Science, Now + Beyond

“The Meg” briefly reveals the real villain of the oceans

No, the megalodon is not still lurking in the deepest parts of the ocean. The real threat in the waters is human

Ever since Jaws was released in 1975, shark movies (of wildly varying quality) have played an important role in the world of summer blockbusters. The allure of the shark as antagonist in film is pretty clear: it’s an apex predator, swimming at the top of the food chain. And while shark encounters with humans are actually fairly rare, they have all the elements for big-screen drama: big, sharp teeth, blood in the water, unexpected violence interrupting ordinary human activity.

So sharks have found a home in our imaginations, but the films that feature them are generally pretty light on science, despite the fact that the characters featured are often scientists. This summer’s addition to the shark film catalogue, The Meg, rests upon a supposition almost as outlandish as the idea of sharks deliberately stalking people as prey. (Almost.)

A team of researchers in a lab off the Chinese coast have discovered a trench that descends deeper into the ocean’s depths than the Mariana Trench, somewhat sealed off from the rest of the ocean by a layer of cold water and some sort of gas. Scientists breach that seal in a high-tech submersible and enter into a secret part of the ocean warmed by volcanic ports, and containing new sea life.

And old sea life: a megalodon, the largest shark ever documented, thought to be long extinct.

Now, we don’t have time to go into all of the science depicted in The Meg. So for now we’ll focus on the most critical plot point: a real life megalodon, alive millions of years after its species supposedly went extinct. What is the likelihood that megalodons could be lurking somewhere in the deepest parts of the ocean, hidden from humanity for all this time?

Turns out, the odds are basically nil. The last signs of the megalodon in the fossil record are dated to about 2.6 million years ago, about a million years before our earliest Homo sapiens ancestors started appearing. The idea that megalodons could have remained at large for so long without leaving any trace that appeared in fossil records is pretty improbable.

Then there is the issue of size. The megalodon was probably about three times the size of the largest great white sharks, about 60 feet long. Sustaining a body that big requires a lot of food. Scientists think that the megalodon fed on prehistoric whales and other large sea creatures and had to eat a literal ton of food every day. So for these sharks to still be alive, they would need to be feeding on other large sea animals. The Meg’s secret sea trench would have to contain a closed ecosystem of giant marine animals to sustain a top predator as large as the megalodon. So this isn’t just a question of whether one big species could be hidden from human eyes, but whether a major community of them could be. Again, unlikely.

In fact, scientists now think that one of the reasons the megalodon went extinct was competition for food. New, smaller, more agile species like the great whites and orcas that we have today emerged and ate some of the prey that the megalodon depended on. As the competition increased, the megalodon couldn’t hunt enough to survive.

Most animals that do live in the deepest parts of the ocean are slow-moving, and have to be able to survive on small prey, since the depths are so sparsely populated. The megalodon simply wouldn’t be able to consume enough calories to live down there.

All the fossil evidence we do have indicates that the megalodon preferred warmer, shallower waters, and used shallow coastal seas as nurseries.

And speaking of that fossil evidence, most of it is teeth. Megalodons, like most sharks, would have shed teeth regularly as new ones grew in. Sharks can shed up to 20,000 teeth in their lifetime. If the megalodon was still alive somewhere, its teeth would have to turn up periodically.

But The Meg doesn’t get everything wrong. There is a brief but important moment when the researchers in the film encounter the bodies of smaller sharks floating atop the ocean, their fins cut off. When one character asks what happened, the head of the research station explains that the sharks had been finned and thrown back, because shark fin soup is an expensive delicacy in parts of the world. It was a small reminder in the midst of a big, silly action movie that humans pose a far greater threat to sharks than sharks will ever pose to us, and that we are often the ones who hunt them maliciously, not the other way around. The practice of shark finning may kill up to 100 million sharks a year.

We love shark movies because it’s easy to make sharks seem like the biggest, baddest predators around. But their place at the top of the ocean food chain doesn’t keep them safe from the dangers of human greed or ignorance.