Abstract: Size at sexual maturity and patterns of somatic growth are important aspects of
reproductive history of crab. The main purpose of this study is to provide an estimate for the onset
of morphological sexual maturity in mangrove crab, Opusia indica from a population located in
Korangi creek intertidal mud flat (Karachi, Pakistan) based on relative growth. The crabs were
monthly collected through quadrat method from March 2001 to February 2002. A total of 1702 crabs
was obtained, of which 764 were males, 939 were female. The morphometric measurement of
carapace, abdomen, cheliped and male gonopod was related to carapace width. Based on carapace
width males were significantly larger than female, indicating sexual dimorphism. The size at onset
of sexual maturity in males was estimated as 5.51 mm carapace width and 5.3 mm carapace width in
females. The positive allometric growth of female abdominal width were likely related to the
incubation process.
Article history:
Received 7 July 2016
Accepted 8 August 2016
Available online 25 August 2016
Keywords:
Sexual maturity
Somatic growth
Intertidal
Morphometry
Allometry