Joe Blossom/NHPA

ScienceShot: Dark Shells Make for Mean Tortoises

The next time a tortoise crosses your path, check out his shell. If it has lots of dark patches, give him a wide berth. When a team of researchers pitted two male Hermann's tortoises against each other, the one with more dark splotches on his shell was more apt to pick a fight. Heavily splotched tortoises also weren't as shy about approaching a potential predator—in this case, a human—to snatch a proffered apple, the team reports in an upcoming issue of Animal Behaviour. Color and aggressiveness may be genetically linked, the researchers say, with the same gene or set of genes coding for both traits. Or, higher amounts of the pigment melanin allow tortoises with more black shell spots to absorb extra sunlight to keep their body temperatures up, which may leave them more energy to throw into impudently defending their territory.

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