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

项目摘要合作研究。游泳乌贼的个体发生变化：射流结构和肌肉力学的综合检查sian K. Bartol （Old Dominion大学），Joseph T. Thompson（圣约瑟夫大学）和Paul S. Krueger（南卫理公会大学）鱿鱼是全能的游泳者，有能力在一个地方盘旋，明显轻松地迅速改变方向或方向，几乎垂直上升/下降。尽管乌贼的鳍和臂在不同程度上用于推进、稳定性和机动性，但脉冲射流才是其动力系统的基础。乌贼的脉冲射流不同于我们更熟悉的鱼类、水生爬行动物和水生哺乳动物的波动运动，它是通过交替地将水填满内部地幔腔，并通过可操作的漏斗通过强大的地幔收缩将水喷射出来而产生的。使用脉冲喷射的鱿鱼大小差别很大，小到只有几毫米长，大到可以长到18米。在如此大的尺寸范围内，流体的物理特性在各种射流特征（例如，被称为涡环的特征涡）的演变中起着重要作用，这些特征对推进游泳性能至关重要。该合作项目研究流体力学约束如何影响鱿鱼不同生活史阶段的游泳策略和肌肉力学，最终目标是评估推进效率如何随尺寸变化。为了做到这一点，我们将研究两种鱿鱼的射流、身体运动和肌肉特性，这两种鱿鱼分别是短鱿鱼Lolliguncula brevis和椭圆形鱿鱼Sepioteuthis lessoniana。这些鱿鱼的总长度从刚孵化时的1厘米到成年时的15厘米不等，它们将被训练在一个流动池（即水生“跑步机”）中游泳，其中含有含有光反射颗粒的水。当充满颗粒的水从漏斗中喷出时，将用激光照射并录像，以便使用一种称为数字粒子图像测速（DPIV）的技术来确定喷射速度。这些DPIV数据将提供喷气特性和推进效率的直接测量。安装在机动轨道系统上的多个摄像机将用于收集乌贼游泳时地幔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大小而变化，并对射流有直接影响，因此也将使用标准肌肉机械技术对孤立的地幔肌肉束进行详细测量。DPIV、游泳镜头和肌肉力学数据的整合有望扩大我们对喷气推进生物推进效率的理解，特别是在对喷气机制知之甚少的小尺寸范围内，并为肌肉骨骼支持系统的个体发生变化的进化提供见解。这些数据不仅与生物研究人员有关，而且与新兴技术的工程师和设计师有关，例如合成射流和脉冲射流微型飞行器。该项目将吸引本科生和研究生进行跨学科研究。它还将促进少数民族学生的参与，通过直接参与实验或通过当地公立学校和水族馆的教育发展。

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.