Technical University of Denmark, Department of Physics and Centre for Ocean Life, DK-2800 Kgs. Lyngby, Denmark.
Technical University of Denmark, National Institute of Aquatic Resources and Centre for Ocean Life, DK-2920 Charlottenlund, Denmark.
Sci Rep. 2017 Jan 5;7:39892. doi: 10.1038/srep39892.
Many unicellular flagellates are mixotrophic and access resources through both photosynthesis and prey capture. Their fitness depends on those processes as well as on swimming and predator avoidance. How does the flagellar arrangement and beat pattern of the flagellate affect swimming speed, predation risk due to flow-sensing predators, and prey capture? Here, we describe measured flows around two species of mixotrophic, biflagellated haptophytes with qualitatively different flagellar arrangements and beat patterns. We model the near cell flows using two symmetrically arranged point forces with variable position next to a no-slip sphere. Utilizing the observations and the model we find that puller force arrangements favour feeding, whereas equatorial force arrangements favour fast and quiet swimming. We determine the capture rates of both passive and motile prey, and we show that the flow facilitates transport of captured prey along the haptonema structure. We argue that prey capture alone cannot fulfil the energy needs of the observed species, and that the mixotrophic life strategy is essential for survival.
许多单细胞鞭毛虫是混合营养的，它们通过光合作用和捕食来获取资源。它们的适应性取决于这些过程，以及游泳和逃避捕食者的能力。鞭毛虫的排列和鞭毛的拍打模式如何影响游泳速度、由于流动感应捕食者而导致的捕食风险，以及猎物的捕获？在这里，我们描述了两种具有不同鞭毛排列和拍打模式的混合营养双鞭毛甲藻的测量周围流。我们使用两个对称排列的点力来模拟近细胞流，这些点力的位置可以在无滑移球体旁边变化。利用观察结果和模型，我们发现拉力器的排列有利于摄食，而赤道力的排列有利于快速和安静的游泳。我们确定了被动和运动猎物的捕获率，并表明流动有助于将捕获的猎物沿着触毛结构运输。我们认为，仅仅是猎物的捕获并不能满足所观察到的物种的能量需求，因此混合营养的生活策略对于生存是必不可少的。
