Welcome back to another week on my Great White Shark blog. Last week I introduced the Great White Shark to you all. This week I will be focusing on one interesting anatomical feature that Great White Sharks possess, known as dermal denticles. Dermal denticles are flat rough v-shaped scales that line the bodies of Great White Sharks. The word dermal refers to the skin while denticles refer to the word teeth, which has given them the moniker of skin teeth. Dermal denticles act as a form of defense and hydrodynamics for the Great White shark. What do I mean by that? When people think of the Great White shark, some words that come to mind might include, strong, fast, predatory, ect. Dermal denticles are present on the shark as a form of defense and protection. Even rubbing against the denticles can cause tears in the skin. “The dentine layer of dermal denticles is composed of a hard, crystalline mineral called apatite, embedded in a soft protein, our old friend collagen. Due to their microstructure, dermal denticles are about as hard as granite and as strong as steel.” ( Center for Shark Research). In regards to hydrostatics, dermal denticles help in reducing the amount of drag that Great White Sharks might experience when swimming. They also help with canceling noise so that the shark can be stealthy when hunting its prey. In fact, dermal denticles functions are so impressive swimwear companies have taken to imitating the patterns for professional swimmers and divers. So I know what you are thinking, “What exactly is so unique about a defense mechanism such as this? Yes, it is impressive, but other animals have defense mechanisms as well.”
Well, dermal denticles are regenerative. In fact, all Great White Shark teeth are regenerative. Scientists have now discovered that the way that the dermal denticles regenerate is not random they couldn’t be. The teeth in sharks mouths are controlled by several genes that allow their regenerative properties. Scientists have found that dermal denticles also have genes that control their regenerative properties. Though they are both teeth, dermal denticles and mouth teeth are not the same regenerative wise. In fact, dermal denticles share a more similar regenerative pattern to chick feathers than to teeth regeneration. Their patterns during regeneration are also not random. Scientists have found that dermal denticles are formed by molecular signals that later on form the patterns on the Great White shark.
Though dermal denticles are a unique feature in sharks and some rays, researchers have found that the genes that make and pattern all vertebrate skin appendages, like feathers and hair share a common ancestry with those of dermal denticles. In fact researchers now dermal denticles, skin teeth, evolved first before oral teeth. They were first there as a form of protection but then evolved to a form for acquiring food. The core genes that make a pattern all vertebrate skin appendages, from denticles to feathers and hair, share a common ancestry.
I hope this blog post taught you something new about Great White Sharks. I hope you enjoyed the topic, and see you again on my next post.
Embedded below is a video on shark denticles. Enjoy.
The image below is of dermal denticles that line the shark’s head.