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Ian Bartol







1) Quantification of Propulsor Coordination in Squids
For this project, my collaborators and I are examing how multiple propulsors (fins and jet) in squid are used in coordination for efficient swimming. We are using a quantitative metrics approach, with volumetric particle image velocimetry being central to our data collection efforts. This project promises to provide unprecedented 3-dimensional data on complex flows commonly observed in biological systems, expanding our knowledge of vortex-based force production and coordination.

FUNDING: This research is supported by the National Science Foundation.

2) Ontogenetic Changes in Swimming Squid: An Integrative Examination of Jet Structure and Muscle Mechanics.
Collaborators: Dr. Joseph Thompson and Dr. Paul Krueger
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 investigated 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 jet efficiency changes with size. My component of the project was to investigate swimming mechanics of squids throughout ontogeny.  This was accomplished by studying squid swimming in water seeded with light-reflective particles in custom-built chambers or water tunnels. As particle-laden water was expelled from the funnel, it was illuminated with lasers and videotaped so that the jet velocity could be determined using a technique known as digital particle image velocimetry (DPIV).  These DPIV data provided direct measurements of jet features and propulsive efficiency.  Multiple video cameras positioned on a motorized rail system were used to collect high-resolution images of the mantle and funnel as the squids swam, providing valuable data on swimming behavior.  

Some of the key findings of this work related to my component of the project are described in the following papers:


Bartol, I. K., Krueger, P. S., Stewart, W. J. and Thompson, J. T. (2009). Hydrodynamics of pulsed jetting in juvenile and adult brief squid Lolliguncula brevis: evidence of multiple jet 'modes' and their implications for propulsive efficiency. J. Exp. Biol. 212, 1889-1903 [pdf].


Bartol, I. K., Krueger, P. S., Stewart, W. J. and Thompson, J. T. (2009). Pulsed jet dynamics of squid hatchlings at intermediate Reynolds numbers. J. Exp. Biol. 212,1506-1518 [pdf].


Krueger, P.S., A.A. Moslemi, J.T. Tyler, I.K. Bartol, and W.J. Stewart.  (2008).  Vortex rings in bio-inspired and biological jet propulsion.  Adv. Sci. Tech. 58: 237-246. <pdf>


Bartol, I.K., P.S. Krueger, J.T. Thompson, and W.J. Stewart.  (2008).  Swimming dynamics and propulsive efficiency of squids throughout ontogeny.  Int. Comp. Biol. 48, 720-733.  <pdf>


FUNDING:  This research was supported by the National Science Foundation and the Jeffress Memorial Trust.


3) Role of Fins in Propulsion of the Brief Squid Lolliguncula brevis
Collaborators: William J. Stewart, Paul S. Krueger, and Dr. Joseph Thompson 

Although there is considerable diversity in fin form and function in squids, the locomotive role of the fins is not well understood.  While the jet is the foundation of the locomotive system for most squids, the fins also play important roles in swimming, providing thrust, lift, and dynamic stability.  In this project, several high-speed video cameras were used to record the kinematics of fin motion in the brief squid Lolliguncula brevis, and DPIV was used to study flows around the fins as they undulate/oscillate over a range of swimming speeds. 


Some of the key findings of this work are included in the following papers:


Bartol, I.K., P.S. Krueger, J.T. Thompson, and W.J. Stewart.  (2008).  Swimming dynamics and propulsive efficiency of squids throughout ontogeny.   Int. Comp. Biol. 48, 720-733.  <pdf>


Stewart, W. J., Bartol, I. K., and Krueger, P. S. (2009). Hydrodynamic fin function of brief squid Lolliguncula brevis. J. Exp. Biol. 213, 2009-2024. <pdf>


FUNDING:  This research was supported by the National Science Foundation and the Jeffress Memorial Trust.




1) Hearing Capabilities of Loggerhead Sea Turtles (Caretta caretta) throughout Ontogeny: An Integrative Approach involving Behavioral and Electrophysiological Techniques

Collaborators: Dr. Soraya Moein Bartol


Little is currently known about sea turtle auditory systems.  For this study, we are using electrophysiological and behavioral techniques to study hearing capabilities of sea turtles throughout ontogeny.  All experiments are being conducted at the National Oceanic and Atmospheric Administration (NOAA) Fisheries Galveston Laboratory, TX.  The data collected for this project will serve as an integral component of future assessment plans that address potential impacts of sound on sea turtles. 


FUNDING: This project is funded by the Joint Industry Program of the International Association of Oil and Gas Producers.

2) Swimming Mechanics of Sea Turtles
Collaborators: Dr. Soraya Moein Bartol and Mark Swingle (Virginia Aquarium and Marine Science Center)
Little is known about swimming mechanics and hydrodynamics of sea turtles, especially during migratory behavior.  In this study, the kinematics and dynamics of swimming are being studied in sea turtles as they locomote against steady currents in a water tunnel (i.e., an aquatic treadmill). 
1) Role of the Carapace and Fins of Boxfishes in Stability and Maneuverability

Collaborators: Dr. Malcolm Gordon, Dr. Mory Gharib, Dr. Paul Webb, Dr. Daniel Weihs

Boxfishes are marine fishes having rigid carapaces that vary significantly among taxa in their shapes and structural ornamentation.   Using three separate but interrelated approaches (DPIV, pressure distribution measurements, and force balance measurements),  we determined that four species of boxfishes produce vortices around their keels that lead to self-correcting trimming forces during swimming.  For example, when a boxfish pitches upward in a turbulent environment, spiral flows develop above the keels and are strongest at the posterior edge of the carapace.  The low pressures that result from the vortices pull the back-end of the fish upwards, returning it to a level trajectory.  This sophisticated self-correcting systems acts quickly and automatically without neural processing and reduces the complexity of boxfish swimming movements, which saves energy and enhances sensory acuity.  Interestingly, systems that are stable are generally not very maneuverable because every change in course is counteracted by the stabilizing mechanism.  However, boxfishes are unique because they are both stable and maneuverable!  Current work on boxfishes focuses on how fins interact with body-induced flows to enhance maneuverabilty.
Results from our work were recently appiled to the development of Mercedes-Benz's bionic car. and are being used by Navy to make more efficient underwater robots.

The key findings of this work are described in the following papers:


Bartol, I.K., M.S. Gordon, P.W. Webb, D. Weihs, M. Gharib. (2008). Evidence of self-correcting spiral flows in swimming boxfishes. Bioinsp. Biomim. 3:1-7. <pdf>

Bartol, I.K., M. Gharib, P.W. Webb, D. Weihs, and M.S. Gordon. (2005). Body-induced vortical flows: a common mechanism for self-corrective trimming control in boxfishes J. Exp. Biol. 208: 327-344. <pdf>

Bartol, I.K., M. Gharib, D. Weihs, P.W. Webb, J.R. Hove, and M. S. Gordon. (2003). Hydrodynamic stability of swimming in ostraciid fishes: role of the carapace in the smooth trunkfish Lactophrys triqueter (Teleostei: Ostraciidae). J. Exp. Biol. 206: 725-744. <pdf>

Bartol, I.K., M.S. Gordon, M. Gharib, J. Hove, P.W. Webb, and D. Weihs. (2002). Flow patternsaround the carapaces of rigid-bodied, multi-propulsor boxfishes (Teleostei: Ostraciidae). Int. Comp. Biol. 42: 971-980.

FUNDING: This work was funded by the Office of Naval Research. 


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