1 . Many of us think of sharks as powerful, mysterious, and lonely as they move through the deep. And nowonder the fish have long been portrayed in popular media as lone predators, appearing out of nowhere to attack. But that image has come under inspection in recent years, as shark researchers around the world have discovered the fish gathering in large numbers and interacting with others of their own species in ways that are obviously friendly.

Yannis Papastamatiou, a marine scientist at Florida International University, and his team used acoustic transmitters to record the interactions over four years of about 40 reef sharks around Hawaii. Their study found that reef sharks return to the same communities year after year, forming clear preferences for sharks with some friendships that endured throughout the study. In his 2016 study, he found that individual sharks tagged with recording devices had thousands of interactions with their peers, with some pairs spending up to four straight days together. The study also found certain sharks were unmistakably companions. “These weren’t random associations,” he says.

Finding out why sharks socialize — and how much of their behavior is cooperative — is a challenge, but there are some clues, such as food availability and warmer waters. Great white sharks, are showing up in record numbers along southern California beaches as the population has doubled since 1994. While great white sharks typically maintain distances of about 30 feet from each other and don’t seem too close, they are clearly drawn together by a preference for the area. In some cases, there may not be an obvious purpose for shark’s friendship. At the Bimini Shark Lab, Smukall and his colleagues found that young lemon sharks sought out companionship of other sharks for no clear reason. There’s growing evidence that lemon sharks have their own personalities, which may influence whether they spend time with other sharks, he adds.

More would be known about the intimate lives of sharks if the field weren’t so new, due in part to a lack of funding and sharks’ negative reputation. “We’ve only had about 20 years to really start studying sharks,” says Smukall.