Gilbert John J
Department of Biological Sciences, Dartmouth College, 03755, Hanover, NH, USA.
Oecologia. 1985 Jun;66(3):322-331. doi: 10.1007/BF00378293.
Cinefilms of unconstrained P. vulgaris at 17°C were taken at a low magnification (∼2x) and 120-200 fps to analyze body movements during swimming and escape responses mediated by movements of the 12 lateral, bladelike appendages or paddles. Cinefilms of partially constrained P. vulgaris and P. dolichoptera at 16°C were taken at a higher magnification (∼10x) and 300 fps, using interference contrast optics, to resolve paddle movements during escape responses. When swimming, P. vulgaris moved at a velocity of 0.348±0,025 (S.E.) mm·s (2.64 body lenghs·s), having a Reynolds number of 0.05. During escape responses, P. vulgaris traveled 1.947±0.124 (S.E.) mm (15 body lengths) during 0.0564±0.0038 (S.E.) s, continuously moving at a velocity of 35.7±1.2 (S.E.) mm·s (270 body lengths·s) and having a Reynolds number of 5. During these responses, P. vulgaris tumbled sinuously but mostly-88.9±2.3 (S.E.) %-in a constant direction; the angular change in direction from one frame to the next was 28±2 (S.E.) degrees, but the sign of the change in direction frequently alternated. Escape responses are caused by 1-3 cycles of paddle movements. In each cycle, the rigid paddles move up asynchronously until they are all directly overhead, and then they move downwards to their original resting positions, again asynchronously. Polyarthra's body moves along the flight path during all phases of this cycle. A single cycle may take as little as 26 ms, 13 ms for the paddles to elevate and 13 ms for them to descend. The asynchronous upward and downward movements of each of the 12 paddles explain why Polyarthra's body tumbles continuously through its low Reynolds number, viscous environment. Escape responses generally were initiated by contact with another rotifer. In one P. dolichoptera response, the time lag between such contact and the initiation of paddle elevation was about 7 ms. The very short lag time, great velocity, considerable displacement, and unpredictable directionality of Polyarthra's escape response make it a very effective defense against capture by some invertebrate predators.
在17°C下对自由状态的普通多肢轮虫拍摄电影，拍摄时放大倍数较低（约2倍），帧率为120 - 200帧/秒，以分析其游泳时的身体运动以及由12个侧向叶片状附属物或桨的运动介导的逃避反应。在16°C下对部分受限的普通多肢轮虫和长多肢轮虫拍摄电影，拍摄时放大倍数较高（约10倍），帧率为300帧/秒，使用干涉对比光学系统，以解析逃避反应过程中的桨的运动。普通多肢轮虫游泳时的速度为0.348±0.025（标准误）毫米·秒（2.64体长·秒），雷诺数为0.05。在逃避反应中，普通多肢轮虫在0.0564±0.0038（标准误）秒内移动了1.947±0.124（标准误）毫米（15个体长），持续移动速度为35.7±1.2（标准误）毫米·秒（270体长·秒），雷诺数为5。在这些反应中，普通多肢轮虫蜿蜒翻滚，但大部分时间——88.9±2.3（标准误）%——朝一个恒定方向；从一帧到下一帧方向的角度变化为28±2（标准误）度，但方向变化的符号经常交替。逃避反应由1 - 3个桨运动周期引起。在每个周期中，刚性桨异步向上移动，直到它们都直接位于头顶上方，然后再异步向下移动到其原始静止位置。多肢轮虫的身体在这个周期的所有阶段都沿着飞行路径移动。一个周期可能短至26毫秒，桨上升需要13毫秒，下降也需要13毫秒。12个桨各自的异步向上和向下运动解释了为什么多肢轮虫的身体在其低雷诺数的粘性环境中持续翻滚。逃避反应通常由与另一只轮虫接触引发。在一次长多肢轮虫的反应中，这种接触与桨开始上升之间的时间间隔约为7毫秒。多肢轮虫逃避反应的极短延迟时间、高速度、相当大的位移和不可预测的方向性使其成为抵御一些无脊椎动物捕食者捕获的非常有效的防御手段。
