The megalodon, a prehistoric shark that would dwarf even the largest great white, hasn't roamed the seas for millions of years. But it's inspiring real dread today, thanks to a new documentary that aired Sunday night on the Discovery Channel and that critics are decrying as fake.
Called "Megalodon: The Monster Shark Lives," the two-hour documentary, which Discovery calls "dramatized," kicked off the channel's annual "Shark Week." It featured actors pretending to be scientists who are hunting for a live 67-foot-long (20-meter-long) megalodon nicknamed Submarine that is terrorizing humans and their boats off the coast of South Africa.
The show sparked online outrage, as viewers took to Twitter to blast what they called a "mockumentary" under the hashtag #megalodon and to demand an apology from the network.
Also on Twitter, @chrishildreth referred to Shark Week as "Lifetime for animals now. Drama and bad acting," while @JBMason628 said, "As a scientist, I have completely lost faith in @Discovery trying to pass off #megalodon as real science."
Discovery aired disclaimers at the end of the show, but also insisted that "though certain events and characters in this film have been dramatized, sightings of 'Submarine' continue to this day."
The network's insistence—against all scientific evidence—that megalodon might still live angers and exasperates shark scientists like David Shiffman.
"If this megalodon special had aired on the Syfy Channel, I probably would have loved it," said Shiffman, a doctoral student studying shark ecology and conservation at the University of Miami's Abess Center for Ecosystem Science and Policy.
"But Discovery bills itself as the premier science education television station in the world," he said, "and they're perpetuating this utter nonsense."
Shiffman has been one of the show's most vocal critics on Twitter, where he tweets under the handle @WhySharksMatter.
A Prehistoric Monster
It's easy to understand why Discovery chose megalodon to kick off this year's Shark Week, though. Growing to an estimated length of over 50 feet (16 meters), megalodon—literally "megatooth"—resembled something out of a prehistoric nightmare and has no modern equivalents in terms of size.
"A great white is about the size of the clasper, or penis, of a male megalodon," Peter Klimley, a shark expert at the University of California at Davis, said in a 2008 interview.
Some studies suggest megalodon, which lived from about 16 million years ago until about 2 million years ago, had the most powerful bite of any creature that ever lived—strong enough to crush an automobile and far stronger than that of the great white shark or even Tyrannosaurus rex.
Another example of how intimidating megalodon could be: Where modern great whites hunt dolphins, scientists think megalodon hunted whales, or at least their ancestors, by biting off their tails and flippers.
"Modern great whites will scavenge on a whale, but not actually take a [live] whale," Klimley said in an interview Tuesday.
Like modern sharks, megalodon's skeleton was made mostly of cartilage. As a result, nothing remains of the creature except its teeth, which were made of a bone-like material.
That's enough, though, for scientists to get a sense of what megalodon looked like. "You can tell a lot based on just small parts of the bone," Shiffman explained. For example, "a lot of dinosaurs are known from a small part of bone."
Although the megalodon dwarfed its living cousin—the great white—in size and weight, scientists say the great white actually looks pretty similar, with both possessing large teeth and a blunt snout.
"If you picture a megalodon as a 50-foot [16-meter] great white, you're well on your way to what this animal was probably like," Shiffman said.
For reasons that are still unclear, megalodon went extinct about 2 million years ago, during the middle Miocene era.
One hypothesis, said Klimley, is that megalodon was unable to adapt to changing ocean conditions.
Megalodon thrived during a time when the Earth's oceans were generally much warmer, and conditions were much more uniform.
But throughout the Miocene, the Isthmus of Panama started forming, culminating with the closure of the Central American Seaway around 3 million years ago.
This shut off any exchange between the Atlantic and Pacific oceans, and one consequence of this was that regions of Earth's seas became cooler.
Unlike its cousin the great white, megalodon may have been unable to evolve endothermy, or the ability to maintain an elevated body temperature, scientists say.
"White sharks are able to occupy cooler waters right now from off the coast of central California to Oregon," Klimley explained.
"These cooler waters extended northward, and [seals and dolphins] and whales also moved farther north in latitude, but megalodon was not able to do that."
Another factor in megalodon's decline may have been the rise of competitors such as killer whales. "Being social hunters, it has been suggested that they out-competed megalodon's hypothesized solitary hunting style," Catalina Pimiento, a shark researcher studying megalodon at the University of Florida, explained in a recent blog post.
Pimiento argues that studying extinct sharks like megalodon can have implications that are relevant to today's world.
"Great sharks today, like Megalodon in the past, are apex predators impacting communities via top down control," Pimiento wrote.
"As we change the oceans, we also trigger cascading effects on entire ecosystems. Understanding the past—how this shark interacted in its community—can aid in making policy for marine systems."
Many scientists are upset by Discovery's dramatized show about megalodon because they say it uses fear and deception to generate public interest in the shark.
"It's kind of irresponsible," Klimley said. "It's just making something up to just scare people ... At least the movie Sharknado was kind of fun. It's so outlandish that nobody is going to take it seriously. But this is the kind of thing that people might take seriously."
Shiffman worries that fear could have a chilling effect on shark conservation programs. "There's a lot of people who now say because they saw it on the Discovery Channel, that megalodons are real, and we have to launch a campaign to protect humans against them by killing sharks," he said.
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