Townsend Colin R, McCarthy T Kieran
Department of Zoology, Animal Ecology Research Group, South Parks Road, OX1 3PS, Oxford, UK.
Oecologia. 1980 Jul;46(1):75-79. doi: 10.1007/BF00346969.
Physa fontinalis (L.) gives a characteristic, chemically mediated escape response when stimulated by the majority of British leeches and flatworms. The snail responds rapidly and consistently to contact with all the molluskivorous leeches but also to three species which may be considered harmless. However, no response was given to Erpobdella octoculata, the most abundant and widespread of the harmless leeches. The flatworms generally evoked less strong reactions. The adaptive significance of the pattern of responsiveness is discussed. A weaker shell-shaking response is elicited in conspecifics and it is shown that this 'antisocial' behaviour leads to a relatively spaced-out dispersion pattern. A possible adaptive advantage is the reduction of risk of detection by shell-crushing fish predators, to which the snails are otherwise extremely vulnerable.
静水椎实螺（Physa fontinalis (L.)）在受到大多数英国水蛭和扁虫刺激时会产生一种由化学物质介导的特征性逃避反应。这种蜗牛对与所有食软体动物的水蛭接触都会迅速且一致地做出反应，对三种可能被认为无害的物种也会做出反应。然而，对于八眼蛭（Erpobdella octoculata），即最常见且分布最广的无害水蛭，它却没有反应。扁虫通常引发的反应较弱。文中讨论了这种反应模式的适应性意义。在同种个体中会引发较弱的壳振动反应，并且表明这种“反社会”行为会导致相对分散的分布模式。一个可能的适应性优势是降低被压碎贝壳的鱼类捕食者发现的风险，否则蜗牛极易受到这类捕食者的攻击。
