1. To deal with predation threats, many prey organisms have evolved anti‐predator defences in both morphology and behaviour. Aquatic rotifers were among the first model organisms for studying inducible defences and studies mainly focused on predator‐induced morphological defences. Despite this, we still lack a good understanding of predator‐induced behavioural defences in rotifers.
2. In this study, we conducted three laboratory induction experiments to investigate floating behavioural responses of the prey rotifer Brachionus calyciflorus to the presence of the predator Asplanchna sieboldii and its chemical cues. Two experiments used live A. sieboldii and one used A. sieboldii‐conditioned medium. Subsequently, we examined the protective effects of floating behaviour against predation by Asplanchna by performing predation experiment.
3. We show that B. calyciflorus has a pronounced behavioural response to A. sieboldii and that this response can be induced by both exposure to live A. sieboldii and to Asplanchna‐conditioned medium. We also found that. B. calyciflorus can respond with floating behaviour immediately within 10 min when exposed to Asplanchna‐conditioned medium.
4. We also provide the first experimental evidence that the floating behaviour of B. calyciflorus reduces the predation rate from A. sieboldii by about 50%, and effectively protects them from consumption by this predator. Thus, we concluded that B. calyciflorus can sense chemical cues released during predation by A. sieboldii and use behaviour as a defence, escaping to the water surface as a refuge, thereby reducing predation risk.
5. Our results represent a novel addition to our fundamental knowledge on how prey may not be passive victims, but rather actively use inducible behavioural defences to counteract their vulnerability to predators.

中文翻译：

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花椰菜对捕食天蛾Asebechna sieboldii的行为反应

1. 为了应对捕食威胁，许多猎物有机体在形态和行为方面都发展了反捕食者防御。水生轮虫是最早研究诱导型防御的典型生物之一，而研究主要集中于捕食者诱导的形态防御。尽管如此，我们对轮虫中捕食者诱导的行为防御仍然缺乏很好的了解。
2. 在这项研究中，我们进行了三次实验诱导实验，调查浮猎物轮虫的行为反应萼花臂尾到捕食者的存在晶囊女花和它的化学线索。两个实验中使用活一个。 天女和一个用过的甲。 sieboldii条件培养基。随后，我们通过进行捕食实验，研究了浮游行为对Asplanchna捕食的保护作用。
3. 我们表明，乙。 花萼对A有明显的行为反应。 sieboldii认为可以通过接触活的A来诱导这种反应。 sieboldii和Asplanchna条件培养基。我们也发现了这一点。乙。 轮虫可以与在暴露于10分钟内立即漂浮行为响应Asplanchna-条件培养基。
4. 我们还提供了第一个实验证明B的浮动行为。 Calyciflorus降低了A的捕食率。 sieboldii约减少了50％，并有效地保护了它们免受捕食者的消费。因此，我们得出的结论是乙。 Calyciflorus可以感知A捕食期间释放的化学线索。 天女和使用行为辩护，泄漏到水面作为避难所，从而减少捕食风险。
5. 我们的研究结果为我们的基础知识提供了一种新颖的补充，即关于捕食者可能不是被动的受害者，而是积极地使用可诱导的行为防御来抵消其对掠食者的脆弱性。