Bull Sharks Make Friends, Too
When we think about friendship dynamics, mean girl cliques or frat brothers usually come to mind. But a study published today in Animal behavior by researchers from the United Kingdom, Fiji and Switzerland reported similar friendship dynamics in groups of bull sharks (Carcharhinus leucas).
“Contrary to popular belief about sharks, our study shows that they have relatively rich and complex social lives,” Darren Croft, study author and behavioral ecologist at the University of Exeter, said in a press release.
Sharks were historically considered solitary. We now know that they hang out in groups, but gathering together doesn’t necessarily mean socializing. They could simply capitalize on the benefits of finding resources in bulk. Researchers used six years of observational data from 184 individually recognizable bull sharks in Fiji’s Shark Reef Marine Reserve to determine whether they formed social bonds, defined as “joining and remaining in a group based on social attraction to other individuals.”
Read more: “The marine biologist who dove in”
When sharks were seen swimming within a distance of each other, this was considered an “association”. When they also interacted by swimming parallel; to lead or follow; or joining or returning from another shark, these counted as “social interactions. Their sex was determined by the presence or absence of the male mating organs (clappers visible under the pelvic fins). Body size estimates were derived using a laser device and age estimates were extrapolated from existing growth data.
Overall, “association models [were] “Both males and females preferred to socialize with females (think fraternity parties). Adult sharks were responsible for most social behavior, and they preferentially associated with other adults (think not wanting to sit at the table of children). Subadults were much less social within their age group (shy adolescents) and preferred to hang out with adults (mentors).
“As humans, we cultivate a range of social relationships – from casual acquaintances to best friends, but we also actively avoid certain people – and these bull sharks do similar things,” explained lead author Natasha D. Marosi, also a researcher at the University of Exeter and founder of the Fiji Shark Lab.
As for the benefits of friendships with bull sharks, they could share knowledge, gain protection from larger individuals, or seek out future partners.
Sound familiar?
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Main image: Martin Prochazkacz / Shutterstock
