الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Mantis shrimp and crabs are edibles crustaceans and very abundant but they don’t get adequate attention in the research and industrial fields. They are considered as a source of chitin and chitosan. So, this study focused on identifying the crustacean as E. massavensis from the coast of the Egyptian Mediterranean Sea and C. natator from the Red Sea, Egypt. It was used the DNA barcoding gene cytochrome oxidase subunit I (COI) and conducting their phylogenetic trees. The effect of some biological factors on the chitin yield of crustaceans such as sex, size, and maturity stages of females’ ovaries was studied. Chitosan from E. massavensis and C. natator were produced, confirmed and characterized. Molecular identification of E. massavensis and C. natator were confirmed and agreed with the morphological description. The phylogenetic analysis revealed that E. massavensis had more affinity with E. woodmasoni than the Japanese mantis shrimp Oratosquilla oratoria. The phylogenetic analysis of genus charybdis revealed that C. variegata (KJ168053 and KX018513) should be redefined as C. natator. The chitin yield was significantly higher in E. massavensis than C. natator. The yield in E. massavensis males was significantly higher than females. The chitin yield of E. massavensis was the maximum from the individuals falling in the size range 90–130 mm body length. The yield was at its lowest in the immature stage of C. natator females’ ovaries. The crystalline structure of chitin polymer was ß-chitin in C. natator and α-chitin in E. massavensis. The use of microwaves in the deacetylation process produced chitosan with a high grade of purity and low molecular weight. These characterizations are ideal for medical applications.