Octopus arms work in a similar way to an elephant’s trunk, a snail’s foot and your tongue. Known as ‘muscular hydrostats’, these structures consist almost entirely of densely packed muscles.
By combining in different arrangements, the muscles can provide an impressive range of movement. When octopuses crawl along the seabed, they contract lengthwise and crosswise muscles in their arms, elongating and shortening their arms in turn. They twist their arms by contracting sets of muscle fibres that wrap diagonally around them.