Sharks with a Personality: Small Catsharks Can be Gregarious or Less Social

Most pet owners realize that different dogs and cats have different personalities. But did you know that sharks also vary when it comes to social interactions? Scientists have found that while some sharks are gregarious and seek out social connections, others are more solitary.

In animals, personalities are usually defined by individual characteristics, such as how exploratory, bold or aggressive an animal is. In order to find out whether sharks can display these differing traits, the researchers recorded the social interactions of juvenile small spotted catsharks in captivity under three different habitat types.

These sharks can be found throughout the northeast Atlantic and Mediterranean. Usually, they group together by resting on top of one another while resting on the bottom of the seafloor. In this case, the scientists examined how the sharks grouped together in different habitats.

"We found that even though the sizes of the groups forming changed, socially well-connected individuals remained well-connected under each new habitat," said David Jacoby, one of the researchers, in a news release. "In other words, their social network positions were repeated through time and across different habitats."

In fact, the researchers found that the choices the sharks made were driven by different social preferences-social and antisocial individuals. Well-connected individuals formed large groups while less social individuals preferred to camouflage alone and match their skin color with the color of the gravel substrate at the bottom of the tank.

"We define personality as a repeatable behavior across time and contests. What is interesting is that these behaviors differ consistently among individuals. This study shows, for the first time, that individual sharks possess social personalities," said Darren Croft, one of the researchers. "In the wild these small juveniles can make easy prey items for larger fish, so different anti-predator strategies are likely to have evolved. More research, however, is required to truly test the influence of predators on social personality traits in sharks. This study is the first step in that direction."

The findings are published in the journal Behavioral Ecology and Sociobiology.