“I am a nice shark, not a mindless eating machine,” intones Bruce the Shark in 2003’s hit kids’ movie Finding Nemo. He is trying so hard. Unfortunately for him, according to his creators, to be a shark does pretty much consist of mindlessly, mechanistically eating things. Struggling to transcend biological destiny, poor one-dimensional Bruce is played for laughs.
It was cruel, and wrong. A study last week in Behavioral Ecology and Sociobiologysuggests that not all sharks (#notallsharks) are alike. The paper, “Shark Personalities? Repeatability of social network traits in a widely distributed predatory fish,” finds that these terrors of the deep may vary by social temperament.
Specifically, researchers discovered that some individual sharks are convivial and some are emo. Some prefer to band together into gangs, while others camouflage quietly into the background. The scientists observed 10 different groups of juvenile small spotted catsharks in large tanks that contained three different habitats. The habitats differed in their structural complexity, from a few rocks and plants to dense underwater foliage. The researchers’ aim was to observe how the teenage sharks—who, like most human high school students, are prone to feel vulnerable—interacted in environments with various amounts of cover.
And? In the words of behavioral ecologist David Jacoby, “socially well-connected [shark] individuals remain well-connected under each new habitat.” (Being well-connected when you are a catshark is a literal as well as figurative condition: It means you tend to lie on top of other catsharks, i.e. spoon.) Likewise, weirdo loner sharks isolated themselves no matter where they were, even shading their skin color to blend in better with the gravel substrate at the base of the tank. (If only I could have done that at my school dances.)
“We define personality as a repeatable behavior across time and contexts,” said Darren Croft, a professor at the Center for Research into Animal Behavior at the University of Exeter. Many animal species exhibit what scientists think of as personality traits, but Croft and his team are the first to seek out such qualities in sharks—creatures popularly viewed as uniform in their terrifying appetites, the most coolly insatiable of our underwater villains.
Of course, both the gregarious catsharks and the shy ones probably like eating fish. The second kind are just more likely to go home afterward and curl up with an old movie.
© Slate 2014
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