Megalodon (Carcharocles megalodon) is the largest shark, at a magnificent maximum length of 18 meters (59 feet), to ever have dwelled in the oceans.  We know primarily about Megalodon’s existence through fossilized teeth.  Megalodon’s maximum size is inferred because we do not actually have a whole preserved Megalodon.  Using a mathematical relationship between body size and tooth size for Great Whites, we can estimate Megalodon’s size from its teeth.  In fact, my former graduate student Meghan Balk, with Catalina Pimiento, used this method with oodles of Megalodon teeth to show that Megalodon did not change much in size when it did exist.  But I digress.

A recent Twitter exchange made me realize that both some people think Megalodon still exists and a really good write up on how we know Megalodon actually does not exist is not on the interwebs. So in a numbered list, here we go.

No teeth. Sharks repeatedly shed and replace teeth. Go beach combing and you are likely to uncover teeth from sharks that dwell in the area.  We know about Megalodon primarily through fossilized teeth.  Although much to my amusement, fossilized poo, called coprolites, are also attributed to Megalodon.  A couple of vertebra columns have also been discovered.  These Megalodon teeth date from 23 million to 2.6 millions years ago.  After that, zero Megalodon teeth.  So if Megalodon existed now we would not only see Megalodon teeth all over today, as we do for other sharks, but with would have fossilized ones from the last 2.6 million years.  By the way, Megaldon teeth are pretty recognizable and distinctive, beyond just size, from other extinct sharks and the Great White. Researchers would not be confused if a tooth was from Megalodon.

No bite marks. Although much rarer than fossilized teeth, fossils also exist of whale bones with Megalodon tooth slashes and bites in them.  We have none of these type of fossils from the last 2.6 million years.  There is also no contemporary evidence from carcasses or bodies of whales of bite marks or wounds consistent with a large shark like Megalodon.

Not lurking in the depths. Everything we know about Megalodon suggests it was a large shark preferring tropical/subtropical warm waters.  Indeed, one hypothesis for its extinction was that the oceans got colder.  This warm temperature preference means that Megalodon is not hiding in the unexplored, deep and cold parts of the oceans that we have not explored.  Megalodon would literally be near the surface in plain sight.

Huge sharks exist: Huge sharks like sleeper, Greenland, basking, whale, Great White, and 7-gill are practically seen every day.  They all are very big and often mistaken for a Megalodon.  A group of colleagues and I actually researched how big some of these actually can get. But none of these are nearly large enough to come close to the estimated lengths of a Megalodon nor are their shapes consistent with what a Megalodon would like like.  Update: as noted below the largest known whale sharks actually do obtain Megalodon lengths.

Different oceans: The oceans with a massive ocean predator like a Megalodon would look a lot different structurally.  What do I mean?  Without going into all the specific science here, large predators have a huge influence on ecosystems and food webs, especially prey items.  When we look at ocean ecosystems and food webs there is no evidence that they could or do support a massive ocean predator. Again, one of the hypotheses for the extinction of Megalodon is that a changing ocean around 2.6 million years ago could not produce enough food for a massively-size carnivore like Megalodon.

1 Megalodon, 2 Megalodon, 700,000 Megalodon. For Megalodon to have existed 2.6 million years since the last known fossil tooth, there would need to be a sustainable population. Based on its size (you can see how this is done on my Kaiju post) we would expect global numbers, if we assume the largest Megalodon females get is 65.5 tons, of near ~700,000-1.5 million.  A lot of assumptions here.  Since we don’t have a relationship for shark abundance and size, I used the relationship for carnivorous mammals.  I also provide estimates for 50% (lower estimate) to 100% (higher) of the ocean being warm enough for Megalodon. Obviously this is crude estimate, but the point here is that there would be quite a few Megalodon in the oceans.  Now their numbers might be quite a bit less if Megalodon was going extinct.  But in the modern oceans, the primary way large marine animals go extinct is by human hunting.  Megalodon should be in nets and markets if this was the case.  Which brings me to my next point…

Underestimated commercial interests: If a 50-ton shark existed in the ocean, then commercial fishing operations would ensure Megalodon would have been found and on plates throughout the globe. Currently a pound of Mako is running $30 per pound. An average size Megalodon would bring in $3 million dollars at this price.

Fake documentaries and videos: Many people still think Discovery Channel’s fiasco of a media is real documentary.  It was not. Indeed, the original documentary actually had a too short and too hidden disclaimer.  Snopes has, as always, a great post about how this is fake.  Also the fake video of a Megalodon was actually a sleeper shark.

