Many animals interact with the air-water interface during locomotion. Such location either involves moving through the water's surface or moving atop the water surface. This dissertation aims to investigate both of these forms of locomotion in frogs. First we quantified the kinematics of skittering, jumping on top the water's surface without sinking, in two species of frog, Acris crepitans and Euphlyctis cyanophlyctis. We found that what was described as "skittering" locomotion in Acris crepitans is actually more akin to porpoising. A. crepitans begins and ends each jump during their interfacial behavior under the water surface. These frogs may be unable to perform true skittering locomotion due to not being able to retract their hindlimbs fast enough. E. cyanophlyctis, however, does stay above the water surface during this mode of locomotion. We found that Euphlyctis is highly maneuverable during skittering locomotion compared to other inertial based water-surface traversing animals. Not only can they turn up to 80° between subsequent jumps, they also perform this behavior in close proximity to each other without collision. Next, we investigated control mechanisms used by frogs when jumping from water. Prior research has identified frogs of the genus Euphlyctis as high jumpers. But previous studies only considered their maximal performance. Here, we investigated how these frogs modulate propulsive force in order to control their jump height. We linked the frog limb kinematics to the jump force by modeling the added mass produced by the foot's motion. / Doctor of Philosophy / There are many animals that move across or through the water's surface. Most of them are very small and light and can thus be supported by surface tension. Larger animals instead must produce the force needed to stay afloat by moving quickly. Previous research has looked at the physics involved in running on the water surface in basilisk lizards and grebes. However, the ability of frogs to jump on the water surface (a behavior known as "skittering") has never been studied. In this dissertation, we examine the water-surface traversal of two frog species, Acris crepitans and Euphlyctis spp., using high-speed videography. Unlike previous human observations in the literature, we found that Acris does not stay atop the water's surface during its jumping behavior and instead begins and ends each jump under the water. This is similar to porpoising in animals like dolphins. Euphlyctis, however, does stay above the water during this jumping behavior. We found that these frogs can turn sharply between jumps which has not been observed in any other large water-runners. Additionally, we studied the ability of Euphlyctis to jump high in the air starting from floating on the water surface. These frogs are interesting to study because they can jump unusually high compared to other species of similar size and shape. We found that when shown insects at different heights, these frogs can control their jump height and only jump as high as necessary. By tracking the frogs' limbs during jumping we investigated several possible ways these frogs controlled their jump height.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/113621 |
| Date | 01 February 2023 |
| Creators | Weiss, Talia M. |
| Contributors | Engineering Science and Mechanics, Socha, John J., Ross, Shane D., Jung, Sunghwan, Boreyko, Jonathan B., Gillis, Gary |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International, http://creativecommons.org/licenses/by-nc-sa/4.0/ |
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