Chemoreception in the Mud Snail, Nassarius Obsoletus. I. Properties of Stimulatory Substances Extracted From Shrimp

The mud snail, Nassarius obsoletus, was shown to be an excellent test animal for studies of chemoreception. This snail responds to substances diffusing from dead animals by giving a series of extensions of the proboscis. With this response as the criterion, a bioassay procedure was developed for studying the properties of substances which contribute to the response-inducing capacities of shrimp extracts. N. obsoletus can be used in studies in which it is desirable to compare in a quantitative manner the response-inducing capacities of closely related solutions. 2. The principal response-inducing compounds in shrimp extracts were heat stable, more soluble in polar than in non-polar solvents, non-volatile, of low molecular weight, alkali-stable, partially acid-labile, and resistant to oxidation. 3. Separations of shrimp extracts on ion exchange columns revealed that the principal response-inducers were amphoteric and/or weakly basic compounds which were augmented by some acidic and/or neutral compound (s). 4. Changes in pH within the range 5.8-8.0 had no detectable effect upon the responsiveness of N. obsoletus to a shrimp extract.