Government and scientific coverup:  I see this coverup language brought up a lot in discussions about climate change and other controversial topics.  I think this stems from a couple areas of misconception about how science is funded and how scientists interact.  Science is funded through multiple ways for scientists affiliated with universities, similar research institutions, or independents.  Government and corporate scientists are often funded by the institution and see more oversight.  Most funding for the former type comes from either foundations or the government.  You submit a grant and based on the quality, relevance, and importance of the proposed research you get might get funding.  This funding obviously dictates the larger theme of the research but does not dictate the findings, results, and conclusions of the research.  The concept of academic freedom, a scholar’s freedom to express ideas without risk of official interference or professional disadvantage, is by far one of the most cherished rights we have as scientists.  Many scientists would not work for institution or accept funding that would infringe upon this right.  I know of scientists who do research without funding even to pursue a course they are interested in.  Also, a government conspiracy to hide science would never be tolerated. Just look at the response from scientists to the current administration’s attacks and attempted cover up of climate science.  Second, there is no annual meeting where scientists meet to agree on what in the field to believe in or not.  Each scientist evaluates the evidence and data independently and draws the conclusions.  Consensus is reached when these scientists independently reach the same conclusion because the evidence is overwhelming.  Scientists actually thrive on disagreeing with one another.  Not about big things like if Megalodon went extinct or not, but why Megalodon went extinct.  I will finish by saying that if Megalodon still existed its discovery would greatly propel a scientific career.

The post How We Know Megalodon Doesn’t Still Exist? first appeared on Deep Sea News.

The other day I received a slightly disconcerting text message from my cousin regarding Shark Week. She has two young kids one age 6 and the other age 9. The conversation went a bit like this…

   Cousin: “The kids want to know…what is your opinion on Megalodon? They get all their scientific knowledge from Discovery Channel! =) But they want a real scientist’s opinion.”

Despite my better judgment (and because there was nothing else on T.V.) I had watched the Megalodon atrocity that kicked off what is usually my most favorite broadcasting week of the year. Appalled that this is what Discovery had resorted to, I sadly turned the channel and had decided that was enough Shark Week for me.

My reply: “<Insert Megalodon/Discovery Channel Rant>”

Eventually we talked it out and set the record straight for the kids and went about our lives. However, I just couldn’t shake the conversation.

Discovery Channel had let them down. It had let us all down.

In the past couple of days, I find comfort that the scientific community has made apparent their disapproval of these Shark Week shenanigans. But what about my little cousins? What about the others like them who “get all their scientific knowledge from Discovery Channel?” What is their take on all of this?

I wanted to know. So I asked. We ended up talking for 45 minutes. And let me tell you, there is nothing more humerous, interesting, and ultimately telling than Shark Week from the perspectives of a 6 and 9 year old.

They didn’t know whether or not to believe that Megalodon was somewhere to be found off the waters of South Africa. Hence their earlier inquiry. They did call Discovery out on their shotty animations (to which I laughed), but they didn’t know that the scientists were actors (to which I didn’t). In fact, they were shocked when I told them. They believed in the evidence of a half bitten whale.

“They spread that information out there, and then people start thinking it’s real. Then they start getting afraid of sharks, and then they start killing them…and that’s a problem.” A direct quote….from a 9 year old.

When I asked them how they would know if a scientist was real or not? They said they didn’t know and that was a hard question. Honestly, would you know?

We went on to talk about their favorite shows, the ones that told them cool facts about sharks. They wanted to know more about ones that lived in the deep and didn’t want to see people getting eaten, but rather to see them actually interacting with sharks.

I asked if some of the shows made them scared to go in the water. “Kind of,” they replied. They didn’t want mom paddle boarding out there, because they had seen a paddle boarder with sharks all around them.

We discussed shark conservation. What they did know about shark finning they didn’t get from Discovery Channel, but they thought it was something people needed to know about.

Eventually, they turned the tables on me and started asking the questions. Why are some sharks aggressive? What is the average length of a shark? How fast do they have to go to jump out of the water? If it wasn’t for our limited time, I don’t think the questions would have stopped.

Throughout this entire conversation, sometimes they would cite word for word something they had watched on Shark Week. These kids are paying attention.

DISCOVERY CHANNEL. THESE KIDS ARE PAYING ATTENTION.

We ended our most enlightening conversation by discussing the role sharks play in the ecosystem. Not only did they understand, they were the ones who told me. Asking if they had heard that on Shark Week, they said no, but concluded with “Isn’t that the stuff people need to know though?”

I adore my little cousins and hope that they inspire you as much as they inspire me.  They love and respect the ocean. I have even kept this on the fridge for the past couple of years to remind myself that they look up to me and as such I must set the best example I possibly can. Thus, I resume watching Shark Week despite my disgust, so that I may continue this conversation with them. They deserve the truth and I don’t want to let them down.

The post Why I Still Watch Shark Week first appeared on Deep Sea News.

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