A new study, led by Dr David Jacoby of the Institute of Zoology in London, UK, has shown for the first time that the fearsome predators of the deep blue sea have personality traits.
The Small-spotted catsharks (Scyliorhinus canicula). Image credit: Thomas Ernst / CC BY-SA 2.5.
Personalities are known to exist in many animals, but are usually defined by individual characteristics such as how exploratory, bold or aggressive an individual is.
The new study, published in the journal Behavioral Ecology and Sociobiology, is the first to show that individual sharks possess social personalities.
“Some sharks are gregarious and have strong social connections, whilst others are more solitary and prefer to remain inconspicuous,” Dr Jacoby and his colleagues said.
To reach their conclusions, the researchers recorded the social interactions of captive groups of juvenile Small-spotted catsharks (Scyliorhinus canicula) – a species found throughout the northeast Atlantic and Mediterranean.
Ten groups of catsharks were monitored in tanks containing three habitats which differed in their level of structural complexity.
“We found that even though the sizes of the groups forming changed, socially well-connected individuals remained well-connected under each new habitat,” Dr Jacoby said.
“In other words, their social network positions were repeated through time and across different habitats.”
Dr Jacoby said: “these results were driven by different social preferences 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.”
Prof Darren Croft of the University of Exeter, UK, who is the senior author on the study, 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.”
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David M. P. Jacoby et al. Shark personalities? Repeatability of social network traits in a widely distributed predatory fish. Behavioral Ecology and Sociobiology, published online October 02, 2014; doi: 10.1007/s00265-014-1805-9
