Lead researcher Dr. Tom Matheson, a reader in Neurobiology at the University of Leicester, said the work helps explain how insects control their movements using a close interplay of neuronal control and "clever biomechanical tricks."
The study, published in the journal Current Biology, found the structure of some insect leg joints causes the legs to move even in the absence of muscles. These so-called "passive joint forces" serve to return the limb back towards a preferred resting position.
The passive movements differ in limbs that have different behavioral roles and different musculature, suggesting the joint structures are specifically adapted to complement muscle forces.
The researchers propose a motor control scheme for insect limb joints in which not all movements are driven by muscles.
"It is well known that some animals store energy in elastic muscle tendons and other structures. Such energy storage permits forces to be applied explosively to generate movements that are much more rapid than those which may be generated by muscle contractions alone," Matheson said in a statement "This is, for example, crucial when grasshoppers or fleas jump."