Sharks are large, usually gray saltwater fish. Unlike other creatures, they have a skeleton made of cartilage, not bones. Sharks also have sharp teeth. Compared to other fish, sharks have much tougher skin. This is due to their tough outer covering made of scales called "denticles". The only sharp part about these scales is the edges, so they are less likely to cut swimmers than the scales of other fish.
Sharkskin is composed of tiny, toothlike scales or dermal denticles that give it a rough texture. Sharkskin is made up of tiny, flat teeth similar to those found on a shark's jaw. These teeth are connected to each other and embedded in the skin. The rows of scales move in parallel to reduce turbulent water flow over the shark's body.
A few different types of sharks such as dogfish, catsharks, nurse sharks (pictured), and angel sharks have rows of small spines on their head or above their eyes that serve the same purpose of increasing friction between the shark's skin and water. These are called dermal denticles.
Nurse sharks have dermal denticles that are smooth instead of having sharp points like other sharks, which makes their skin feel sandpapery.
Sharkskin can be described as 'rough' because its exterior is unevenly textured by small scales similar to those on a shark's jaw. This is because the scales are made of a hard bone-like material called dentin and serve to protect them from wear and tear in addition to helping reduce drag while swimming.
In scientific terms, sharkskin can be described as being 'unevenly textured' by small scales that serve a protective purpose in addition to reducing drag.
The structure of the scales on the sharkskin surface is very much like sandpaper and can even cut through flesh if rubbed hard enough against it.
When scientists discuss the structure of sharkskin, they often compare the scales to sandpaper because they are rough and can be cut if rubbed against human skin. The color varies from species to species.
The color of sharkskin varies from species to species as does its shape and size. Some, like the angel sharks, are almost perfectly flat while others, such as the great white sharks, rise in a saw-tooth pattern.
The size and shape of each scale are different depending on the type of shark it came from. For instance, the scales on a great white shark are larger and more pointed while an angel sharks are almost perfectly flat.