small spotted catshark
October 4, 2014

Researchers Find That Sharks Have Personality

April Flowers for - Your Universe Online

We know that our pets have strong personalities because we observe them every day. But who would have guessed that sharks have different personalities as well.

A new study, led by the University of Exeter and the Marine Biological Association of the UK (MBA), reveals that some sharks are “gregarious,” with strong social connections, while other species of shark are shy and prefer to remain unnoticed.

Most animal personalities can be divided into categories such as how bold, aggressive, or curious an animal is. The findings, published in Behavioral Ecology and Sociobiology, represent the first time research has been able to show that individual sharks have social personalities which might determine how they interact with group mates in the wild.

The team, which included Dr. David Jacoby of the Institute of Zoology, London, tested groups of juvenile small spotted catsharks (Scyliorhinus canicula) in captivity under three different habitat types by recording the social interactions of the individuals to assess social personality. Spotted catsharks are found throughout the northeast Atlantic and Mediterranean. They tend to rest around and on top of each other on the bottom of the seafloor.

According to Jonathan Webb of BBC News, ten groups of ten sharks were studied in three different situations in large tanks at the MBA in Plymouth, UK. Some of the environments were complex, with a large number of rocks and other features. Other environments were simple tanks with only gravel on the bottom.

Despite the change in environments, the overall number of sharks in a tank, or the number of sharks in any one sub-group, individual sharks that tended to form groups continued to do so. More antisocial individuals also remained antisocial, or in smaller social groups.

"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,” Jacoby said in a recent statement.

"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 Behavior 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 a similar, but unrelated study, a group of scientists led by the University of Lincoln’s Dr. Anna Wilkinson reveal that reptiles engage in social imitation; they learn by watching others, reports David Freeman for the Huffington Post . Prior to this study , published in the journal Animal Cognition, only humans and certain other primates were thought to use social imitation.

According to the Freeman, the researchers set up a simple experiment using a dozen bearded dragons and a wooden board with a sliding wire door. Eight bearded dragons were allowed to watch a demonstrator lizard that had been trained to use the door to get a treat — a fat, juicy mealworm. The remaining four bearded dragons did not have a demonstrator.

All eight of the observing reptiles were able to work the door, while none of the control group learned how.

"This research suggests that the bearded dragon is capable of social learning that cannot be explained by simple mechanisms--such as an individual being drawn to a certain location because they observed another in that location or through observational learning," said Wilkinson of the University of Lincoln's School of Life Sciences in England. "The finding is not compatible with the claim that only humans, and to a lesser extent great apes, are able to imitate."