The natural world has a new high-jump champion, with the revelation that the spittlebug can leap over 100 times higher than its body length. The feat is equivalent to a human bounding over a 70-storey skyscraper and comfortably exceeds the prowess of fleas.
The outstanding athletic ability of Philaenus spumarius, also known as the froghopper, may have evolved to help the insects escape attack from birds and other insects.
鈥淭he jumping ability of the spittlebug is incredible,鈥� says zoologist Malcolm Burrows, at Cambridge University, who conducted the study. 鈥淭he only downside is it makes them almost impossible to catch. I couldn鈥檛 believe it hadn鈥檛 been measured before.鈥�
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The spittlebug, just six millimetres long, recorded jumps as high as 700 millimetres. It has a take-off velocity of up to 3.1 metres per second, triple that of a flea. As a result the insect鈥檚 body experiences a force about 400 times that of gravity. 鈥淲hen you consider even experienced jet pilots pass out around 7g, that鈥檚 pretty impressive,鈥� Burrows told New 杏吧原创.
Stored power
There are two basic designs for jumping. Animals like the frog and kangaroo have long legs to provide leverage, allowing them to cover the same distance as short-legged animals but requiring much less force. In contrast, short-legged animals release energy they have stored in their leg muscles in order to catapult forward.
Spittlebugs have short legs, but achieve their supremacy by also using a novel leg-locking mechanism. This is required because the force needed for giant jumps cannot be produced by direct muscle contractions in the short time available.
Instead, muscular force is generated before the jump and stored. The spittlebug does this by tucking its hind legs underneath its thorax and locking them in place, using a ridge on its hind leg that engages with a protrusion on the insect鈥檚 underside.
Once the spittlebug鈥檚 muscles have generated enough force, it releases its legs and leaps skywards. The massive thoracic muscles powering the jump account for about 11 per cent of its body mass. The positioning of the muscles in the thorax means the bug can have thin, light legs, which are easily accelerated and increase the height of the jump.
The spittlebug is common in British gardens. It is best known for its ability to produce a protective froth, sometimes called cuckoo spit, and seen on blades of grass. The froth envelopes the insect and provides protection from both dessication and predators.
Journal reference: Nature (vol 424, p 509)