Observations on the Postembryonic Development of the Olfactory Organs in Sarotherodon galilaeus Linnaeus (Teleostei, Cichlidae) PDF

Keywords

fish, olfactory organs, Egypt

Abstract

The postembryonic development of the olfactory organs was studied in five developmental stages of the Nile cichlid fish Sarotherodon galilaeus (= Tilapia galilaea) including two buccal stages (5 and 7 mm) and three bostbuccal ones (9, 12 and 58 mm total length). In the buccal stages, the olfactory organ on each side is simple and represented by the olfactory epithelium and a narrow olfactory chamber opening externally through a single aperture on the dorsolateral surface of the snout. As development proceeds in the postbuccal stages, however, two accessory nasal sacs are developed: a dorsomedial sac and a ventrolateral sac, both are connected with the main olfactory chamber. Based on the analysis position of the accessory nasal sacs, in relation to the surrounding skeletal parts of the head, the mechanism of water pumping may have been operated by the respiratory movements as well as movements of the jaws in opening and closing of the mouth.