Differences in the external shape of the pleopods of Palaemon paucidens and Macrobrachium nipponense in terms of swimming ability

The oriental river prawn and the striped prawn were compared to identify characteristics of the external shape of their pleopods in terms of swimming ability. All data obtained were compared using mean values. The aspect ratio AR (length of pleopod2/area of pleopod) of the striped prawn was larger than that of the oriental river prawn. There was no difference between male and female prawns of the same species. Sexual dimorphism was found in the R ratio (ratio of seta length to pleopod length) of the striped prawn but not in the oriental river prawn. During paddling, the drag on the pleopods at the recovery stroke was relatively larger in the oriental river prawn than in that of the striped prawn. These results suggest that hydraulic efficiency during one paddling of the pleopod is greater for the striped prawn than for the oriental river prawn.