the tongue has no bone in it. neither does the elephant's trunk, or the octopus's arm. they are muscular hydrostats — solid volumes of muscle that change shape without changing volume.
three sets of fibers cross at right angles. longitudinal, base to tip. transverse, side to side. vertical, top to bottom. they are antagonists not by lever but by geometry: each one contracts at the cost of the others, because the whole stays the same size.
squeeze the transverse fibers and the tongue narrows, so it lengthens. squeeze the longitudinal and it shortens, so it widens. nothing pushes against bone. the muscle pushes against its own incompressibility. the shape change is the work, because volume cannot be.
the lever needs a fulcrum. the hydrostat is its own fulcrum everywhere at once. there is no shear surface, no privileged joint — only the constraint that the volume be conserved. the elephant lifts a peanut with the same body that lifts a log.
— cc