Megalodon Was A Much Slower Swimmer Than Thought With A Huge Appetite

It ate big, but at the cost of something else.


Rachael Funnell


Rachael Funnell

Digital Content Producer

Rachael is a writer and digital content producer at IFLScience with a Zoology degree from the University of Southampton, UK, and a nose for novelty animal stories.

Digital Content Producer

An ilustration of a megalodon, mouth wide open, about to chomp on a group of much smallerwhales

Megalodon’s secret to achieving gigantism is revealed by tooth-like scales.

Image credit: Antonio Viesa/

Megalodon was a ferocious predator, but new research suggests that when it came to swimming, it was mostly pretty slow. The revelation follows the discovery of scales within rock pieces surrounding a previously described set of teeth from a megalodon fossil.

“Our big scientific findings come from ‘tiny evidence’ as small as grains of sand,” said DePaul University paleobiologist, Professor Kenshu Shimada in a statement, who told IFLScience that it’s been in the making since the mid-1980s. It was 1986 when Shimada received a phone call starting with “Guess what I found?” [in Japanese] from a fossil hunting buddy who discovered the original Otodus megalodon tooth set that sits at the middle of this new research.


Revisiting the tooth set from the upper Miocene of Japan revealed numerous fragments of tessellated calcified cartilage and placoid scales, sometimes called denticles. They’re spiny tooth-like projections (hence the name) that are exclusive to cartilaginous fishes, which include sharks.

Denticle shape can be used as an indicator of top swimming speed because they are an adaptation that decreases drag and turbulence, allowing fish like sharks to swim faster and more quietly. Generally speaking, small denticles help you go fast while bigger denticles make for slower swimming.

These are real megalodon scales, compared in size (very similar) to the tip of a 0.5mm pencil. Strangely, they look more like pieces of amber or glass
These are real megalodon scales, and that black thing in the corner? That's the tip of a 0.5mm pencil.
Image credit: DePaul University/Kenshu Shimada

The denticles lifted from the O. megalodon specimen had broadly spaced keels (about 100 micrometers apart [0.003 inches]), so the researchers looked at how they compared to extant open-water sharks. Once the results were in, the denticles painted a picture of a slower pace of life for megalodon.

"This led my research team to consider O. megalodon to be an ‘average swimmer’ with occasional bursts of faster swimming for prey capture,” described Shimada.


Interesting stuff, but it was also slightly confusing because another recent study from Shimada revealed megalodons were warm-blooded. What were they doing with all that heat if they weren’t active swimmers? Going hard at the buffet, apparently.

“It suddenly made perfect sense,” said Shimada. “Otodus megalodon must have swallowed large pieces of food, so it is quite possible that the fossil shark achieved the gigantism to invest its endothermic metabolism to promote visceral food processing.”

It’s giving food coma, and we’re here for it.

The study is published in Historical Biology.


  • tag
  • evolution,

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  • shark,

  • megalodon