In leaps and bounds
Published: 2 January 2007 (GMT+10)
This is the pre-publication version which was subsequently revised to appear in Creation 30(4):40–41.
The amazing jumping prowess of frogs and froghoppers
Frogs must have amazing muscles to be able to jump so fast and so far, right? Actually, their leg muscles are not particularly beefy at all, leaving scientists to puzzle over how frogs can leap the way they do—easily able to jump distances more than 20 times their own length.1 (The world distance record for a single leap is 5.25 m (17½ ft) by the Mascarene rocket frog, which measures just 5 cm (2 in) from nose to tail.2,3,4) Now, it seems, researchers might have found an answer.5 They filmed bullfrogs jumping and calculated that the extra ‘spring’ needed to make such high-powered leaps must come from some elastic structure somewhere.6 So the likely explanation is that just before the frogs become airborne, their contracting leg muscles also stretch a tendon-like component. Just as the energy stored in the stretched elastic of a slingshot sends a projectile hurtling forward when released, so, too, the energy stored in the tendon helps fire a frog into the air.
Photo by B Kimmel, released under the GFDL
While a frog’s leap is impressive, research has shown that froghopper insects7(Philaenus spumarius ) should be hailed as the champion high jumpers of the world.8,9 These 6-mm– (¼-inch)–long insects can spring 70 cm (2 ft 9½ in) into the air—if it could be scaled up (notwithstanding note 1), it would be like a human jumping over a 210-metre (700-ft) skyscraper! And consider this: unlike frogs, kangaroos and crickets, which can all make use of the leverage provided by their long legs, froghoppers use their relatively short and light hind legs for jumping. So how do they do it?
While their leg muscles are indeed immensely powerful, the secret to the froghopper’s spontaneous quick-fire spring (which takes less than 1 millisecond, i.e. 1⁄1,000 of a second) is a specialized catapult mechanism that locks the legs into the cocked position until sufficient force is built up to break the lock. ‘The legs snap open and all the force is applied at once’, explained Cambridge University’s Head of Zoology, Professor Malcolm Burrows, who calculated that froghoppers exert a force up to 414 times their body weight.10
This is much higher than other jumpers such as fleas (135 times), locusts (8 times) and humans (2–3 times). Other experts in animal locomotion agree that the froghopper insect is certainly impressive. ‘It would almost make you believe in God’, said Adelaide University’s Professor Russell Baudinette, who added that the mechanism the bug uses to store the energy needed to propel itself so high is still far from understood.11
Can you imagine if people could jump like a froghopper? Actually, I don’t think anyone of human size would want to jump like a froghopper—or even a frog, for that matter. Because it’s one thing to leap … but it’s quite another to land! Yet frogs and froghoppers can quite safely do both12—so, here’s one jump that we can make. We can jump to the obvious conclusion that their remarkable abilities are surely evidence of a Designer! ‘For since the creation of the world God’s invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that men are without excuse’ (Romans 1:20).
- Note that that relative length or height is something of a red herring, because the physics would predict that animals should be able to jump roughly the same absolute length or height. This is because strength or force is proportional to mass, but the acceleration is inversely proportional to mass, and the two cancel. So, mathematically, it is not such a surprise that a flea should be able to jump to about the same absolute height (within an order of magnitude) as a man. However, this doesn’t negate at all the amazing design of their jumping machinery. Return to text.
- J. and Schmidt, L., Reptiles and Amphibians—A thematic unit, Utah State University, 6 October 2003. Return to text.
- Mascarene rocket frog, Ptychadena mascareniensis, 6 October 2003. Return to text.
- Olympic athletes can only jump around five times their body length—and that’s from a running, not stationary, leap. The men’s long jump world record is 8.95 m (29 ft 4.5 in). (The high jump record is 2.45 m (8 ft 0.25 in).) Return to text.
- Frogs get energy boost to leap long and high, New Scientist 179(2403):20, 2003. Return to text.
- Roberts, T.J. and Marsh R.L., Probing the limits to muscle-powered accelerations: lessons from jumping bullfrogs, The Journal of Experimental Biology 206(15):2567–2580, 2003. Return to text.
- Also known as ‘spittle bugs’—a reference to the froth (blown out of their back ends) which covers the developing young. Return to text.
- Burrows, M., Froghopper insects leap to new heights, Nature 424(6948):509, 2003. Return to text.
- Record jumper, New Scientist 179(2406):20, 2003. Return to text.
- Amos, J., Garden insect is jump champion, BBC News Online, 2 September 2003. Return to text.
- Macey, R., Super bug way ahead in leaps and bounds, Sydney Morning Herald, 31 July 2003, p. 3. Return to text.
- Physically, there is an explanation. If you were scaled down to 1/10 of your height, your surface area would be 1/100 but your mass would be only 1/1000. Air resistance depends on area while gravity on mass, so the ratio of air resistance to gravity would be far greater. Because of this natural ‘parachuting’ effect, you would have a much lower terminal velocity, or the maximum speed you can reach in free-fall. So it is not surprising that small animals can easily survive falls that would kill a man. Return to text.