The pereiopods include chemoreceptor cells, which are sensitive to aqueous extracts of food and to salts (and may therefore be involved in migratory and reproductive processes). The left and right second legs (chelipeds) of M. rosenbergii are equal in size, unlike some other Macrobrachium spp. In adult males they become extremely long and reach well beyond the tip of the rostrum..
The tail (abdomen) is very clearly divided into 6 segments, each bearing a pair of appendages known as pleopods or swimmerets (as this name implies, they are used for swimming, in contrast to the walking legs). The first five pairs of swimmerets are soft. In females they have attachment sites for holding clusters of eggs within the brood chamber (see below). In males, the second pair of swimmerets is modified for use in copulation. This spinous projection is known as the appendix masculina. The sixth pair of swimmerets, known as uropods, are stiff and hard. The telson is a central appendage on the last segment and has a broad point with two small spines which project further behind the point. The telson and the uropods form the tail fan, which can be used to move the prawn suddenly backwards.