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Blue crab Bardawil Lagoon Feeding habits Gastric mill Stomach contents of 161 specimens of Callinectes sapidus(Crustacea: Decapoda: Portunidae)from Bardawil Lagoon were examined from November 2016 to July 2017. The percentage point (% P) and percentage frequency of occurrence (% F) methods were used for stomach contents analysis. Out of the 161 individuals 75 (46.58 %) had empty stomach. Mollusca, Crustacea and Pisces dominated the diet of this species. According to points method Mollusca, Crustacea and Pisces scored 44.83%, 18.1% and 16.24% points in malesand 47.2%, 21.62% and 11.03% points in females, respectively. Consumed tissues of other benthic invertebrates were also present in verylow ratios, while algal fragments were occurred in low quantitiesin few stomachs. Sediments were also detected in considerable ratios. Results of the present study suggest that the blue crab C. sapidusis a carnivore. The remarkable seasonal fluctuations in the diet composition and stomach fullness of this species during the present studywere detected For understanding the mechanism of feeding, gastric mill structure was morphologically investigated and all its seven articulated ossicles were examined and photographically illustrated.

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D uring the present study, the stomach contents of a medium-sized grapsid crab, Metopograpsus messor (Grapsidae, Brachyura) inhabiting different habitats (rocky, sandy-rock, and mangrove swamps) of the Red Sea (southern Aqaba Gulf) were examined by both frequency occurrence and percentage points. The results show that this species is opportunistic omnivore, with general food items consisting of algae (brown, red, green and blue green), benthic animals dominated by crustacean copepods, isopods, amphipods and other crustaceans,. in addition to foraminiferans, polychaetes and animal eggs, with few fragments of hydroids, bryzoans as well as organic debris and unidentified items. Higher plants including leaves and adventious roots of mangroves and seagrass leaves were also reported among stomach contents. Moreover, sediments were represented by considerable amounts at both different habitats and seasons. The types of foods were significantly different through various habitats and seasons.The gastric mill of the crab, which deals mainly with mechanical digestion was investigated by both light and scanning electron microscopes. It appeared as a very complex structure, composed of 6 240

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