Olfactory responses from a marine elasmobranch, the atlantic stingray,Dasyatis sabina

Underwater electro‐olfactogram (EOG) responses were recorded from the olfactory organ of the Atlantic stingray, Dasyatis sabina. Amino acids were shown to be effective stimuli with thresholds determined to be between 10−6 and 10−8 M. The five most stimulatory compounds tested were l‐glutamic acid γ methylester, l‐ethionine, l‐serine, l‐glutamic acid, and l‐methionine. The D‐isomer of alanine was much less stimulatory than the l‐isomer. The EOG response magnitude increased exponentially with logarithmic increase (spanning 4–5 log units) of stimulus concentration. Due to shunting of signals by the highly conductive seawater, response magnitudes to 10−3 Ml‐alanine averaged only 0.2 mV, approximately 40 to 50 times less than the magnitude seen at the same concentration in a freshwater fish.