The majority of our knowledge about how animals move is based on creatures that walk, fly or swim using rigid articulated bones and exoskeletons. However, animals without backbones (invertebrates) are the most numerous animals on the planet and nearly all are soft-bodied (with hydrostatic skeletons) for at least part of their life. These crawling creatures do not escape predators by running but instead use camouflage, chemical defenses and cryptic behavior. As a consequence, crawling has evolved into a highly specialized form of locomotion which allows soft-bodied animals to move in complex and confined three-dimensional structures such as tubes and branches.

     With a soft-body, joints do not restrict movements. Such animals can crumple, compress and rotate body parts with virtually unlimited freedom. Such complex movements are very interesting from a neural control perspective because movement coordination by the nervous system has co-evolved with these biomechanical features.

     These new studies use a caterpillar, the tobacco hornworm, Manduca sexta, as a model system to help understand the neural control of hydrostatic movements. Two specific aspects are being examined in detail: first we are trying to understand how crawling is controlled by the central nervous system and how it interacts with peripheral structures such as muscles and cuticle; secondly, we are interested in the unique ability of caterpillars to climb using curved hooks at the tips of the abdominal prolegs. This gripping is passive but very strong (like Velcro hooks) and can be actively released. We will determine how this gripping is controlled and how it is integrated into normal crawling.

     Although focused on understanding animal locomotion, these studies have potential applications in the design and control of a new type of flexible robot. Such robots could be used to navigate through pipelines or intricate structures such as blood vessels and air tubes. Finally, in examining the mechanism of proleg gripping it is possible that new adhesive materials could be developed that attach passively but can be released actively to avoid the tearing forces in conventional hook and loop fastenings.

     To examine these questions we use 3D kinematics, electromyography, hydraulic measurements, magnetic resonance imaging, 3D modeling and animation, biomaterials testing and muscle work loop analysis.

For more details and movies of soft-bodied motion-capture click on the picture (this page contains several movies and could be slow to load in older browsers or over slow connections)