Abstract:
Two series of experiments were performed on the oriented locomotor responses of 27 specimens of the blind cave fish Phreatichthys andruzzii from Somalia using a three-compartment choice apparatus. The oriented responses were observed individually from the central compartment towards either of the extreme ones. In one of them, 500 ml water were introduced from either the tank in which the test fish had previously resided with conspecifics (lst series, 46 experiments) or from another tank occupied by unknown conspecifics, the other compartment receiving an equivalent of pure water. The two series were performed in random blocks of 6 experiments, the momentary position of the test fish being noted every 30 seconds after an adaptation period of at least 4 hours. Results, analyzed in 9 blocks of 5 minutes show a definite preferential orientation of the fishes for the compartment containing chemical information from both known or unknown conspecifics. This effect is discussed in relation to the ecological conditions in which the species under study lives.