The cannibalistic snail <i>Agaronia propatula</i> (Caenogastropoda, Mollusca) is reluctant to feed on autotomized ‘tails’ of conspecifics

Autotomy and cannibalism increase the complexity of the life history, population structure, and population dynamics of a species. Species in which autotomy is triggered by cannibalism have rarely been studied. It has been hypothesized that in the intertidal gastropod <i>Agaronia propatula</i>, autotomized tissues are highly attractive to cannibals and so increase the victim’s chance to escape. We tested the hypothesis by presenting autotomized ‘tails’ to foraging animals. The attack rates on autotomized ‘tails’ were lower than those on artificial objects reported previously. Autonomously moving autotomized ‘tails’ were more frequently ignored than non-moving and artificially moved ‘tail’ pieces. Thus, autotomized tissue repelled rather than attracted potential cannibals. Autotomy in <i>A. propatula</i> does not help to defend against cannibalism by offering the cannibal an attractive food item for consumption. It seems possible, though, that autotomized conspecifics are less attractive to cannibals than intact ones due to a repelling action of autotomized tissues.自切（autotomy）与同类相食（cannibalism）会提升物种的生活史、种群结构与种群动态的复杂程度。目前鲜有针对由同类相食触发自切的物种开展的研究。已有假说提出，在潮间带腹足类<em>Agaronia propatula</em>中，自切脱落的组织对同类相食者具有极强吸引力，进而提升被捕食者的逃脱概率。我们通过向觅食个体呈现自切脱落的“尾部”样本，对该假说开展了验证。实验结果显示，自切脱落“尾部”的受攻击率低于此前文献报道的人工诱饵。自主移动的自切“尾部”相较于静止及人工移动的“尾部”片段，被忽略的频率更高。由此可见，自切脱落的组织对潜在同类相食者起到驱避作用，而非吸引作用。<em>A. propatula</em>的自切行为，无法通过向同类相食者提供诱人的可食用食物来实现防御目的。不过，鉴于自切脱落组织的驱避效应，自切后的同种个体相较于完整个体，对同类相食者的吸引力或更低，这一推测具备可能性。