Unprovoked shark attacks are rare, but they do happen. About 60-70 times a year, in fact; and about ten people a year die from them. However, there should be more: the great white shark, which together with bull sharks and tiger sharks cause most attacks, is a killing machine to an unimaginable degree. If attacking humans were among their usual entertainments and taking into account how exposed many human populations around the world are, these numbers would be much (much) higher.
That is why the unprovoked attacks of these sharks have been a zoological mystery of the first order. What happens when one of these predators attacks a bather? Why does it happen? How can we avoid it (if we can)? And perhaps not the most important, but the most interesting…. What does all this tell us about the nature of the king of the seas?
By dint of generating hypotheses and trying to disprove them, experts came to the conclusion years ago that the explanation could be very simple: the sharks simply got confused. Small sharks essentially eat fish, but as they grow older they begin to see themselves as capable of “hunting” more succulent prey.
If we think about it in detail, young white sharks must not have eagle eyesight. Blind and probably color blind, the world as seen by one of these teenagers is a succession of grays one after the other. In that sense, it must not be easy to tell the difference between a succulent seal and a clueless sunbather. Over time, the sharks learn to notice the details, but in the meantime they would have to learn (by being wrong from time to time, of course).
The problem with this explanation was that, although it made sense, we had no way to ask the young sharks and our technology did not allow for easy verification. Besides, if we can clearly distinguish between a seal and a surfer, “how could sharks not?” many scientists wondered. Now, a paper published in the Journal of the Royal Society Interface has tried to pull out all the stops and simulate how these sharks see the world.
To do this, the researchers attached a GoPro to a marine “scooter” (traveling at a similar speed to the sharks) and recorded videos of sea lions, sea lions, swimmers and people on three different types of surfboards at Sydney’s Taronga Zoo aquarium. Later, they conducted numerous simulation studies in which they adjusted the resolution, color, and visual settings to match what we know about shark retinas
Their conclusions are clear: as far as they have managed to simulate, there is no significant difference between a sea lion, a person on a surfboard or even a person swimming. In other words, the fame of these sharks as killers would be somewhat unjustified: they are not the devil with fins, but rather meat-eating machines with a tendency to make mistakes.