. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 313 225. 135 180 180 Figure 4. Initial directional choices for sea stars during different odor stimulations for mussel sources. Solid dots represent heading angle in relation to odor source for the first movement of the animal. There were no significant mean angles in any of the groups, indicating that the initial headings were uniformly distributed around the circle; n = 14 for all groups. We found changes in the orientation paths to be a function of distance from the odor source. For all of our stimulus conditions except o
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 313 225. 135 180 180 Figure 4. Initial directional choices for sea stars during different odor stimulations for mussel sources. Solid dots represent heading angle in relation to odor source for the first movement of the animal. There were no significant mean angles in any of the groups, indicating that the initial headings were uniformly distributed around the circle; n = 14 for all groups. We found changes in the orientation paths to be a function of distance from the odor source. For all of our stimulus conditions except one, we found that the head- ing angle relative to the odor source decreased as an ani- mal approached the odor source. In other words, as it approached the odor source, the animal began to walk in a straighter line towards the source. Since we did not find similar results with the control or shell studies, we con- clude that the locomotory output of the animal is influ- enced by the chemical stimulus whether it is perceived spatially or temporally. In addition, walking speed and turning angles did not change as a function of distance. Although these results are consistent with either orienta- tion mechanism, we feel that the behavioral patterns of our animals in the absence of macroscale flow are more compatible with a taxis-based orientation strategy then with a kinesis strategy (as denned by Dusenbery, 1992). This finding is similar to that of Rochette el al. (1994), who convincingly demonstrated that other species of sea stars were capable of showing directed responses, but that these directional choices were dependent upon their physiological state (starved vs. fed) and the ambient cur- rent flow. Their finding may be due to decisions based on dual sensory information (that is, from both the odor signal and ambient coalitions of macroscale flow), whereas we provided main, -hemosensory cues. Third, A. forbesi respond^ ;fferently to the various stimulus sources by having dis
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