Collaborative Research: Hydrodynamic and Muscular Mechanical Investigation of Maneuverability in Cephalopods throughout Ontogeny

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Squids and cuttlefishes are impressive swimmers, having the ability to hover, change direction rapidly, and even swim forward and backward with ease. The key to their locomotive prowess is coordination among their pulsed jet, flapping fins, and flexible arms, but little is presently known about how these units work together throughout these animals' lives as they encounter different physical environments, change developmentally, and experience dissimilar ecosystems. This project focuses on understanding how the jet, fins, and arms operate in concert to produce the necessary forces for exceptional turning, both in terms of muscle capabilities and hydrodynamics, in squid and cuttlefish of different developmental stages (hatchlings to adults). This work will involve cutting edge 3D flow visualization approaches, high-speed video analysis, and advanced mathematical tools that highlight the essential components of high-performance turns. This project promises to (1) advance our understanding of how highly maneuverable marine animals navigate through their complex habitats and (2) reveal key performance characteristics, structures, and behaviors that can be integrated potentially into the design of mechanical bio-inspired systems, such as autonomous underwater vehicles, to improve their turning/docking capabilities. This project incorporates a number of outreach projects, including demonstrations in local schools, participation in robotics competitions, development of web-based tutorials and summer camps, and presentations at aquariums and museums. Maneuvering in the aquatic environment is a significant component of routine swimming, with proficient maneuvering being essential for predator avoidance, prey capture, and navigation. Despite its importance, understanding of the biomechanics of maneuvering behaviors is limited. An investigation of maneuvering performance in three morphologically distinct species of cephalopods is proposed here. The investigation explores three broad questions: (1) how are the fins, arms, and funnel-jet complex used in concert to maximize turning performance in adult cephalopods; (2) do the relative importance of turning rate and turning radius change over ontogeny and are fewer turning modes observed in young cephalopods; and (3) do fin, arm, and funnel musculoskeletal mechanics change over ontogeny and are such changes associated with differences in maneuvering? These questions will be addressed by collecting measurements of 3D high-speed kinematics and 2D/3D hydrodynamics of wake flows; performing mathematical analyses to quantitatively identify and categorize turning patterns; and measuring both the dynamic passive and active length-force relationship and maximum shortening velocity of muscle fibers that drive the movements used during turning and jet vectoring. The proposed work will: (1) provide data on how an ecologically important marine animal coordinates its novel dual-mode system (jet and fins) and arms to achieve high turning performance, (2) highlight the essential kinematic and hydrodynamic elements of turns, (3) offer insights into how maneuvering capabilities change over a broad ontogenetic range, and (4) provide novel data on the muscle properties of muscular hydrostatic organs and their role in turning.