Hind Legs Amplify Power

a long insect with a tan body and black spots and long wings stands on sand

Biological Strategy

Desert locust

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Store Energy

Once a living system captures energy or transforms one energy form into another, it must frequently save that energy for future use. But energy is difficult to store in some forms. So living systems need strategies to either use energy quickly, or to convert it from forms that are difficult to store (such as electrical or kinetic) to more storable forms. For example, grasshoppers store energy as potential energy in an elastic material in their tendons. When they need to jump, that energy converts into kinetic energy, providing the force needed to escape predators.

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Transform Mechanical Energy

Mechanical energy is made up of kinetic energy (the energy of an object in motion) and potential energy (stored energy). Organisms use mechanical energy in a variety of ways, including capturing prey, transporting seeds, and moving around.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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The hind legs of the locust amplify jumping power via energy stored in muscle attachment sites.

“And that’s where energy storage comes in. Down to the size of a trout or a squid tentacle, unaided muscle can do a decent job with nothing more than ordinary leverage. Below that, muscle needs help; in practice, energy is put in slowly and stored elastically. Some kind of trigger then releases it at a higher rate. Work and energy may be conserved, but power gets amplified… A locust or grasshopper jumping with its hindlegs stores up work in chitinous apodemes and gets a tenfold power amplification (Bennet-Clark 1975)… Each of these creatures has some kind of a mechanical catch to prevent premature extension while the work is being put in; the specific arrangements, though, are different for each case.” (Vogel 2003:476)

Last Updated August 18, 2016

References

Book

Comparative Biomechanics: Life's Physical World, Second Edition

17/06/2013 | Steven Vogel

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Reference

Journal article

The energetics of the jump of the locust Schistocerca gregaria.

Journal of Experimental Biology | 01/08/1975 | Bennet-Clark, HC

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