Minimal design of the elephant trunk as an active filament

One of the key problems in active materials is the control of shape through actuation. A fascinating
example of such control is the elephant trunk, a long, muscular, and extremely dexterous organ with
multiple vital functions. The elephant trunk is an object of fascination for biologists, physicists, and
children alike. Its versatility relies on the intricate interplay of multiple unique physical mechanisms
and biological design principles. Here we explore these principles using the theory of active filaments
and build, theoretically, computationally, and experimentally, a minimal model that explains and
accomplishes some of the spectacular features of the elephant trunk.