Ovigerous females of Arenaeus cribrarius were collected at Ubatuba, São Paulo, and maintaining in aquaria under controlled temperature (25±1ºC), salinity (35±1‰) and photoperiod (12:12). A small sample of eggs was collected for each 24h, for morphological description, chromatic changes and biometric analysis throughout the embryonic development. Eight egg stages were photographed and had their small and large diameters measured under a microscope provided with camera lucida. The egg's shape was low elliptical during all the embryogenesis and showed size increase (24.4%) and volume (91.1 %), when the last stage were compared with the first one. According to mean egg diameter and volume, the eggs should be pooled in three different groups (1-3; 4-6; 7-8) corresponding to initial, intermediate and final stages. The attained results were compared with the literature which emphasizing the species of Portunidae's family.
Crustacea; Brachyura; Portunidae; swimming crab; embryology