Response of Asterias vulgaris to chemical stimuli

Groups of the sea star Asterias vulgaris approached a variety of chemical stimuli in a flow tank. Urea, lactic acid, succinic acid, and handsweat were attractive to some animals; some simple acids and amino-acid mixtures were weakly attractive; pH changes and sea-water salts were not attractive. Although the groups were similarly maintained and responded with high internal consistency, they differed in responsiveness to different substances. These variations are not easily accounted for as contamination or effects of prior animal experience. A. vulgaris detects many simple organic substances, but the behavioral response is not constant and species-wide; it depends on nonchemical factors. This sensory/behavioral mode presumably suits a nonspecialist predator, and may be widespread among similar asteroids. Individuals attracted to lactic acid could be induced to cling to and evert their stomachs over a sponge soaked in lactic-acid solutions. The chemicals found atrractive in this study do not account for most of the attractiveness of shellfish tissue extracts studied previously.Contribution No. 2854 of the Woods Hole Oceanographic Institution.