Some sharks are more 'gregarious' than others and have strong social connections while others are solitary and prefer to remain inconspicuous. That's not an exception, according to a new study, these notorious predators have personality traits.

Personalities obviously exist in many animals but they are usually defined by individual characteristics such as how exploratory, bold or aggressive an individual animal is. The paper in
the journal Behavioral Ecology and Sociobiology involved testing for social personality by recording the social interactions of groups of juvenile small spotted catsharks in captivity under three different habitat types.  

The species of shark (Scyliorhinus canicula), found throughout the northeast Atlantic and Mediterranean, group together by resting around and on top of one another, sat on the bottom of the seafloor.

Working at the Marine Biological Association of the UK in Plymouth, ten groups of sharks were monitored in large tanks containing three habitats which differed in their level of structural complexity.

Dr. David Jacoby, an ecologist now at the Institute of Zoology, London said, "We found that even though the sizes of the groups forming changed, socially well-connected individuals remained well-connected under each new habitat. In other words, their social network positions were repeated through time and across different habitats.

"These results were driven by different social preferences (i.e social/antisocial individuals) that appeared to reflect different strategies for staying safe. Well-connected individuals formed conspicuous groups, while less social individuals tended to camouflage alone, matching their skin color with the color of the gravel substrate in the bottom of the tank."

Professor Darren Croft, of the Centre for Research into Animal Behaviour at the University of Exeter, added, "We define personality as a repeatable behavior across time and contexts. What is interesting is that these behaviors differ consistently among individuals. This study shows, for the first time, that individual sharks possess social personalities.

"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."