Collaborative Research. Ontogenetic Changes in Swimming Squid: An Integrative Examination of Jet Structure and Muscular Mechanics

项目摘要：合作研究。游泳鱿鱼的个体发育变化：喷射结构和肌肉力学的综合研究老道明大学的Ian K.Bartol，圣约瑟夫大学的Joseph T.Thompson和南方卫理公会大学的Paul S.Krueger是多才多艺的游泳运动员，能够在一个地点徘徊，明显轻松地快速改变方向或方向，几乎垂直上升/下降。尽管鱿鱼的鳍和臂在不同程度上用于推进、稳定性和机动性，但脉冲喷气是机车系统的基础。鱿鱼体内的脉冲射流不同于鱼类、水生爬行动物和水生哺乳动物更常见的波动运动，它是通过交替向内部地幔空腔装满水，并通过可操纵的漏斗通过强大的地幔收缩将水喷出而产生的。脉冲喷射被不同大小的鱿鱼使用，从只有几毫米长的小乌贼到成年乌贼可以长到18米。在这个宽广的大小范围内，流体物理在各种喷射特征(例如，被称为涡环的特征涡旋)的演变中发挥着重要作用，这些特征是推进游泳性能的核心。这个合作项目调查流体机械约束如何影响不同生活史阶段的鱿鱼的游泳策略和肌肉力学，最终目标是评估推进效率如何随着大小的变化而变化。为了实现这一点，我们将研究两种鱿鱼的喷射流、身体运动和肌肉特性，这两种鱿鱼分别是短吻乌贼和椭圆形乌贼。这些鱿鱼的总长度从幼体的1厘米到成年的15厘米不等，它们将被训练在装有播撒有光反射颗粒的水的流动水池(即水上“跑步机”)中游泳。当富含颗粒的水从漏斗中排出时，将用激光照射并拍摄下来，这样就可以使用一种名为数字粒子图像测速仪(DPIV)的技术来确定射流速度。这些DPIV数据将提供喷气特性和推进效率的直接测量。安装在电动轨道系统上的多个摄像机将被用来收集鱿鱼游泳时外套膜和漏斗的高分辨率图像，为游泳行为提供有价值的数据。由于地幔的收缩特性随着尺寸的变化而变化，并对喷流有直接影响，因此也将使用标准的肌肉机械技术对孤立的地幔肌束进行详细测量。DPIV、游泳片段和肌肉力学数据的整合有望扩大我们对喷气推进生物体推进效率的理解，特别是在对喷气机制知之甚少的低尺寸范围内，并提供对肌肉骨骼支持系统个体发育变化的洞察。这些数据不仅与生物研究人员有关，也与合成喷气和脉冲喷气微型飞行器等新兴技术的工程师和设计师有关。这个项目将吸引本科生和研究生参与跨学科研究。它还将通过直接参与实验或通过在当地公立学校和水族馆发展教育来促进少数族裔学生的参与。

PROJECT ABSTRACTCollaborative Research. Ontogenetic Changes in Swimming Squid: An Integrative Examination of Jet Structure and Muscular MechanicsIan K. Bartol (Old Dominion University), Joseph T. Thompson (Saint Joseph's University), and Paul S. Krueger (Southern Methodist University)Squids are versatile swimmers, having the ability to hover in one spot, change direction or orientation rapidly with apparent ease, and ascend/descend almost vertically. Although squids have fins and arms that are used to varying degrees for propulsion, stability, and maneuverability, it is the pulsed jet that is the foundation of the locomotive system. Pulsed jets in squids, which differ from the more familiar undulatory locomotion of fishes, aquatic reptiles, and aquatic mammals, are generated by alternately filling an internal mantle cavity with water and ejecting that water by powerful mantle contractions through a maneuverable funnel. Pulsed jetting is used by squids of remarkably different sizes, from hatchlings that are only a few millimeters in length to adults that may grow as large as 18 m. Over this wide size range, the physics of fluids plays an important role in the evolution of various jet features (e.g., characteristic vortices known as vortex rings) that are central to propulsive swimming performance. This collaborative project investigates how fluid mechanical constraints shape swimming strategies and muscular mechanics in squid of different life history stages, with the ultimate goal of assessing how propulsive efficiency changes with size. To accomplish this, jet flows, body movements, and muscle properties will be examined in two species of squids, the brief squid Lolliguncula brevis and the oval squid Sepioteuthis lessoniana. These squids, which vary in total length from 1 cm as hatchlings to 15 cm as adults, will be trained to swim in a flow tank (i.e., an aquatic "treadmill") containing water seeded with light-reflective particles. As particle-laden water is expelled from the funnel, it will be illuminated with lasers and videotaped so that the jet velocity can be determined using a technique known as digital particle image velocimetry (DPIV). These DPIV data will provide direct measurements of jet features and propulsive efficiency. Multiple video cameras positioned on a motorized rail system will be used to collect high-resolution images of the mantle and funnel as the squids swim, providing valuable data on swimming behavior. Because the contractile properties of the mantle change with size and have direct effects on jet flows, detailed measurements of isolated bundles of mantle muscle also will be made using standard muscle mechanical techniques. The integration of DPIV, swimming footage, and muscle mechanical data promises to broaden our understanding of propulsive efficiency in jet-propelled organisms, especially at low size ranges where little is known about the jet mechanism, and provide insight into the evolution of ontogenetic changes in musculoskeletal support systems. These data are relevant not only for biological investigators but also for engineers and designers of emerging technologies, such as synthetic jets and pulsed-jet micro-vehicles. This project will engage undergraduate and graduate students in interdisciplinary research. It will also facilitate minority student involvement, either through direct participation in experiments or through educational development in local public schools and aquariums.