Feeding, temporal, and spatial preferences of Metopograpsus thukuhar (Decapoda; Grapsidae): An opportunistic mangrove dweller

Metopograpsus thukuhar is a very common grapsid in the Indo-Pacific mangrov es but is found only occasionally in a non-mangrove environment. Field obse rvations investigated its spatial and temporal strategies and clarified its predatory abilities. Gut-content analysis was used to assess its natural d iet. Metopograpsus thukuhar was mainly active during low tide. although man y crabs were seen at high tide moving on the mangrove roots above the water level. It lived largely among the roots of the seaward Rhizophora mucronat a and concentrated its activity within a definite area of the root apparatu s of a single tree, appearing to be faithful to one or two specific crevice s. The diet of M. thukuhar was principally based on macroalgae; mangrove le aves were also present, but animal items were rare. However, direct held ob servations of the crab's predatory behavior indicate that this grapsid is a n opportunistic feeder with a certain degree of behavioral plasticity.