MORPHOMETRICS AND LENGTH-WEIGHT RELATIONSHIP IN THE BLUE SWIMMER CRAB, PORTUNUS PELAGICUS (LINNAEUS, 1758) (DECAPODA, BRACHYURA) FROM THE MANDAPAM COAST, INDIA

In this study, the interrelationships between various morphometric characters, viz., carapace width and length and chelar propodus length and height in males, as well as carapace width and length and abdominal width and length in females, were estimated using a total of 980 crabs, Portunus pelagicus. The carapace width/length - weight relationship was studied in both sexes on a total of 1188 crabs using the allometric growth equation of Von Bertalanffy. The allometric relationships between the characters of this set suggest that most relationships are positive and highly significant. The 'b' values for carapace width-weight in males and females were 3.607 and 3.293, respectively, and for carapace length-weight they were 3.049 and 2.774, respectively. The results show a significant deviation from an isometric growth pattern. An analysis of covariance indicates that there is a significant difference between sexes with respect to the carapace width-weight relationship.