A Blue View: Up Close with Shark Teeth

If there’s one thing sharks are known for, it’s their teeth. Unfortunately, there are a few common misconceptions associated with those choppers—like the belief that most shark teeth resemble those of a great white.

Published May 31, 2016

In reality, shark teeth can vary drastically by species. Some bottom-dwelling sharks, for example, have flat teeth, which they use to crush hard-shelled prey.

To brush up on our collective shark-tooth knowledge, we’ve compiled a few fast facts for your personal consumption.

1. Sharks chomp on their own choppers. While in the womb, baby great whites swallow their own teeth. Experts hypothesize that it may be a source of calcium and other minerals.

2. New teeth arrive in no time. When a shark loses a tooth, a new one rotates forward replacing it within 24 to 48 hours.

Blacktip Reef Shark

3. The tooth fairy could never keep up. Some sharks can lose 30,000-plus teeth in a lifetime!

4. The teeth are all that remain. Sharks are cartilaginous fish, but their teeth are made of dentin—a hard, calcified tissue that doesn't easily decompose. When they die, the cartilage dissolves leaving the teeth behind.

National Aquarium – Sand Tiger Shark

5. There’s a “shark tooth capital of the world.” It’s Venice, Florida—according to Venice, Florida.

6. The Megalodon packed a mouthful. This ancient shark was alive approximately 15.9 to 2.6 million years ago and had some massive teeth that measured more than 7 inches long.

7. Shark teeth were once thought to be an antidote for poison. Way back in the Middle Ages, fossilized shark teeth were believed to be petrified dragon tongues. When ground into a powder and consumed, these “glossopetrae” were used to treat poison.

National Aquarium – Sand Tiger Shark

8. Sharks can’t get cavities. Sharks don’t have to worry about a visit to the dentist, because their teeth contain fluoride, protecting their mouths from cavities. The fact that they’re constantly replacing their pearly whites can’t hurt either.

For more on shark teeth, listen to this week’s episode of A Blue View:

Episode Transcript

Ask a young child to draw a shark and odds are she’ll pick up a gray crayon, draw a torpedo-shape on the page and complete the picture with an Impressionistic dorsal fin and tail, and an impressive mouth of teeth. Kids seldom forget the teeth.

In Peter Benchley's “Jaws,” arguably the most infamous great white shark tall tale ever told, Carcharodon carcharias is described as being “like a locomotive with a mouthful of knives.” With a multiplicity of thin wafer-white triangles, each one dangerous and serrated, we know a top predator when we see one. The great white shark is the largest predatory fish alive. But how did the great white get those teeth that are so iconic that even a toddler can expertly draw them?

Ancestors of the great white shark had smooth, unserrated teeth, because they were primarily fish eaters. But somewhere along the evolutionary tree something happened, and those famous pearly whites started evolving.

Evidence of this comes from fossil yards in southwestern Peru, a desert area famous for numerous well-preserved remains of ancient sea creatures, like an incredible find in 2009: a set of 40-million-year-old vertebrae and teeth of an early mako shark. Why was this so important? Because its teeth were lightly serrated. And when scientists talk about evolutionary advantage, most agree that when sharks began to show up with serrated teeth, they branched out from being exclusively fish eaters to being true carnivores, who feasted on both fish and marine mammals.

Marine mammals are a bigger, stronger and altogether tougher meal, but a great white’s serrated teeth can rip and shred all that skin, blubber and bone. Seals are the great white shark's preferred food, but these apex predators also eat many other species, including sea turtle and tuna. They take huge chunks out of dead whales. They've even been known to eat sea birds, leaping dramatically out of the water to snare a petrel or shearwater.

These sharks have earned their top-of-the-food-chain status. First, they’re opportunists, with teeth that can be up to 3 inches long. Great whites have 26 teeth in each row of the upper jaw, 24 in each row of the lower jaw, and two or three functional rows. And behind those, rows and rows of baby teeth grow in a special membrane that continually unfurls like the treads of a tank.

The great white is constantly shedding and growing teeth. Just one animal can go through 50,000 teeth in its lifespan. Remarkably those terrifying teeth have actually evolved from harmless skin. That’s right—the skin of sharks and rays is not covered in scales like that of bony fish. Instead, it’s covered in tiny overlapping V-shaped bodies called dermal denticles. They give the skin a rough texture, much like sandpaper. In fact, in the days before commercial sandpaper, dried shark skin was actually used as an abradant.

Shark teeth are basically enlarged and specialized dermal denticles! That doesn't sound scary, does it?! Well, perhaps if you’re a seal.

From tooth to tail, great white sharks are fascinating. To learn more about be one of the Earth’s great predators and its amazing teeth, please visit aqua.org/ablueview. This is John Racanelli for WYPR.

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