Swimming and Sinking Behavior of Warm Water Pelagic Snails
Swimming and Sinking Behavior of Warm Water Pelagic Snails
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DOI：
10.3389/fmars.2020.556239
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发表时间：
2020-09
期刊：
影响因子：
2.4
通讯作者：
Ferhat Karakas;Jordan Wingate;L. Blanco-Bercial;Amy E. Maas;D. Murphy
中科院分区：
文献类型：
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作者：
Ferhat Karakas;Jordan Wingate;L. Blanco-Bercial;Amy E. Maas;D. Murphy
中上层蜗牛的游动和下沉行为的研究很少，但在它们的生态学、捕食者-猎物相互作用和垂直分布方面是重要的。利用低倍、高速立体摄影测量系统，研究了9种温水中上层钉螺(7种)的游动和下沉运动学。由于不同的肿瘤性翼足类物种可能具有卷曲、细长或球状的壳形态，从流体力学的角度出发，我们重点研究了壳的形状、身体几何形状和身体大小如何影响它们的游泳行为。此外，对垂直分层的MOCNESS样本进行了ZooScan图像分析和元编码，以将游泳行为与夜间和白天的垂直分布联系起来。虽然观察到了不同的大尺度游动模式，但所有物种都表现出因附肢相互拍打而产生的小尺度锯齿状游动轨迹。壳体的游动和下沉行为与壳的形态和大小有很强的对应关系，其中微小的盘状壳翼足类游动和下沉最慢，大型球壳翼足类游动和下沉最快，中等大小的细长壳翼足类游动和下沉速度中等。然而，盘壳翼足类的归一化游泳和下沉速度最高，最高可达45个体长的S-1。盘状和拉长壳翼足类的下沉轨迹几乎是垂直的，但球形壳翼足类使用其水翼状的壳在垂直方向约20°处向下滑行，从而减缓了它们的下沉速度。游动雷诺数(Re)从盘状壳体[Re∼O(10)]增加到细长壳体[Re∼O(100)]，再到球形壳体[Re∼O(10)]，这表明较新的谱系在尺寸上增加并改变了壳体形态，以获得在较高Re时可获得的更大升阻比。游泳速度与垂直迁徙的程度无关，强调了其他因素，可能包括光、温度以及捕食者和猎物的领域，影响了这一重要的生态特征。大小确实在垂直栖息地的结构中发挥了作用，较大的个体往往生活在水柱更深的地方，而在一个物种内，较大的个体有更深的迁徙。
Swimming and sinking behavior by pelagic snails is poorly studied but is important in their ecology, predator-prey interactions, and vertical distributions. We used a low magnification, high speed stereophotogrammetry system to study the swimming and sinking kinematics of nine warm water pelagic snail species (seven thecosomes, one gymnosome, and one heteropod). As different thecosomatous pteropod species may have coiled, elongated, or globular shell morphologies, we focused on how the shell shape, body geometry, and body size affect their swimming behavior from a fluid mechanics perspective. In addition, ZooScan image analysis and metabarcoding of archived vertically stratified MOCNESS samples were used to relate swimming behaviors to night time and daytime vertical distributions. While different large scale swimming patterns were observed, all species exhibited small scale sawtooth swimming trajectories caused by reciprocal appendage flapping. Thecosome swimming and sinking behavior corresponded strongly with shell morphology and size, with the tiny coiled shell pteropods swimming and sinking the slowest, the large globular shelled pteropods swimming and sinking the fastest, and the medium-sized elongated shell pteropods swimming and sinking at intermediate speeds. However, the coiled shell species had the highest normalized swimming and sinking speeds, reaching swimming speeds of up to 45 body lengths s–1. The sinking trajectories of the coiled and elongated shell pteropods were nearly vertical, but globular shell pteropods use their hydrofoil-like shell to glide downwards at approximately 20° from the vertical, thus retarding their sinking rate. The swimming Reynolds number (Re) increased from the coiled shell species [Re ∼ O(10)] to the elongated shell species [Re ∼ O(100)] and again for the globular shell species [Re ∼ O(1000)], suggesting that more recent lineages increased in size and altered shell morphology to access greater lift-to-drag ratios available at higher Re. Swimming speed does not correlate with the vertical extent of migration, emphasizing that other factors, likely including light, temperature, and predator and prey fields, influence this ecologically important trait. Size does play a role in structuring the vertical habitat, with larger individuals tending to live deeper in the water column, while within a species, larger individuals have deeper migrations.