Megalodon

We’re not sure how big megalodons were, but this gives you a general idea. Compare it to the more accurate estimates below. Dinosaur Zoo, CC BY-SA 3.0.

The biggest known shark, and fish of any kind, was megalodon. We don’t really know how big it was since so far paleontologists have only teeth and a few vertebrae. It had cartilage instead of bone, and that doesn’t preserve well.

One estimate suggests it was plump and stalky, similar to great white sharks, and could get from fifty to sixty-five feet long (15 to 20 m). At the upper end, it would be roughly as long as a six-story building is high, or longer than an 18-wheeler tractor-trailer truck. Just think about that the next time you pass one on the highway. Imagine that it’s a megalodon swimming beside you, eyeing you with delight at having found a little snack.

Another estimate suggested it may have been longer and thinner, more like a mako shark, which would mean it was slower, less maneuverable, and unable to accelerate as quickly. While the second study refrained from giving an estimated size, one of its authors and their illustration indicated a range from fifty-five to seventy-nine feet (16.5 to 24 m).

It’s thought they weighed around fifty-five tons (50 tonnes)—roughly equal to eighteen large elephants, or about twenty-five great white sharks. And a man could stand on one’s back and would be about as tall as its dorsal fin. It was quite a large shark.

Megalodon means “big tooth” and its teeth were certainly big—about the size of a man’s stretched-open hand. It had five rows of very large teeth—276 of them, most of which were replacements for those that broke off.

Some evidence indicates that they were partly warm-blooded—meaning they kept their body temperature higher than the water they swam in—just as great white sharks, mako sharks, and a number of other sharks do today, but not quite the way we do. Because of their size, they probably had an even higher body temperature than those sharks. This would have made them more active and able to swim faster and for longer distances, but it also would have required them to burn through more food.

Megalodons were swimming around for about twenty million years, which is pretty good considering our species has only been around for about 315 thousand years. They first appeared around 23 million years ago—about 23 million years after the dinosaurs went extinct—and they disappeared 3.6 million years ago. There is no evidence of any megalodons existing since then. If they had, there would definitely be signs of their existence. They were gigantic apex predators that required a huge amount of food to survive.

Now, these are jaws.

Their primary prey were whales, seals, large fish, turtles, and other sharks. They could have eaten an orca in about five bites with their huge mouths, the largest being eleven feet wide by nine feet high (3.4 by 2.7 m). Scientists estimate its stomach could hold a twenty-six-foot-long (8 m), 6.6-ton (6 tonnes) orca. A meal like that could last it for two weeks, but they probably didn’t eat a complete whale.

It looks like they enjoyed eating just the faces of sperm whales—as do mako and great whites—leaving the rest behind for other creatures to eat. Sperm whale noses contain a lot of fat and oils, which sharks used to love devouring. Modern sharks no longer kill sperm whales, but orcas do.

Most whales were smaller back then, although by around seven million years ago the largest sperm whales did get up to the same size as a megalodon, but after megalodons went extinct, whales were free from their primary predator. As a result, they were able to grow in size to become the largest animals on earth. Blue whales evolved after the megalodon’s demise.

It’s not possible for one to still be hiding somewhere. While there are some areas of the ocean that aren’t frequently explored, such as the Mariana Trench, there’s not enough food in the deep ocean to feed such a huge animal, so it would have to live closer to the surface, and there would be some traces if something was killing that many whales. While we do continually discover new creatures in the ocean, nothing is anywhere near megalodon’s size. If they were still around, they probably would have evolved into something much smaller, but so far there’s no evidence of that either.

Several things could have caused megalodons to die out. At that time the earth was getting colder and that could have greatly reduced their food supply. Also there was a large drop in sea level from 5.3 million to 2.6 million years ago. This shrank their coastal habitat, reducing both their prey and their living space. Scientists suspect they may also have suffered from competition with great white sharks, which had appeared on the scene by that time. Sea levels today are even lower than they were then, although they are now rapidly rising again.

There may have also been changes at the locations where megalodons raised their young. So far researchers have found four of these nurseries covering different periods of time. They’re in Spain, Panama, Chesapeake Bay, and Florida. Most of these are now inland. They indicate megalodons devoted time to caring for their young, which weren’t fully grown until the age of twenty-five.

Now, you may be surprised to learn that a toothed whale grew to be just as large as megalodon. A fossil of one was found from twelve million years ago, right in the middle of megalodon’s reign and at fifty-five feet (17 m), it was about the same size. And, being a toothed whale, it had teeth, perhaps for fighting off or eating megalodons. It’s called leviathan and is thought to have looked like a sperm whale, but where sperm whales only have teeth in their lower jaws, leviathan had teeth twice the size in its upper and lower jaws, and unlike sharks, whose teeth are embedded in their gums, leviathan’s teeth were embedded in bone.

 

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