Portunus pelagicus were obtained from a shallow coastal area in the Kingdom of Bahrain, Arabian Gulf (26 14 909 N and 50 297 121 E) during the years 2004 and 2005 using local fish trap on sandy mud or sand substrates. Different body measurements were carried out including fresh body weight, carapace width carapace length, total length and width of both right and left chelae, and abdominal length and width for both sexes. The measurement also included cheliped’s maximum span, the length of different segments of both right and left dactylus, propodus, carpus and merus. Results indicate linear regression relationships (positive allometric growth) of different body dimensions relative to the body weight and carapace width. Compared to females, males are not just heavier but also have larger body dimensions. Abdomen width and length grow as the body size increases in both sexes. Higher positive allometric growth of the abdominal width observed in females was related to the female reproductive role in carrying the egg mass. Slightly longer abdominal flap in the case of males was also noted. Greater positive cheliped allometric growth in male crabs was discussed in terms of possible sexual dimorphism. The occurrence of heterochely, and slight right-handedness observed in both sexes was unexpected in a swimmer crabs such as P. pelagicus. © 2016, King Fahd University of Petroleum & Minerals.

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