Hydrodynamic performance of suction feeding is virtually unaffected by variation in the shape of the posterior region of the pharynx in fish

To capture prey by suction, fish generate a flow of water that enters the mouth, and exits at the back of the head. It was previously hypothesized prey-capture performance is improved by a streamlined shape of the posterior region of the pharynx, which enables an unobstructed outflow with minimal hydrodynamic resistance. However, this hypothesis remained untested for several decades. Using computational fluid dynamics simulations, we now managed to quantify the effects of different shapes of the posterior pharynx on the dynamics of suction feeding, based on a feeding act of a sunfish (Lepomis gibbosus). In contrast to what was hypothesized, the effects of the imposed variation in shape were negligible: flow velocity patterns remained essentially identical, and the effects on feeding dynamics were negligibly small. This remarkable hydrodynamic insensitivity implies that, in course of the evolution, the observed wedge-like protrusions of the pectoral surfaces of the pharynx probably resul...

为通过抽吸方式捕获猎物，鱼类会生成一股水流，该水流从口腔进入、从头部后方排出。此前有研究假说认为，咽部后端的流线型结构可提升猎物捕获性能，使水流能够以最小的水动力阻力实现无阻碍流出。然而，该假说数十年来始终未得到验证。本研究基于驼背太阳鱼（Lepomis gibbosus）的一次摄食行为，借助计算流体动力学（computational fluid dynamics）模拟，量化了咽部后端不同形状对抽吸摄食动力学的影响。与原假说相悖的是，形状变化带来的影响微乎其微：水流速度模式基本保持一致，对摄食动力学的影响也极小。这一显著的水动力不敏感性表明，在进化历程中，咽部胸侧表面观察到的楔形突起可能源于……