. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 100 10 100 Duration (sec) 1000 FIGURE 11. Effects of reduction in intensity of upward (A and B) and downward (C) directed light beams of 3000 lux. The reduced levels: 0 lux for curves a and a', 3 lux for curves b and b', 30 lux for curves c and 300 lux for curves d. Ordinates: Cumulative percentages of worms (n = 30) that responded with critical periods shorter than those shown on abscissae. A and C show the percentages of worms that moved upward. B shows percentages of downward moving worms, plotted in such a way that downw
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 100 10 100 Duration (sec) 1000 FIGURE 11. Effects of reduction in intensity of upward (A and B) and downward (C) directed light beams of 3000 lux. The reduced levels: 0 lux for curves a and a', 3 lux for curves b and b', 30 lux for curves c and 300 lux for curves d. Ordinates: Cumulative percentages of worms (n = 30) that responded with critical periods shorter than those shown on abscissae. A and C show the percentages of worms that moved upward. B shows percentages of downward moving worms, plotted in such a way that downward directed lines indicate higher percentages of downward movements. rakami, 1959; Pearre, 1973; Nagasawa and Marumo, 1975; Kotori, 1976; Hirota, 1979; Goto, 1980). Light has been considered a major factor controlling these movements. However, most work has been done in the field and little attention has been paid to behavior or physiology of individual worms in relation to environmental conditions. In addition to confirming the findings of Esterly (1919) and Pearre (1973) that worms are basically negatively geotactic, coming to the water surface when placed in darkness (Fig. 4), and that a horizontal light beam of moderate intensities makes worms gather on an illuminated side (Fig. 1), we have presented several new facts regarding light-oriented movements of arrow worms, Sagitta crassa (summary diagram in Fig. 12). arrowworm (geonegative) change in orientation — negative kinetic effect photopositive •change in sign of geotaxis arousal increase releaser• hv reduction \ mechanical shocks I etc. I /discrete light\ I source j sight target and steer for it rapid swimming (darkness. FIGURE 12. Summary diagram of the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woo
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
