Octopus arms a good model for robot designs
9 February 2005, National Geographic News

Octopuses have intrigued scientists for years; because they have both long-and-short term memory, they remember solutions to problems, and they can go on to solve the same or similar problems. They have been known to climb aboard fishing boats and open holds in search of crabs. They can figure out mazes, open jars, and break out of their aquariums in search of food.

The arms are composed almost entirely of muscle, with no bone or external skeleton-a structure known as muscular hydrostat. Earlier research suggests that to keep the arms from constantly tangling themselves up, each arm has an independent peripheral nervous system and neural circuitry. This allows the brain to essentially give a command-arm four, get that tasty crab crawling by-and have the arm carry out the order without the brain thinking about it again. This ability is combined with excellent eyesight. Once it spots it prey, it reaches out with one of its arms and grabs it with one of the suckers that form a double line up on each of the octopus's arms. To bring the captured food to its mouth, the octopus turns the arm into a semi-rigid structure that bends to form quasi joints. Just as a human arm has joints at the shoulder, elbow and wrist that allow our arms to bend and rotate. Understanding how the octopus controls eight flexible arms might lead to the perfect robotic arm design.