In 1875, the British survey ship HMS Challenger was dredging the sea bed around the island of Tahiti. Amongst the strange artefacts that they pulled from the sea floor was a pair of huge teeth, the like of which they had never seen before. Serrated like those of a great white shark, the teeth were as long as a man’s hand, suggesting that they belonged to a vast marine predator. It was one of many curiosities picked up by the vessel on her four-year voyage of discovery (1872-1876), during which thousands of new species were recorded for the first time (http://www.huntsearch.gla.ac.uk/cgi-bin/foxweb/huntsearch/DetailedResults.fwx?collection=all&searchTerm=V5732&mdaCode=GLAHM&browseMode=on).
The teeth belonged to the megalodon: a giant, extinct species of shark. Since that time, more evidence for this astonishing creature has been found, including further examples of its teeth and parts of the animal’s vertibra. Using this evidence, modern scientists have estimated its length at 16 metres, making it the largest shark ever known, even in comparison with the whale shark. The megalodon’s dorsal fin alone would stand at 1.70 meters, about the height of an adult woman. If this shark came chasing after you on your jet ski, you’d know about it.
Ever since its discovery, cryptozoologists have wondered whether somewhere in the ocean, the megalodon might still exist. Let’s examine the evidence. First of all, the History channel has reports of seal carcasses having been ripped apart off the Sea of Cortez in Mexico, bearing the marks of an attack from an enormous predator: http://www.history.com/shows/monsterquest/interactives/monsterpedia-mega-jaws#mega-shark. The sea there could certainly conceal such a massive animal: in some parts, it’s 2,000 fathoms deep.
A shark of this size would need to eat a lot. Scientists estimate that an adult megalodon would consume about 1,000 kilos of meat per day. From tooth marks on fossilised bones, we presume that megalodon hunted whales, especially the sperm whale, their rival for the status of largest marine predator of all time. An adult sperm whale can weigh around 40,000 kilos. Even accounting for the skeleton taking up a large part of that weight, there would still be plenty of flesh left over for a hungry prehistoric survivor. We also know that predator-prey relationships still exist between megafauna in the world’s oceans, for example, between the sperm whale itself and the colossal squid.
It seems highly unlikely that the modern oceans could support a sustainable population of megalodon, especially without us knowing anything about it. However, estimates of the population of the blue whale put it at under 10,000 individuals. It’s a tiny fraction of their pre-whaling population, but it does show that large sea animals can hang on to survival with very few numbers.
Furthermore, new shark species are still being described today. In 2011, an unknown variety of frill shark was caught off the coast of Namibia. This fish lives at incredible depths, up to 540 fathoms down (http://www.guardian.co.uk/science/2011/feb/13/frilled-shark-chlamydoselachus-africana?INTCMP=ILCNETTXT3487). It’s hardly small, either: these frill sharks are over a metre long.
The megamouth shark is even larger. First discovered in 1976, the largest specimen of this species was 5.5 meters long. Despite its size, only fifty individuals have ever been recorded. The megamouth wasn’t even dredged up from some remote location: it was caught off the coast of Hawaii. Since then, it has since been sighted all over the world. If these sharks can survive, why not the megalodon?
One striking detail about these recently discovered shark species is their bizarre appearance. This is true of many other sharks too. When modern illustrators depict the megalodon, they frequently draw it as a very large example of a great white. This is based mainly on those serrated teeth. However, is it possible that the megalodon actually looked completely different? Imagine if hammerhead sharks had also become extinct and the only thing remaining in the fossil record was a handful of teeth and a vertebra or two. Is there any possibility that an artist would draw them as they really are, with their surreal head shape? The hammerhead isn’t even the most extraordinary extant shark species. That status must belong to the scarcely believable goblin shark (http://seavenger.info/goblin-shark/):
So perhaps a little more creative license could be used here in imagining how the megalodon might have appeared.
Whether it still survives or not, the megalodon is a thrilling reminder of the diversity that still exists in shark species, and how fragile their existence is in an age of overfishing and extreme exploitation of the ocean’s natural resources.