The size and shape of a tortoise's shell influence how quickly the animal can right itself when it falls onto its back.

Ana Golubović of the University of Belgrade and her colleagues studied the Hermann's tortoise (Testudo hermanni; pictured), which lives in hilly, rocky habitats that often flips the animal onto its back. The team measured the amount of time it took adult male and female tortoises to get back on their feet after being turned over.

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They found that larger animals of both sexes spent more time righting themselves than smaller ones. Males that had larger plates along the rear edge of their shell — useful for adding stability during mating — also took longer to flip themselves back over.

A similar effect of shell shape on flipping may be found across other tortoise species, the researchers say.

Zool. Anz. 254, 99–105 (2015)