Just like reptiles, fish have scales on their bodies for protection against predators and hazards in the environment. Shark scales are particularly tough. Sharks are armored with teeth-like scales called dermal denticles. These overlapping, diamond-shaped ridges point toward the shark’s tail, reducing drag and boosting swimming speed. They work so well that Olympic swimsuit makers incorporated denticle designs in their fabrics.
Catfish and lamprey do not have scales. In addition to scales, fish have two layers of skin. The outer epidermis produces a slimy substance to ward off fungi and bacteria. The inner skin is tough and bony. Rings on a fish scale indicate its age.
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