IBN-9511432 William Kristan To move, soft-bodied animals must first contract muscles to make themselves stiff, then contract the same or other muscles to lengthen, shorten or bend. This temporary stiffness effectively serves as a "hydroskeleton" on which the animals move. The same kind of hydroskeletons are used by tubular organs such as tentacles on an octopus, the trunk of elephants, or our own tongues and intestines. The principles underlying the control of hydroskeletons is not well-understood, largely because the arrangement of the muscles is complex and because it is very difficult to obtain all the needed physiological and mechanical measurements from a single animal or organ. These studies will use the medicinal leech to study hydroskeletons because all the relevant properties of the nervous system and muscular system can be measured in this animal. This multidisciplinary group of scientists have constructed a model of the mechanics that produces reasonable estimates of some behaviors, such as shortening and crawling. Now they will measure dynamic properties of the muscles and add them to the biomechanical model, so that faster behaviors, such as swimming, can be explained. The completed model should serve as a more general description of hydroskeletons that can be used for a better understanding of tentacles, trunks, tongues and intestines.
