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megalodon

I lived through that great Shark Week debacle in 2014, when the usually fairly reputable Discovery Channel showed this bizarre pseudo-documentary called Megalodon: The Monster Shark Lives. I believe I watched all of five minutes of this monstrosity, and I knew that the thesis posited in the film, that there really still are Megalodon sharks swimming the seas, would be taken as fact by a certain percentage of the credulous public.

If such an animal really does still live in the ocean, then small to medium-size craft could be endanger at all times, but of course, no real evidence of late surviving Megalodon has ever been produced.

Indeed, when this documentary came out, I was quite aware that some shark specialists were doubtful that these large sharks survived into the Pleistocene.

Well, we now have some really good evidence, based upon an extensive re-evaluation of the fossil record of Megalodon sharks, that the species went extinct about 3.51 million years ago. It was previously believed that the species went extinct 2.6 million years ago, and recently, a supernova was suggested as the likely culprit.

However, this new date means that the supernova probably did kill off lots of large marine mammal, but the Megalodon had already been gone for about a million years before the supernova hit.

This new study, published in PeerJ, contends that the species became extinct as the modern great white shark spread over the world from its ancestral home in the Pacific Ocean. Great whites became widespread in the world’s oceans around 4 million years ago, and their spread roughly coincides with the new extinction date for the Megalodon.

The authors contend that the juveniles of the Megalodon were unable to compete with the adult great whites, and because a species cannot exist very long if its young never survive, the great white might very well be the culprit behind the extinction of the Megalodon.

So no, Megalodon doesn’t live. Jaws took it out long ago.

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Megalodon hunting juvenile blue whales. White sharks don't get this big. The Megalodon may not have reached this size either.

Megalodon hunting juvenile blue whales. White sharks don't get this big. The Megalodon may not have reached this size either.

I’m sure everyone has seen  Jaws, along with all the cheesy sequels. They are rather like bad rip-offs of Beowulf. Just when the large white shark is killed, another even bigger one shows up, probably its mother out to avenge the death of its offspring.

But how big do white sharks get?

That is something of a debate.

The one in Jaws was 25 feet long, which is actually not much larger than the species gets according to official sources. In one of the cheesy sequels, the shark is 35 feet long.

But how big do they get?

Officially, their record size is around 20 feet. The largest on record was caught off the coast of Cuba. It was 21 feet long, just slightly smaller than the shark in Jaws.

However, there are reports of white sharks exceeding 30 feet in length. These must be taken with a grain of salt.

Why?

Well, there is a somewhat similar species of shark that does attain those lengths. Today, we know them to be very different from the white shark. I am, of course, talking about the basking shark. Basking sharks can reach lengths approaching 40 feet, and if one is seen swimming in the water, it looks something like a white shark. But it lacks the rows of sharp teeth, for it is a filter feeder. To make things even more confusing, different authors refer to the white shark as a “basking shark,” including Kipling in his short story “The White Seal.”

The supposed largest white shark was taken in herring weir in New Brunswick. It was said to be 37 feet long. However, the largest basking shark was caught in the Bay of Fundy, not very far from where this supposed white shark was captured. It was caught in a herring net, which does suggest that the animal in both cases was the basking shark.  Herring and basking sharks eat the same plankton, and it would be reasonable to find herring and basking sharks in relative proximity to each other.

White sharks also avoid boats. They seem to know that people are forever gunning for them, so if they see a boat, they usually try to avoid it. A basking shark will ignore the boat and continue slowly swimming. That means that the basking shark is more easily taken by fishermen than the white sharks are. And it would make sense that such large sharks wound up captured by herring fishermen.

So we can dismiss the New Brunswick giant white shark as a big basking shark.

But are all of these animals misidentifications?

There is always this Megalodon hypothesis that pops up now again. Supposedly, there is a relict population of Megalodon stalking the depths of the world’s oceans. It is most likely poppycock.

The Megalodon is thought to be a close relative of the white shark, and some taxonomists place it in the same genus as the white shark. It is believed to have reached a length of over 50 feet. And its diet was mostly whales and other marine mammals. It most likely became extinct 1.5 million years ago.

It may have been in the same genus as the white shark, and it is thought to have looked a lot like the white shark, just much larger. My guess is that the oceans of today simply do not have enough marine mammals to even support a relict population of this species. During its halcyon days in the the  Miocene and Pliocene, there were many more species of whales and other large sea mammals. The numbers of these creatures dropped off in the Pliocene, and those that remained migrated to the polar regions, where the shark could not survive.

So it is very unlikely that the supposed giant white sharks are actually Megalodons.

So how big do white sharks get?

Well, we have some numbers based on authenticated records.

We have three recent reports of 23 foot white sharks. These have been met with scrutiny, and one of them has been disproven. In 1987, a supposed 23 footer was caught off the coast of Malta, and that same year, another alleged 23 footer was caught off the coast of Kangaroo Island, South Australia. The one in Malta was later analyzed based upon its photograph to be no more than 18 feet long. The one in Australia has not been verified. However, another was caught in 1997 in Taiwan, it was also said to be 23 feet long, but again, no one has verified its size.

The official world record length for the white shark is 21 feet, which was captured off the coast of Australia. There have been several reports of 20 footers, including one that showed up in Prince William Sound, Alaska, were it tried to steal a Pacific hailbut from the line of sport fishermen.

19-21 feet seems the most likely maximum size for the white shark. It is possible that larger fish existed long ago. After all, one thing ichthyologists have noted is that fish specimens have decreased in size. over the years. This reduction in size has been observed in so many species, some of which were taken as trophies by sport fishermen and others were taken for their meat. Large sharks were probably taken because of the supposed threat they posed to swimmers. Like ridding the forests of wolves, bears, and big cats, man believed that removing large predators from the ecosystem was a duty. It has only been recently that we have realized the error that was made.

So maybe there really were 23 foot white sharks.

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