Stories and videos of the attacks widely shared on social media have turned the orca into a meme. After the marine mammals struck some fancy yachts, some observers are calling the strikes concentrated around the Strait of Gibraltar, where the whales congregate in the spring and summer, an act of anti-capitalist solidarity from “orca comrades” and “orca saboteurs.” For others, the series of strikes is eerily similar to a scene in James Cameron’s latest “Avatar” movie, “The Way of the Water.”

So what is happening? The scientists studying the whales themselves aren’t entirely sure, either. But they have two leading ideas:

Theory No. 1: The orcas are playing around

Closely related to bottlenose dolphins, orcas are highly intelligent and curious marine mammals. Using a series of underwater pulses and whistles, the whales communicate with such sophistication that pods form their own dialects and parents teach their young hunting methods that are passed along for generations.

After learning a new behavior, juvenile orcas often keep repeating it ad nauseam. (In that way, they are a lot like human youngsters.) Playing around is just a part of learning how to be an apex predator.

That matches the pattern of attacks whale scientists have witnessed this year, according to Alfredo López Fernandez, a researcher at the University of Aveiro in Portugal working with GTOA.

In this case, the behavior is “self-induced,” López Fernandez said, and not caused directly by some outside (i.e., human) provocation. “Which means that they invent something new and repeat it,” he added.

But there’s another potential motivation that sounds straight out of “Moby Dick.”

Theory No. 2: The orcas want vengeance

Orcas off the Iberian Coast like to follow fishing vessels to snag bluefin tuna before fishermen can reel them in, putting the aquatic mammals at risk of being struck or entangled. Scientists have seen killer whales in those waters with fishing lines hanging from their bodies.

So it is possible, López Fernandez said, an orca had a bad run-in with a boat in the past, and is now teaching other killer whales how to attack vessels as well. The team suspects a female adult named White Gladis may be the one doing so.

López Fernandez emphasized we don’t have enough information to know the real reason behind the attacks yet. Even assuming the second theory is true, “we don’t know what that triggering stimulus could have been,” he said.

With only 39 orcas counted in 2011, the Iberian orca subpopulation is considered critically endangered by the International Union for Conservation of Nature. The impact that entanglements and boat strikes are having on all sorts of whales and dolphins around the world underscores that humans are a bigger threat to them than they are to us.

“All this has to make us reflect on the fact that human activities, even in an indirect way, are at the origin of this behavior,” López Fernandez said.