Morphological Study in Zoeal Stages of Mud Crabs: Scylla olivacea (Herbst, 1796)

Abstract

The larva of mud crab, Scylla olivacea consisted of five zoeal stages. These zoeal stages were illustrated on the basis of laboratory culture from three ovigerous females. The appendage such as mandible, maxillule, maxilla including antennule, antenna, maxilliped and telson were described showing the difference among the zoeal stages. In the first zoeae, the presence of the sessile eyes and 3 pairs of setae at the telson were used to distinguish from the other zoeal stages. From the second through the fifth zoeal stages, the number of setation on maxillule, maxilla, first and second maxilliped were used to discriminate among these zoeal stages. The more advanced zoeal stages, the more number of setation on these appendages. From the second through the fifth zoeae, the setae on basal endite of maxillule and maxilla were 8, 9, 12, 14 and 9, 10, 12, 16 setae, respectively. The setae on the exopod of the first and second maxilliped were 6, 8, 10, 12-15 and 6, 9, 11-12, 14-16 setae, respectively. For the fifth zoeae, the presence of biramous pleopod on the second to the fifth segment was the key character to distinguish from the other zoeal stages. The zoeal morphology of Scylla olivacea from this study were compared with those of Scylla serrata.