Fluid Mechanics of Suction and Ram Feeding in Elasmobranchs.

在ELASMOBRANCHSCheryl ad . Wilga，罗德岛大学这项研究的总体目标是量化水在吸力和RAM喂养鲨鱼和溜冰鱼的嘴周围和流入的模式，并描述其产生的机制。鲨鱼嘴部的吸力流是由嘴部和鳃腔的快速扩张产生的，它把猎物拉进嘴里。相比之下，公羊捕食者只是张大嘴巴，用相对较小的扩张来吞噬猎物。本研究将根据竹鲨的摄食形态和摄食机制对三种竹鲨进行研究：竹鲨，Chiloscyllium plagiosum，专为吸力摄食；小冰鞋（Raja erinacea）也专门用于吸吮喂养；而大头鲨（cephalaloscyllium ventriosum）是专门以公羊为食的动物。利用这些物种，将对以往关于公羊和吸力摄食鱼类的解剖和吸力产生机制的假设进行检验。本研究的具体目的是：量化公羊、吸食性鲨鱼和吸食性鳐的肌肉和骨骼成分的解剖特征；构建包括冲击力和吸力喂养的力和速度，以及各种肌肉和骨骼元素输出的生物力学模型；用声速测量法量化进食过程中颅骨和鳃的运动；使用肌电图和视频，量化被认为参与产生吸力的颅肌的活动模式；并使用数字粒子图像测速（DPIV）可视化和量化由吸入和冲压进料产生的水流模式。结合这些技术的综合方法将使我们更全面地了解解剖学、喂养机制、肌肉力量、吸力产生和水流之间的关系。这些目标包括两种尚未应用于鲨鱼摄食研究的技术：声速测量法和DPIV。与视频相比，使用声测法量化运动的一个主要优点是，即使结构在外部可能不可见或已经移出摄像机视野，也可以记录运动结构的连续量化。相对较新的DPIV技术将提供直接的可视化和量化水流的发展周围和进入喂食鲨鱼和鳐鱼的头部在整个喂食事件。这一直是许多对水生脊椎动物摄食机制感兴趣的研究人员的目标，但由于缺乏喂食器移动的液体的精确量化图像而受到阻碍，现在可以使用DPIV。这个项目意义重大，因为它将提高我们对产生吸力的内部肌肉和运动学事件及其与流体流动的关系的理解。本研究将证明DPIV和声速测量法在其他水生摄食脊椎动物研究中的有效性。此外，拟议的研究将通过评估解剖学在功能中的作用，增加我们对脊椎动物，特别是弹性分支动物摄食机制的认识。最后，本研究将有助于我们理解摄食行为和脊椎动物肌肉骨骼机制的进化。这项研究将为解释最基础的颌口动物的关键肌肉骨骼系统的进化提供基础：大多数人同意滑冰动物是从鲨鱼进化而来的。对现存最古老的有颌脊椎动物的研究将为进一步研究更多衍生脊椎动物（如硬骨鱼和蝾螈）的水生摄食流动机制提供基础。

FLUID MECHANICS OF SUCTION AND RAM FEEDING IN ELASMOBRANCHSCheryl A.D. Wilga, University of Rhode IslandThe overall goal of this research is to quantify the pattern of water flow around and into the mouths of suction and ram feeding sharks and skates, and to describe the mechanism by which it was generated. Suction flow into the mouth of a shark is generated by rapid expansion of the mouth and gill cavities, which pulls the prey into the mouth. In contrast, ram feeders simply open their mouths wide and engulf their prey with relatively little expansion. Three species based on the type of feeding morphology and mechanism exhibited will be investigated in this study: bamboo sharks, Chiloscyllium plagiosum, are specialized for suction feeding; little skates, Raja erinacea, are also specialized for suction feeding; and swellsharks, Cephaloscyllium ventriosum, are specialized ram feeders. Using these species, previous hypotheses about the anatomy of ram and suction feeding fishes and the mechanism of suction generation will be tested.The specific aims of this research are to: quantify the anatomical characteristics of the muscular and skeletal elements of the ram and suction feeding sharks and a suction feeding skate; construct biomechanical models that involve the force and speed of ram and suction feeding, and output of various muscular and skeletal elements; quantify cranial and gill movements during feeding using sonomicrometry; quantify activity patterns of cranial muscles thought to be involved in the generation of suction using electromyography and video; and visualize and quantify the patterns of water flow generated by suction and ram feeding using digital particle image velocimetry (DPIV). The integrative approach in combining these techniques will allow a fuller understanding of the relationship between anatomy, feeding mechanism, muscular effort, suction generation, and water flow.These objectives include two techniques that have yet to be applied to studies of shark feeding: sonomicrometry and DPIV. A major advantage of quantifying movements using sonomicrometry over video is that continuous quantification of moving structures are recorded even though structures may not be visible externally or have moved out of camera view. The relatively new technique of DPIV will provide direct visualization and quantification of the development of water flow around and into the head of feeding sharks and skates throughout the feeding event. This has been the goal of many researchers interested in the feeding mechanism of aquatic vertebrates, but has been hampered by the lack of accurate quantifiable images of the fluid moved by the feeder, now available with DPIV. This project is significant in that it will improve our understanding of the internal muscular and kinematic events that generate suction and their relationship to fluid flow. This study will demonstrate the usefulness of DPIV and sonomicrometry for studies of other aquatic feeding vertebrates. In addition, the proposed research will increase our knowledge of feeding mechanisms in vertebrates, and elasmobranchs in particular, by evaluating the role of anatomy in function. Finally, the proposed research will contribute to our understanding of feeding behavior and the evolution of vertebrate musculoskeletal mechanisms. This research will provide a basis for interpreting the evolution of key musculoskeletal systems in the most basal of gnathostomes: most agree that skates have evolved from sharks. This study on the most ancestral of all living jawed vertebrates will provide the basis for further studies on the flow mechanics of aquatic feeding in more derived vertebrates, such as bony fishes and salamanders.