Chemoreception in the pigfish, Orthopristis chrysopterus: The contribution of amino acids and betaine to stimulation of feeding behavior by various extracts

1. 1. In extracts of crab, oyster, sea urchin and mullet, the major stimulants of feeding behavior in the pigfish, Orthopristis chrysopterus, were substances of less than ca. 1000 mol. wt. 2. 2. Quantitative analyses of betaine and the amino acids were conducted to permit the formulation of synthetic mixtures based on the composition of the four extracts. 3. 3. Synthetic mixtures of betaine and the amino acids could account for most of the stimulatory capacity of extracts of crab, oyster and mullet, but for only a small portion of that of sea urchin extract. 4. 4. Comparative tests of solutions containing betaine and/or the amino acids indicated that response elicitation by a particular extract could be due to one of four types of collaborative effects involving these (or other) substances.