Das Geruchsorgan des TiefseefischesAphanopus carbo (Percomorphi,Trichiuridae)

The paper deals with the structure of the olfactory organ, its accessory parts and the forebrain in the deep-sea fishAphanopus carbo. On each side of the head only one opening leads to the olfactory chamber. The olfactory folds are arranged in a rosette-like pattern, resembling the 360°-type. Secondary folds on the main folds may serve as an enlargement of the surface of the olfactory epithelium. Most of the surface area of the olfactory folds is covered by the olfactory epithelium, indicating that the receptive area is of optimal extension. The histological structure of the olfactory epithelium is similar to that in other teleost species. The number of olfactory receptors amounts to about 5×10⁶ to 10⁷ for the single organ. Numerous secretory cells of unknown function are located within the olfactory epithelium. The olfactory chamber is enlarged by three accessory sacs: Two ethmoidal sacs and one lacrymal sac (consisting of two parts). These sacs serve as ventilation aparatus which causes a permanent water current within the olfactory chamber and between the olfactory folds. The action of the accessory sacs is induced by the splanchnokinetic. The forebrain ofAphanopus carbo is well developed; its size ranges between that of forebrains in microsmatic and macrosmatic teleost species. A detailed investigation of the forebrain is in preparation. The diagnosis of the different parts of the olfactory apparatus ofAphanopus carbo demonstrates clearly that — in addition to the eye — this sense organ is well developed (relative to that in other teleosts). This fact suggests thatAphanopus carbo is related to a group of teleost species characterized by optical and olfactory orientation mechanisms of high performance.