SHARK BODY LANGUAGE: TAKING TURNS

Sickle-fin lemon sharks, close relatives of lemon sharks from the Indo-Pacific, have been studied for a decade in French Polynesia. Using cameras set up around a bait box, scientists recently discovered that they formed a pecking order based, surprisingly, not on body size but the shark’s behaviour. “Every shark in the group had a very precise position in the hierarchy,” says Pierpaolo Brena, the study leader. Higher-ranking sharks that got to eat first were less submissive and tended not to veer off when swimming towards others. “To our knowledge, it’s the first time that adult, free-ranging sharks have been shown to adapt to the behaviour of their rivals,” Brena says.