns of the sea, the animal kingdom is filled with marvelous dental adaptations that will have you thinking again.
Sharks are covered in toothlike scales called denticles
Colored micrograph of shark skin showing the complex three-dimensional structures of its denticles.
Gregory S. Paulson/Getty Images
On supporting science journalism
If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
Cartilaginous fishes such as sharks, rays, skates and chimaeras grow three-dimensional scales on the surface of their skin. Each toothlike scale has a pulp cavity containing blood vessels and nerves and is covered in a mineralized, enamel-like tissue called enameloid. These scales—very unlike bony fishes’ flat dinner-plate-like scales—are called denticles and have widely different shapes and features, not just across species but also in an individual fish. Denticles found on a shark’s nose might be flat and round, resembling the patched surface of a soccer ball. But elsewhere on the body the denticles might look like overlapping cupped hands with ridges and points.
These denticles can serve a variety of functions, such as decreasing drag while swimming and perhaps even increasing thrust directly, explains Purdue University biomechanist Dylan Wainwright. “We think they’re also functioning in some way as protection for sharks,” Wainwright continues. “They may protect from both big things like bites from other sharks [and] from small things like ectoparasites.” (Some fish have been observed rubbing against sharks’ rough skin to scrape off their own parasitic riders.)
We still don’t know where teeth come from
Two competing theories about the evolutionary origins of teeth have been…
Read the full article here
