Shark Skin Secrets: How Bonnetheads Grow and Glow

Sharks have unique skin covered in tiny, tooth-like scales called denticles. These denticles help sharks swim faster and protect them during mating. Scientists wanted to see if these denticles change as sharks grow and if there are differences between male and female sharks. They studied 24 bonnethead sharks, both male and female, at different stages of life. They looked at the skin between the first and second dorsal fins using a powerful microscope. They measured different parts of the denticles, like their shape, size, and how they overlap. Scientists thought that younger sharks would have smaller denticles, and female sharks would have more overlapping denticles for extra protection during mating. They found that denticle shape, size, and overlap did change as sharks grew, supporting their first idea. However, they were surprised to find that sex did not make a big difference in denticle shape, except for the angle of the ridges. This means that as sharks grow, their denticles change to help them swim better and stay protected. Understanding these changes can teach us more about how sharks have evolved to survive and reproduce.