Crocodilians - alligators and crocodiles - deserve their reputation as fearsome predators, taking on prey that most other animals would leave alone. Once they have a victim grasped in their jaws, however, they have a problem. Although their conical teeth are perfect for grabbing food, they're pretty useless for tearing it up. So crocodilians developed the `death-roll', a fearsome spinning manoeuvre which they use to subdue and dismember their prey. Interested to know how alligators perform the death-roll, Frank Fish and his colleagues filmed juvenile alligators spinning in a tank holding onto tasty meat morsels with their jaws (p. 2811). To spin, an alligator presses its limbs against its body and bends its head and tail relative to its body, forming a C-shape. After the turn, it straightens itself out again and splays its legs to stop turning. By mathematically modelling the death roll, the team calculated that the baby alligators generate shear forces of 0.015 N, but these forces disproportionately increase to 138 N when scaled up to a ferocious 3 m alligator, allowing them to tear up and dine on ever larger prey.

Fish, F. E., Bostic, S. A., Nicastro, A. J. and Beneski, J. T. (
2007
). Death roll of the alligator: mechanics of twist feeding in water.
J. Exp. Biol.
210
,
2811
-2818.
© The Company of Biologists Limited 2007
2007