Jumping in Drosophila

Flies jump about 30 mm by using a thoracic muscle (TDT) to move their legs. Film by Trimarchi & Scneidermann is here

This muscle is activated by a giant fiber which runs from the brain to the thorax. The first figure, shows a video of the leg moving when the giant fiber is stimulated electrically.

Video: Normal speed
(100 frames/sec,
156k Bytes)
Slowed down  10 times
(10 frames/sec,
156 kBytes)

To measure the force used to make the fly jump we built a force platform from a small strain gauge, and made the fly kick down onto this by attaching a glass needle between fly and force platform

Force transducer
Sensor for fly muscle force
Fly clamped and fixed to needle
Fly fixed to sensor

The measurements show the fly generates a peak force abou 20 times its own weight, so that it can jump upwards easily. The force
calculated  from the jumping distances matches well with that measured in our apparatus.

Details are available form a poster shown at Neurofly 2004, or from a paper published in The Journal of experimental Biology (York copy)

Chris Elliott, 10 Sept 2004