Pauropoda are soft, cylindrical animals with bodies 0.5 to 2 millimetres (0.02 to 0.08 in) long.[1] The first instar has three pairs of legs, but that number increases with each moult so that adult species may have 9 to 11 pairs of legs. They have neither eyes nor hearts. The body segments have ventral tracheal/spiracular pouches forming apodemes similar to those in millipedes and Symphyla, although the trachea usually connected to these structures are absent in most species.[2] The antennae are branching, which is distinctive for the group.[3]