Each individual shark has its own distinctive character, suggests a new study.
The study, published in the journal Behavioral Ecology and Sociobiology, is the first to demonstrate that the notorious predators have personality traits. The research adds to a growing body of evidence that most - if not all - creatures in the animal kingdom, from tiny insects to huge carnivores, possess unique personalities.
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"We define personality as a repeatable behavior across time and contexts," Darren Croft, of the Center for Research into Animal Behavior at the University of Exeter, said in a press release. "What is interesting is that these behaviors differ consistently among individuals."
"This study," he continued, "shows, for the first time, that individual sharks possess social personalities."
David Jacoby, a behavioral ecologist now at the Institute of Zoology, and his colleagues conducted the research.
Jacoby and his team monitored ten groups of spotted catsharks housed in large tanks. The researchers recorded the sharks' social interactions as the sharks encountered a few different habitat types set up in the tanks.
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"We found that even though the sizes of the groups forming changed, socially well-connected individuals remained well-connected under each new habitat," Jacoby said. "In other words, their social network positions were repeated through time and across different habitats."
When people are shy they are sometimes called a "wallflower" because they tend to stand alone near a wall while others cluster together to socialize. Sharks, as it turns out, do something similar.
Instead of being wallflowers, though, they are more like ‘seafloor flowers.' Jacoby explained that well-connected sharks "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."
Prior research indicates that such basic personality traits -- shy and social -- have a genetic component as well as one that is more based on experience.
The question then is: Why do personalities exist in the first place? Why aren't we all uniformly shy or social?
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Croft suspects that the differences, at least in sharks, might have emerged due to predator-prey interactions.
He said that juvenile sharks "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."