Even subtle changes in environmental factors can exert behavioral effects on creatures, which may alter interspecific interactions and eventually affect the ecosystem. However, how changes in environmental factors impact complex behaviors regulated by neural processes is largely unknown. The freshwater planarian Dugesia japonica, a free-living flatworm, displays distinct behavioral traits mediated by sensitive perception of environmental cues. Planarians are thus useful organisms for examining interactions between environmental changes and specific behaviors of animals. Here we found that feeding behavior was suppressed when the concentration of ions in the breeding water was low, while other behaviors were unaffected, resulting in differences in population size. Notably, the decline in feeding behavior was reversed in an ion-concentration-dependent manner soon after the planarians were moved to ion-containing water, which suggests that ions in environmental water rapidly promote feeding behavior in planarians. Moreover, the concentration of ions in the environmental water affected the feeding behavior by modulating the sensitivity of the response to foods. Finally, we found that calcium ions in the aquatic environment were required for the feeding behavior, and exposure to higher levels of calcium ions enhanced the feeding behavior, showing that there was a good correlation between the concentration of calcium ions and the responsiveness of planarians to foods. Environmental calcium ions are indispensable for and potentiate the activity level of the feeding behavior of planarians. Our findings suggest that the ions in the aquatic environment profoundly impact the growth and survival of aquatic animals via modulating their neural activities and behaviors.

中文翻译：

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水生环境中的钙离子驱使涡虫进食

即使环境因素的细微变化也会对生物产生行为影响，这可能会改变种间的相互作用并最终影响生态系统。然而，环境因素的变化如何影响由神经过程调节的复杂行为在很大程度上是未知的。淡水涡虫 Dugesia japonica 是一种自由生活的扁虫，表现出由对环境线索的敏感感知介导的独特行为特征。因此，涡虫是检查环境变化与动物特定行为之间相互作用的有用生物。在这里，我们发现当养殖水中的离子浓度较低时，摄食行为受到抑制，而其他行为不受影响，从而导致种群大小的差异。尤其，在涡虫被转移到含有离子的水中后不久，摄食行为的下降以依赖于离子浓度的方式逆转，这表明环境水中的离子迅速促进了涡虫的摄食行为。此外，环境水中的离子浓度通过调节对食物反应的敏感性来影响摄食行为。最后，我们发现水生环境中的钙离子是摄食行为所必需的，并且暴露于较高水平的钙离子会增强摄食行为，表明钙离子浓度与涡虫对食物的反应性之间存在良好的相关性。食物。环境钙离子对于涡虫的摄食行为的活动水平是必不可少的，并且可以增强它们的活性水平。