Ontogeny of respiration and feeding structures of skull in Persian sturgeon, Acipenser persicus (Bordin, 1897)

In the present study, the process of the skull development and calcification in Persian sturgeon (Acipenser persicus) was studied. Development of cartilage started after hatching around the head and notochord (10.6 mm, total length, TL) and the first calcification process occurred in dermopalatine and dentary bone jaw coincident with mixing feeding. The appearance of dermal skeletal on the body divided into three stages: (a) the yolk-sac (comprised of hatching to the late larval stage (12 DPH, 16 mm TL) in which no calcified structures became visible and the cartilaginous elements of skull with feeding and breathing roles have appeared. (b) the larval stage (between 16 and 20.25 mm, 23 DPH) in which, the first calcification process related to feeding and breathing occurred and weak mineralized dermal bones such as subopercle and supracleithrum developed; and (c) the metamorphosis stage between 27.25 and 83.3 mm TL) during which the formation of mineralized dermal bones occurred between 32 and 50 days post-hatching, and teeth were disappeared on dentary and dermopalatine bones. The results of this study could be useful for decreasing the larval mortality and improving the stock conservation programme of Persian sturgeon.