Fluid Mechanics of Suction and Ram Feeding in Elasmobranchs.

吸力和喂羊的流体力学罗德岛大学谢丽尔·A·D·威尔加这项研究的总体目标是量化吸力和喂羊的鲨鱼和溜冰鞋嘴周围和进入嘴里的水的模式，并描述它的产生机制。鲨鱼嘴里的吸流是由嘴巴和颧腔的迅速扩张产生的，这会将猎物拉进嘴里。相比之下，公羊喂食者只需张大嘴巴，相对较小的扩张就能吞噬猎物。根据所展示的摄食形态和机制，本研究将研究三种鱼：竹鲨，专用于吸食；小溜鱼，斑嘴鲨，也专用于吸食；膨胀鲨，大头鲨，专用于公羊进食。这项研究的具体目的是：量化公羊和吸食鲨鱼和吸食溜冰鞋的肌肉和骨骼元素的解剖特征；建立涉及公羊和吸食鱼类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；使用声学显微测量来量化摄食过程中的头骨和鳃的运动；使用肌电和视频来量化被认为参与吸食产生的颅肌的活动模式；并使用数字粒子图像测速仪(DPIV)可视化和量化吸力和公羊喂入产生的水流模式。将这些技术结合在一起的综合方法将使我们能够更全面地了解解剖学、摄食机制、肌肉力量、吸力产生和水流之间的关系。这些目标包括两项尚未应用于鲨鱼摄食研究的技术：声学显微测量和DPIV。与视频相比，使用声学显微测量来量化运动的一个主要优点是，即使结构可能在外部不可见或已移出相机视野，也可以连续地记录移动结构的量化。这项相对较新的DPIV技术将提供直接的可视化和量化的发展，在整个摄食事件周围和进入喂食鲨鱼和溜冰鞋头部的水流。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，但由于缺乏准确的可量化的摄食器移动的液体图像，现在可以通过DPIV获得。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。这项研究将证明DPIV和声学显微测量在其他水生摄食脊椎动物研究中的有效性。此外，这项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，特别是脊椎动物的摄食机制的了解。最后，建议的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本的脊椎动物关键肌肉骨骼系统的进化提供基础：大多数人都同意溜冰鞋是从鲨鱼进化而来的。该研究将为进一步研究硬骨鱼、火蜥蜴等衍生脊椎动物的水生摄食流动机制奠定基础。

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.