. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CHEMORECEPTION AND BEHAVIOR IN ASTEROIDS 413 ing a Neuman-Keuls analysis. A linear regression analy- sis was used to correlate changes in parameter values with distance from source. Distance from the source for regression analysis was the Euclidean distance between the source point (0, 0) and the animal's position within the tank (described above). NGR was calculated by di- viding the Euclidean distance from start to finish (net) by the total path length (gross). These values can range from 0 to 1, with 0 being a very circui
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CHEMORECEPTION AND BEHAVIOR IN ASTEROIDS 413 ing a Neuman-Keuls analysis. A linear regression analy- sis was used to correlate changes in parameter values with distance from source. Distance from the source for regression analysis was the Euclidean distance between the source point (0, 0) and the animal's position within the tank (described above). NGR was calculated by di- viding the Euclidean distance from start to finish (net) by the total path length (gross). These values can range from 0 to 1, with 0 being a very circuitous path, and 1 being a linear path. Turn angle was denned as the angle between the path connecting the previous (/ = -!) position to the present (/ = 0) position and the path connecting the pres- ent to the next (/ = +!) position (Moore el ai, 1991). A sea star's heading was defined as the angle between a straight line towards the source and the direction from the present position to the next position on the track, with an angle of zero pointing directly at the source (Moore el ai. 1991). All angles were calculated in a clockwise fashion. The initial directional choice for each sea star was re- corded as the heading angle for initial movement from the starting point. A modification of the Rayleigh's test (The I 'test) was used to determine whether the heading angles were uniformly distributed around the circle or if there was a significant directionality to the movement (Zar, 1984). For this test, we assumed a priori that an angle of zero degrees towards the odor source was ex- pected. Results General orientation results Our criteria for successful orientation resulted in rejec- tion of 52% of the total number of trials. Successful trials resulted in different paths that depended upon the odor source (Fig. 1). Most rejections were due to the animal's inability to locate the odor source; very few of the trials were rejected due to lack of movement by the animal. This high rate
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
