Some spotted catsharks are introverted and others are extroverted, a new study has found. Creative Commons

Some spotted catsharks are shy, others are more outgoing and some lead a solitary existence. The species of ground shark found in the shallow waters of Norway and the British Isles varies in social behavior from one individual to another, a trait that is rarely, if ever, seen in the shark kingdom, according to a new study published Thursday in the journal Behavioral Ecology and Sociobiology.

Different shark species certainly have their characteristic temperaments – it is hard to imagine the mellow whale shark ever showing aggression – however differences in personality among individual sharks of the same species are not well documented. Researchers from the University of Exeter in the U.K. found that spotted catsharks’ social personalities vary widely from one shark to the next. Some sharks liked to stay in groups, even when their physical environments changed. Others were more solitary and preferred to keep a low-profile.

These differences in behavior “appeared to reflect different strategies for staying safe,” David Jacoby, a behavioral ecologist at the Institute of Zoology who was involved with the study, said in a statement. “Well-connected individuals formed conspicuous groups, while less social individuals tended to camouflage alone, matching their skin color with the color of the gravel” in the tank.

For their experiment, researchers monitored ten groups of catsharks under three different habitat types. The habitats ranged from structurally simple to complex. They found that even as their surroundings changed, social sharks remained social and shy sharks consistently kept to themselves. “We define personality as a repeatable behavior across time and contexts,” Darren Croft, a professor in animal psychology at the university, said in a statement. “This study shows, for the first time, that individual sharks possess social personalities.”

This is not the first study, however, to show differences in personality among animals. A 2013 study from Deakin University in Melbourne found that unpredictability is a consistent behavioral trait in the animal world just like it is in humans. Some animals in a given species of fish, researchers found, were more predictable in a given context than others. They also found that some individuals chose to be more active and others chose to be more sedentary.

Another study from 2012 found similar patterns in the behavior of chimpanzees and orangutans. They measured individuals for differences in five key areas of personality: “neuroticism, extroversion, openness to experience, agreeableness and conscientiousness,” according to The BBC. Spiders, birds, mice, squid, rats and pigs have also exhibited personality differences, according to researchers in the Netherlands.