Now add into the equation that an octopus is an invertebrate, with no skeleton at all. Its legs have no femur, tibia or fibula, no feet and no toes to wiggle. Instead, octopuses have a hydrostatic skeleton, combining muscular contraction and water's resistance to compression to generate movement. This is very different from your own experience of moving your extremities – a little closer might be when we move our tongues, which also make use of hydrostatic pressure. Indeed, the octopus's limbs are covered in suckers that have unique sensors that taste everything they touch.
