Vorticella convallaria are microscopic sessile suspension feeders that live attached to substrates in aquatic environments. They feed using a self‐generated current and help maintain the health of aquatic ecosystems and wastewater treatment facilities by consuming bacteria and detritus. Their environmental impact is mediated by their feeding rate. In ambient flow, feeding rates are highly dependent on an individual's orientation relative to the substrate and the flow. Here, we investigate how this orientation is impacted by flow speed. Furthermore, we examined whether individuals actively avoid orientations unfavorable for feeding. We exposed individuals to unidirectional laminar flow at shear rates of 0, 0.5, 1.0, and 1.5 s−1, and recorded their 3D orientation using a custom biplanar microscope. We determined that V. convallaria orientation became progressively tilted downstream as the shear rate increased, but individuals were still able to actively reorient. Additionally, at higher shear rates, individuals spent a larger fraction of their time in orientations with reduced feeding rates. Our shear rates correspond to freestream flows on the scale of mm s−1 to cm s−1 in natural environments.

中文翻译：

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外部流动对微观无柄悬浮饲养器 Vorticella convalaria 3D 方向的影响


铃藻是一种微小的固着悬浮饲养者，附着在水生环境中的基质上。它们利用自生电流进食，并通过消耗细菌和碎屑来帮助维持水生生态系统和废水处理设施的健康。它们对环境的影响是由它们的摄食率决定的。在环境流动中，进料速率高度依赖于个体相对于基质和流动的方向。在这里，我们研究了流速如何影响该方向。此外，我们还研究了个体是否主动避免不利于进食的方向。我们将个体暴露于剪切速率为 0、0.5、1.0 和 1.5 s−1 的单向层流中，并使用定制的双平面显微镜记录其 3D 方向。我们确定，随着剪切速率的增加，铃兰的方向逐渐向下游倾斜，但个体仍然能够主动重新定向。此外，在较高的剪切速率下，个体将大部分时间花在喂食速率较低的方向上。我们的剪切率对应于自然环境中 mm s−1 到 cm s−1 范围内的自由流。