Given a choice, sharks like to swim up on humans from behind, a new study suggests. But that's not necessarily because they're looking for lunch—they may just want to avoid trouble, say scientists at the Shark Research Institute in Florida. Their study in Animal Cognition backs up anecdotal evidence from divers and surfers that on the rare occasions when sharks attack, they tend to do so from the rear, reports the Economist. "They truly do swim up from behind, be it that they want to sneak up or they don't want to be seen," the lead researcher tells LiveScience. "It doesn't mean they sneak up in a way of having a vicious thought; mainly, they are curious but at the same time cautious."
The finding was surprising if only because researchers weren't sure that sharks would be able to differentiate, well, your front from your back. But, in a not-so-appealing job description, "research volunteers kneeled on the seafloor for hours staring straight ahead, while interactions with Caribbean reef sharks were videotaped from above," says LiveScience. Sharks approached single kneelers from the rear four times out of five. When two volunteers kneeled back to back, the sharks showed no preference.