A unique form of locomotion in a stomatopod—backward somersaulting

Abstract

Of the diversity of forms of locomotion evolved by life on Earth, one that seems not to have developed to any great extent is rolling or somersaulting. Many cultures claim the existence of ‘hoop snakes’ that grasp their tails in their mouths and roll downhill, but no known snake can perform this feat1. Furthermore, although at least one spider (Hamilton, personal communication) when disturbed forms its body and legs into a sphere and rolls down sand dunes, I have been unable to find examples of animals that roll uphill or even over level terrain. Various coelenterates such as Hydra and some sea anemones somersault slowly across the substrate by alternating attachment of the pedal disk and tentacles. However, with the exception of human gymnasts and other playful primates, I report here a unique form of locomotion found in the stomatopod Nannosquilla decemspinosa (Rathbun, 1910) that consists of a rapid series of backward somersaults.