Many of us think of sharks as powerful, mysterious, and solitary as they glide through the deep. And no wonder, since the fish have long been portrayed in popular media as lone predators, appearing out of nowhere to attack.

But that image has come under scrutiny in recent years, as shark researchers around the world have discovered the fish congregating in large numbers and interacting with others of their own species in ways that are decidedly friendly.

Their study, published in 2020 in the journal Proceedings of the Royal Society B, found that reef sharks return to the same communities year after year, forming clear preferences for the company of certain other individuals, with some “friendships” that endured