Soft frogs
Stories from Physics
for 11-14
14-16
The tongues of frogs and toads are finely evolved to capture prey. A cane toad’s tongue can stretch by 180% during unravelling which helps the toad to pull it back as it recoils. Compared to the human tongue, which has a bulk Young’s modulus of around 300 kPa, frogs’ tongues are much softer — the tongue of the northern leopard frog has a Young’s modulus of only 4.2 kPa, so is over 70 times softer than a human tongue.
References
Soft Frogs
J. H. de Groot, & J. L. van Leeuwen, Evidence for an elastic projection mechanism in the chameleon tongue. Proceedings of the Royal Society of London. Series B: Biological Sciences, vol. 271, no. 1540, 2004, pp. 761-770.
