MARY LOUISE KELLY, HOST:
Sharks are often portrayed as Hollywood monsters - lone wolves in search of prey.
ARI SHAPIRO, HOST:
But a new study provides more evidence that some sharks can be social and stick together in large groups.
YANNIS PAPASTAMATIOU: They form these sort of spatially structured social groups where they hang out with the same individuals over multiple years.
KELLY: Yannis Papastamatiou runs the Predator Ecology and Conservation Lab at Florida International University. His team studied grey reef sharks at an atoll in the central Pacific.
SHAPIRO: They tagged 41 of the animals with location transmitters and outfitted several sharks with little video cameras on their fins.
PAPASTAMATIOU: So we're really getting a shark-eye view of what they're doing. What we were seeing was group sizes of about 20 individuals.
KELLY: And what they found - some of the social groups persisted the entire length of the study, up to four years. That is longer than previous studies have observed.
SHAPIRO: David Shiffman studies shark ecology and conservation at Arizona State University, and he says he was pretty surprised by the news.
DAVID SHIFFMAN: The groupings stayed pretty stable. The same individuals hang out together not only day after day, but year after year. I mean, I don't have a lot of friends that I do that with.
KELLY: Now as for why the sharks form these cliques, Papastamatiou says social groups might boost the hunting success of everybody involved.
PAPASTAMATIOU: If we hang out together and I see something, then you can come and try and take advantage of that. And alternatively, if you see something, then I can try and take advantage of that.
SHAPIRO: He says these tips from friends could be one factor that helped shark society evolve. And it's a more complex community than we thought, more akin to that of birds or even mammals. The details are in the Proceedings of the Royal Society B.
KELLY: And just as these sharks might learn where dinner is by congregating with their peers, Shiffman says the social abilities of sharks do not stop there.
SHIFFMAN: An individual shark can be taught to solve a simple puzzle, and another shark can solve that puzzle just by watching the first shark do it.
KELLY: He says, maybe it's time to lose our prejudices about sharks.
SHIFFMAN: It turns out they're a lot smarter than most people think. And they have more complex social behaviors and more complex abilities to process their environment and learn and change.
SHAPIRO: As for what to call a group of sharks, well, the name still evokes fear. It's known as a shiver of sharks.
(SOUNDBITE OF SVEN LIBAEK'S "ATTACKING SHARKS") Transcript provided by NPR, Copyright NPR.