What ate a 3 meter long Great White? Probably a Wereshark

Recently a 2003 video went viral on the internet.  The video is a story of a 3 meter Great White Shark that was tagged.  That electronic tag eventually washed up on a beach.  The data from the tag seem to suggest, at least to the narrator and some others on the internet, that a massive ocean monster ate the shark.  The main line of evidence for this is that the tag recorded a temperature of 78˚F.

a temperature that can only be achieved inside the belly of another living animal


To recap the facts (in so much as the facts are accurate on the video)

  • At an undescribed location on the Australian Coast a female 3 meter shark was tagged.
  • The female, called Shark Alpha, was observed to be healthy and the tag was perfectly placed.
  • Four months later the tag was found by a beach comber 2.5 miles from where Shark Alpha was originally tagged.
  • Data from the tag indicated that at 4:00 am on Christmas Eve, the tag went quickly to a depth 580 meters (1903 feet) on the continental shelf.
  • The tag detected at 580 meters a temperature shift from 46˚F to 78˚F
  • The recorded temperature of 78˚F lasted for eight days while the tag moved from a depth of 330 feet to the surface.

The narrator of the video, the “researcher” in the video, and others on the internet suggest these facts are consistent with Shark Alpha being eaten by a much larger mysterious predator.

Australian researchers are hunting for what they call a “mystery sea monster” that devoured a 9-foot-long great white shark.-CNN

Multiple news agencies are thankfully pointing out that there really is no mystery here.  Well of course there is the mystery of why Scienotainment TV Channels keep spreading the story of a magical ocean full of mermaids, sea monsters, and the long extinct megalodon, but I digress.

As reported at NBC

“I don’t know this story,” R. Dean Grubbs, a shark researcher at the Florida State University Coastal and Marine Laboratory, told NBC News in an email, “but it doesn’t take some mysterious giant shark to eat a 9-foot white shark.” Grubbs said he’s had more than one 10- to 12-foot-long tagged shark eaten by other sharks. “Two 10- to 12-foot sixgill sharks were eaten by what we believe, based on the vertical tracks, were larger tiger sharks,” he wrote. “And one 10-foot tiger shark was eaten by what we are pretty certain was a larger sixgill shark. I have also caught multiple sharks that would have been over 10 feet, but only the head remained.”

One possibility raised is a cannibalistic and larger Great White ate Shark Alpha.  Well that is certainly reasonable although not nearly as entertaining.  Work by my student Lindsay Gaskins as part of her work for Sizing Ocean Giants is presented below.  In terms of all Great Whites ever measured, and where we could access the size measurements, Shark Alpha is not very big. Indeed, 75% of the approximately 800 Great White Sharks we have measurements for are larger than 3 meters.

Historgram of sizes of Great White Sharks.  Unpublished data from L. Gaskins

Historgram of sizes of Great White Sharks. Unpublished data from L. Gaskins

When I was undergraduate I learned a great principle that I continuously apply in my career as a scientist.  KISS. Keep It Simple Stupid.  In other words, the simplest explanation is likely the correct one.  No need to make up a super predator when 75% of measured Great Whites are larger than the focal shark.

But of course I suppose that doesn’t make for good ratings.  So in an attempt to get massive hittage on DSN, I propose a wereshark ate Shark Alpha.

Known only to few people, Great Whites actually turn into weresharks during full moons. Image courtesy of Shutterstock.

AWOOOO! Known only to few people, Great Whites actually turn into weresharks during full moons. Image courtesy of Shutterstock.

 

 

 

 

 

Dr. M (1628 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, created to facilitate research to address fundamental questions in evolutionary science. He has conducted deep-sea research for 11 years and published over 40 papers in the area. He has participated in dozens of expeditions taking him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses mainly on marine systems and particularly the biology of body size, biodiversity, and energy flow. He focuses often on deep-sea systems as a natural test of the consequences of energy limitation on biological systems. He is the author and chief editor of Deep-Sea News, a popular deep-sea themed blog, rated the number one ocean blog on the web and winner of numerous awards. Craig’s popular writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.





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16 comments on “What ate a 3 meter long Great White? Probably a Wereshark
  1. I thought the conclusion they reached was that a killer whale ate it, and that it was indicative of some unusual behaviour by the killer whales in that area. The full hour long show aired here in Australia a while ago, and I watched it at the time and found it quite interesting (though not at all what I was expecting for, since I was in the mood for some crazy cryptozoology at the time ;-)

    I’ll have to see if I can find it somewhere and have another look.

  2. KISS – also known as Occam’s Razor! http://en.wikipedia.org/wiki/Occam's_razor

    With apologies to widipedia:
    Possible explanations can become needlessly complex. It is coherent, for instance, to add the involvement of leprechauns (or weresharks) to any explanation, but Occam’s Razor would prevent such additions, unless they were necessary.

    • I agree that in this case “Occam’s Razor” has it’s uses, but it is a simply a basis for constructing a hypothesis. This is not the same thing a functional theory, which may be considered the “truth.”

      For this reason, and not to attack your logic, I have written this for you and others to consider when examining the unexplained.

      First understand the origins of Occam’s Razor.

      Occam’s Razor is a positivistic form of thinking; which is a mechanical automatic response without brains.

      The premise of Occam’s Razor is; “the explanation with the least amount of assumptions contained is the most likely explanation,” is itself stupid, because Occam’s Razor is the ruling assumption in how to reach a supposedly logical conclusion, and which is supposed to, “somehow,” be some kind of truth: As in open and shut case. This is mechanical automatic reflex like thought process.

      That is positivism defined.

      http://www.britannica.com/EBchecked/topic/471865/positivism

      There are many pitfalls when applying Occam’s Razor to investigation in general, and this is why detectives use another method.

      Most scientists are very unfamiliar with concepts of criminal investigation whereby an investigator may have to construct several hypothesis, and all of which may seem plausible. Indeed, that is the general idea behind most murderers clues isn’t it?

      Consequently, it has been my experience that there is an inadequate comprehension of the scientific method as applied to forensic investigation.

      Occam’s Razor can be seen as point of departure. In other words, a fine place to begin. It may provide the answer to a incident, crime, ect, but it is by no means the same thing as truth.

      Investigators use a form of Null Hypothesis Theorem to find the most likely explanation. Occam’s Razor is in way superior to any other hypothesis. It’s just simpler, which often tends to be good starting point
      in constructing a hypothesis. It is certainly not a place to stop and reach a conclusion.

  3. This is a witless article.

    The thesis statement is, “The main line of evidence for this is that the tag recorded a temperature of 78˚F.” And then you go on to debunk only the fact that a 9-foot shark could have been eaten by any number of larger sharks.

    Of course it could have. That is not the piece of evidence that has people scratching their heads. It’s the temperature. At depth. Of 580 meters. Where the water is near freezing. A great white’s stomach can get 25˚F hotter than the surrounding water, not 50˚F, which is why most think it was likely an Orca. Though they apparently don’t dive to that depth, hence the mystery.

    Of course it’s no monster, and I would put money that only the media implies it’s something mythical. Scientists or “researchers” may not know, but would have very logical and evidence-based hypotheses about possible explanations, none of them involving Shark Unicorns.

    I am no scientist, but your logic fails miserably. You kept your argument so simple you didn’t even make one.

  4. This article is impressive, on two counts.

    Perhaps ten percent of great whites are 6 – 7 meters long and a few are longer. Wow!

    And a professor credited his student. This is unheard of in academia. Wow! Wow!

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