Computational Fluid Dynamics Analysis of the Fossil Crinoid Encrinus liliiformis (Echinodermata: Crinoidea).
Computational Fluid Dynamics Analysis of the Fossil Crinoid Encrinus liliiformis (Echinodermata: Crinoidea).
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DOI：
10.1371/journal.pone.0156408
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Roth-Nebelsick A
中科院分区：
文献类型：
--
作者：
Dynowski JF;Nebelsick JH;Klein A;Roth-Nebelsick A
海百合是棘皮动物门的成员，是被动悬浮摄食者，捕捉浮游生物而不产生主动摄食流。如今，只有在深水栖息地才知道这种有柄的形式，那里的水流条件相当恒定，进食速度也相对较低。为了进食，它们形成一个典型的抛物线过滤扇，其手臂向后弯曲进入水流。相比之下，化石记录提供了大量生活在浅水环境中的有柄海百合，与现存海百合的深海栖息地相比，其流速和方向变化更快。此外，一些化石代表可能不像今天的海百合那么灵活，对于这些形式，假设有不同的进食位置。其中一种海百合化石是 Encrinus liliiformis，生活在中欧三叠纪中期的 Muschelkalk 时期。所提出的项目使用计算流体动力学研究不同的进食姿势，以分析百合百合冠周围形成的流动模式，包括通过粒子图像测速进行的实验验证。该研究包括对不同流向、速度以及冠方向的分析。结果表明，来自侧面和口腔的流入导致浮游生物颗粒直接输送到牙冠和口腔表面。当电流来自海百合的“后”（口部）侧时，冠部的圆锥形开口在其尾流中产生向后流动，将颗粒输送到冠部。结果表明，与抛物线过滤风扇相比，锥形进料位置可能较少依赖于稳定的流动条件。因此，假设百合艾美鱼的圆锥形摄食姿势适合在动态变化的水流条件下摄食，该条件是上Muschelkalk浅海环境的典型特征。
Crinoids, members of the phylum Echinodermata, are passive suspension feeders and catch plankton without producing an active feeding current. Today, the stalked forms are known only from deep water habitats, where flow conditions are rather constant and feeding velocities relatively low. For feeding, they form a characteristic parabolic filtration fan with their arms recurved backwards into the current. The fossil record, in contrast, provides a large number of stalked crinoids that lived in shallow water settings, with more rapidly changing flow velocities and directions compared to the deep sea habitat of extant crinoids. In addition, some of the fossil representatives were possibly not as flexible as today’s crinoids and for those forms alternative feeding positions were assumed. One of these fossil crinoids is Encrinus liliiformis, which lived during the middle Triassic Muschelkalk in Central Europe. The presented project investigates different feeding postures using Computational Fluid Dynamics to analyze flow patterns forming around the crown of E. liliiformis, including experimental validation by Particle Image Velocimetry. The study comprises the analysis of different flow directions, velocities, as well as crown orientations. Results show that inflow from lateral and oral leads to direct transport of plankton particles into the crown and onto the oral surface. With current coming from the “rear” (aboral) side of the crinoid, the conical opening of the crown produces a backward oriented flow in its wake that transports particles into the crown. The results suggest that a conical feeding position may have been less dependent on stable flow conditions compared to the parabolic filtration fan. It is thus assumed that the conical feeding posture of E. liliiformis was suitable for feeding under dynamically changing flow conditions typical for the shallow marine setting of the Upper Muschelkalk.