. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 20 30 Time (ms). 50 100 150 Time (ms) 200 Figure 2. Force record of a fast swim response of a Pleiiminnniiiui xiphias adult female to a suprathreshold hydrodynamic stimulus. (A) Expanded temporal scale showing the first four kicks of the response. (B) Record showing the complete response to the stimulus. Stimulus: 700 H/,, cycles, maximum water velocity of 8400 /mi s~' at the rostrum. Piezoelectric transducer: PZL-060; vertical movement of sphere: 40 ;um; sphere diameter: mm; distance from center of ball to rostrum:
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 20 30 Time (ms). 50 100 150 Time (ms) 200 Figure 2. Force record of a fast swim response of a Pleiiminnniiiui xiphias adult female to a suprathreshold hydrodynamic stimulus. (A) Expanded temporal scale showing the first four kicks of the response. (B) Record showing the complete response to the stimulus. Stimulus: 700 H/,, cycles, maximum water velocity of 8400 /mi s~' at the rostrum. Piezoelectric transducer: PZL-060; vertical movement of sphere: 40 ;um; sphere diameter: mm; distance from center of ball to rostrum: mm (, second trace). similar in most respects to those of U. vnlgaris (Lenz and Hartline, 1999). They were characterized by short latencies, measured from the onset of the stimulus to the onset of the forward propulsion, typically around 10 ms (minimum: 6 ms). A weak brief backward propulsion, or "preparatory ; was observed in some animals immediately preceding the forward propulsion ( Fig. 3A, "Pr"). Following the peak of forward propulsion, there was often an irregular pattern of peaks and valleys for the remainder of the short stroke duration (mean: ms. Table I). As in U. vulgaris (Lenz and Hartline, 1999) and Calanux helgo- landicus (Svetlichnyy, 1987), the major peaks can be as- signed to the individual strokes of pereiopod pairs. Minor peaks caused by resonance in the underdamped force-trans- ducer system were also often apparent (Fig. 2A "res"). The distinct reverse propulsion following the termination of the forward phase was a feature found consistently in P. xiphius but not in previous studies on U. vulgaris. A pattern of multiple kicks in quick succession characterized a strong response to a stimulus. This is illustrated in Figure 2B, which shows the same response as Figure 2A on a com- pressed time scale. In P. xiphius, a train of kicks was typical, producing a cohesive propulsive response we term a &quo
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
