Lawrence K A, Watson W H
Zoology Department & Center for Marine Biology, University of New Hampshire, Durham, New Hampshire 03824, USA.
Biol Bull. 2002 Oct;203(2):144-51. doi: 10.2307/1543383.
Swimming in the nudibranch Melibe leonina consists of five types of movements that occur in the following sequence: (1) withdrawal, (2) lateral flattening, (3) a series of lateral flexions, (4) unrolling and swinging, and (5) termination. Melibe swims spontaneously, as well as in response to different types of aversive stimuli. In this study, swimming was elicited by contact with the tube feet of the predatory sea star Pycnopodia helianthoides, pinching with forceps, or application of a 1 M KCl solution. During an episode of swimming, the duration of swim cycles (2.7 +/- 0.2 s [mean +/- SEM], n = 29) and the amplitude of lateral flexions remained relatively constant. However, the latency between the application of a stimulus and initiation of swimming was more variable, as was the duration of an episode of swimming. For example, when touched with a single tube foot from a sea star (n = 32), the latency to swim was 7.0 +/- 2.4 s, and swimming continued for 53.7 +/- 9.4 s, whereas application of KCl resulted in a longer latency to swim (22.3 +/- 4.5 s) and more prolonged swimming episodes (174.9 +/- 32.1 s). Swimming individuals tended to move in a direction perpendicular to the long axis of the foot, which propelled them laterally when they were oriented with the oral hood toward the surface of the water. The results of this study indicate that swimming in Melibe, like that in several other molluscs, is a stereotyped fixed action pattern that can be reliably elicited in the laboratory. These characteristics, along with the large identifiable neurons typical of many molluscs, make swimming in this nudibranch amenable to neuroethological analyses.
海蛞蝓Melibe leonina的游泳动作由以下五种类型的运动组成，按以下顺序发生：(1) 退缩，(2) 侧向扁平，(3) 一系列侧向弯曲，(4) 展开和摆动，以及(5) 终止。Melibe会自发游泳，也会对不同类型的厌恶刺激做出反应。在本研究中，通过与掠食性海星Pycnopodia helianthoides的管足接触、用镊子夹捏或施加1 M KCl溶液来引发游泳。在一次游泳过程中，游泳周期的持续时间（2.7±0.2秒[平均值±标准误]，n = 29）和侧向弯曲的幅度保持相对恒定。然而，刺激施加与游泳开始之间的潜伏期变化更大，游泳过程的持续时间也是如此。例如，当用海星的单个管足触碰时（n = 32），游泳潜伏期为7.0±2.4秒，游泳持续53.7±9.4秒，而施加KCl导致游泳潜伏期更长（22.3±4.5秒）且游泳过程持续时间更长（174.9±32.1秒）。游泳的个体倾向于朝着与足部的长轴垂直的方向移动，当它们的口盖朝向水面时，会横向推动它们。本研究结果表明，Melibe的游泳，与其他几种软体动物一样，是一种刻板的固定动作模式，在实验室中可以可靠地引发。这些特征，连同许多软体动物典型的可识别的大神经元，使得这种海蛞蝓的游泳适合进行神经行为学分析。
