Sharks Have Distinct Personalities to Go Along With Their Unwavering Bloodlust

It's difficult to imagine the shark from Jaws having any personality beyond an Anton Chigurh-like thirst for man-hunting. But according to new research, real sharks have a range of personalities ranging from shy loner to gregarious social butterfish.

The study, published today in Behavioral Ecology and Sociobiology by researchers at the University of Exeter and the Marine Biological Association of the UK, is the first to demonstrate that individual sharks have unique temperaments and preferences.

Testing shark personalities seems like a tricky endeavor—it's not like you can slip a Briggs-Meyer test in with the chum. Instead, the Exeter team selected small-spotted catsharks as their guinea pigs for the experiment. At under a meter in length, they are a lot less risky than their larger, toothier brethren. They are also popular aquarium fish, so they could be studied easily in captivity.

To root out the popular crowd from the loners, the Exeter team exposed the catsharks to several different environments and social groupings, monitoring the reactions of individual sharks in each instance. Lo and behold, some sharks were always social, while others were consistently shy, preferring to hang out on the fringes of their tanks.

"We found that even though the sizes of the groups forming changed, socially well-connected individuals remained well-connected under each new habitat," explained co-author David Jacoby in a University of Exeter statement. "In other words, their social network positions were repeated through time and across different habitats."

Though the Exeter team is the first to produce solid conclusions, PhD student Jean-Sebastien Finger of Humboldt University has also published preliminary research into shark personalities. Finger's team used juvenile lemon sharks in his study, which are roughly the same size as adult catsharks. But the main difference between the two studies was that Finger studied wild sharks instead of ones in captivity.

Both teams noted how social individual sharks were in a group, but Finger also monitored how bold each shark was when confined in a tank with no companions. His team then tagged and released the sharks, only to recapture the same individuals six months later in order to repeat the tests for consistency.

Interestingly, Finger's team found that the shy sharks were more likely to explore their tanks alone, while the gregarious sharks didn't venture out much when isolated. Perhaps these behaviors, as well as those observed by the Exeter team, reflect different survival strategies in the wild.

The loner sharks may not have a pack to back them up, but in exchange, they develop independence and curiosity. The popular sharks, on the other hand, have a "safety in numbers" approach when exploring the great unknown.

"Well-connected individuals formed conspicuous groups, while less social individuals tended to camouflage alone, matching their skin colour with the colour of the gravel substrate in the bottom of the tank," said Jacoby of the Exeter study.

Sharks are far from the first animals that have been shown to have distinct personalities. Heck, even ants have a sort of hivemind personality.

The larger mystery inherent in these studies is why personalities seem to be so intrinsic to the survival of so many species, and whether expression of these temperaments is similar across such diverse clades. And there's only one way to find out: By voyeuristically observing the behavior of a lot more animals. Get on it, biologists.