A pilot on board the Human Occupied Vehicle Alvin uses one of the vehicles two hydraulically-powered robotic arms to probe tube worms on the sea floor of the East Pacific Rise. The arms have clawed "hands" for deploying scientific equipment and collecting marine organisms. They have a maximum extension of 74 inches and can lift up to 150 pounds. Learn more about Alvin with the interactive feature.
(Photo courtesy of Woods Hole Oceanographic Institution)