. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figures 9, 10, and 11. In each figure, the upper trace is a record of electrical activity from a comb plate while the lower is a laser beam record of the ciliary beating at the same spot. Figure 9 is a control (no stimulus). Figure 10 shows the response to a shock delivered orally of the recording electrode. Small upward events on the laser record corre- spond to reverse ciliary beats. Figure 11 shows the response to shock delivered aborally. Small downward events on the laser record correspond to fast forward beats. Spots m
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figures 9, 10, and 11. In each figure, the upper trace is a record of electrical activity from a comb plate while the lower is a laser beam record of the ciliary beating at the same spot. Figure 9 is a control (no stimulus). Figure 10 shows the response to a shock delivered orally of the recording electrode. Small upward events on the laser record corre- spond to reverse ciliary beats. Figure 11 shows the response to shock delivered aborally. Small downward events on the laser record correspond to fast forward beats. Spots mark shock artifacts. Scale bars: 100 ms, 500 nV (upper trace) (9); SO ms, 500 ^V (10); 50 ms, 200 ^V (11). with position along the comb row. In both cases, however, the response latency can clearly be less than 150 ms. The cilia generally appear to switch directly from one mode of beating to another without a break, but in some cases a short period of inactivity was observed before the new pattern emerged. During these periods, the cilia ap- peared to be in the "laydown" position described for Pleurobrachia (Moss and Tamm, 1986), but this needs to be verified. Comparison with other species We know of no previous reports of giant axons in the comb rows of ctenophores. We have looked at living spec- imens of Pleurobrachia bachei and Beroe sp. using the optical arrangement that enabled us to see the giant axons in Euplokamis (Fig. 2) and could see no comparable structures. We have cut some sections of Pleurobrachia and examined them under the EM with the same result, confirming Hernandez-Nicaise (1973a, 1974), who found only small-diameter neurites. Electrophysiological re- cordings from Beroe, made in the same way and at the same temperature (12°C) as Euplokamis. show the com- plex responses associated with excitation of the polster cells but no preceding neural event. Presumably the nerves conducting the excitation are too small and scattered to give a clear extracell
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
