Christina Gorlinsky (graduate student) attempting to induce a frog to perform a high dive to analyzed how cleanly it enters the water depending on jump height. Christina has been examining the swimming kinematics of the South American giant river otter (Pteronura brasiliensis) at the Philadelphia Zoo.

Graduate student Tricia Kojeszewski (foreground) recording frog diving with Christina Gorlinsky (background). Tricia finished her Master's thesis on the kinematics of swimming by the Florida manatee (Trichechus manatus latirostris). Her work showed that the manatee swam by undulation of the body and tail in a subcarangiform mode. The vertical movement of the tail tip was 22% of the body length with other points along the body moving vertically with smaller amplitudes over the propulsive cycle (below). Despite the structure of the tail and normally slow swimming speed, the manatee has a maximum propulsive efficiency of 0.82.

Kojeszewski, T. and Fish, F. E. 2007. Swimming kinematics of the Florida manatee (Trichechus manatus latirostris): Hydrodynamic analysis of an undulatory mammalian swimmer. Journal of Experimental Biology 210: 2411-2418. pdf

Lori Shannahan performed her research at the New Jersey State Aquarium, examining the mechanism by which sharks maintain trim. Lori found that the pectoral fins were canted at a positive angle of attack to ambient water flow. This alignment of the fins provided a positive torque to balance the upward torque developed by the caudal fin as the shark swam.

Fish, F. E. and Shannahan, L. D. 2000. The role of the pectoral fins in the body trim of sharks. Journal of Fish Biology 56: 1062-1073. pdf

Christopher Cuppels examined the planforms of the flippers, flukes, and dorsal fins different species of odontocete cetaceans as an independent study project. The plansforms shown are for Globicephala melaena (Gm), Tursiops truncatus (Tt), Stenella coeruleoalba (Sc), Grampus griseus (Gg), and Phocoena phocoena (Pp). Christopher also had an internship at the Philadelphia Zoo.

Rhyan Grech feeding a Golden Lion Tamarin in the tropical rainforest exhibit as part of her internship at the National Aquarium in Baltimore, Maryland.

Terrye Aigeldinger performed experiments on hydroplaning in mallard ducklings. Rapid escape behavior by mallard ducklings (Anas platyrhynchos) is restricted to burst swimming at the water surface. Maximum speed may be limited due to the pattern of waves created as the duckling's body moves through the water (hull speed). Terrye was able to show that ducklings were able to perform a maximum burst speed of 1.73 m/s, which was four times greater than the hull speed.  At burst velocities, stroke frequency was 1.9 times higher than the stroke frequency measured during steady low speed paddling. Transition to burst speeds from steady paddling occurred near hull speed. The paddling motions of the webbed feet were used to generate both thrust and lift as seen by the vortex pattern of the duckling shown above. By using lift to raise the body above the water surface, the influence of waves in restricting maximum swimming speed is negated. The duckling's body becomes a planing type of hull and skims on the water surface.

Aigeldinger, T. L., and Fish, F. E. 1995. Hydroplaning by ducklings: Overcoming limitations to swimming at the water surface. Journal of Experimental Biology, 198: 1567-1574. pdf

Jan Battle studied the hydrodynamic morphology of the flipper of the humpback whale (Megaptera novaeangliae). The flippers had cross-sectional geometries similar to engineered symmetrical foils (below). The flippers had leading edge tubercles that can modify the flow over the flipper's surface and delay stall. The delayed stall allows the flippers to be used to make tighter turns when foraging.

Fish, F. E. and Battle, J. M. 1995. Hydrodynamic design of the humpback whale flipper. Journal of Morphology, 225: 51-60. pdf

Jennifer Smelstoys studied the buoyancy of fur associated with semi-aquatic mammals. The pelts of sea otters, beaver, muskrat, Australian water rat, platypus, and mink were compared to the white rat and opossum. Jennifer found that the density of hair was correlated with the buoyancy, which was attributed to the volume of air entrapped in the fur. The highest buoyancy was found for the sea otter, which had the greatest number of hairs for a given area.

Fish, F. E., Smelstoys, J., Baudinette, R. V. and Reynolds, P. S. 2002. Fur doesn’t fly, it floats: buoyancy of hair in semi-aquatic mammals. Aquatic Mammals 28.2: 103-112. pdf

Jennifer Maresh analyzed the turning maneuvers of bottlenose dolphins (Tursiops truncatus) foraging on fish in Sarasota Bay, Florida. The worked was performed in cooperation with Douglas Nowacek of Florida State University, and Stephanie Nowacek and Randall Wells of the Mote Marine Laboratory. The foraging movements of the dolphins were videotaped from overhead using a remotely-controlled camera suspended from a helium-filled aerostat, which was tethered to an observation vessel. Dolphins could capture fish by moving the rostrum through small radius turns (mean- 0.20 body lengths; maximum- 0.08 body lengths) at a mean rate of turn of 561.6 deg/sec (maximum- 1,372.0 deg/sec). During the maneuver, dolphins rolled 90 degrees onto their side and flexed the body ventrally.

Maresh, J. L., Fish, F. E., Nowacek, D. P. and Nowacek, S. M. 2004.  High performance turning capabilities during foraging by bottlenose dolphins. Marine Mammal Science 20(3): 498-509. pdf

John Peacock is currently serving as a doctor in the U.S. Navy. John studied the morphology of dolphins in relation to pitch control during active swimming. From video, points on dolphins were digitized (below) to detail the changes in amplitude along the body. Position of control surfaces (flippers, flukes) and phasing of the body regions during dorso-ventral body oscillations minimized pitching movements in the anterior region of the body.

Fish, F. E., Peacock, J. E., and Rohr, J. J. 2003. Stabilization mechanism in swimming odontocete cetaceans by phased movements. Marine Mammal Science 19(3): 515-528. pdf

Moira Nusbaum was involved with the examination of the three dimensional geometry of biological control surfaces (i.e., fins, flippers, flukes). She examined CT scans of cetacean flukes to determine the cross-sectional design and how it might related to lift and thrust production. From this work, a study of the cross-sectional geometry of cetaceans flukes while being bent was initiated. When flukes were bent at 45 and 90 degrees as in swimming dolphins, the normally symmetrical cross-section was changed into a cambered cross-section. To measure the amount of cambering and flexure of the flukes, a Camber Index was developed, which ws the ratio of the chord line to the camber line. Chordwise bending occurred close to the central axis of the tail (i.e., between the two lateral flukes) and decreased distally.

Fish, F. E., Nusbaum, M. K., Beneski, J. T., and Ketten, D. R. 2006. Passive cambering and flexible propulsors: cetacean flukes. Bioinspiration and Biomimetics 1: S42-S48. pdf

Sandy Bostic performed experiments to study the kinematics of the death roll of alligators. The death roll is used by crocodilians to subdue and dismember prey. Spinning is initiated after the fore- and hind limbs are appressed against the side of the body and the head and tail are canted at an angle to the longitudinal body axis.

Fish, F. E., Bostic, S. A., Nicastro, A. J. and Beneski, J. T. 2007. Death roll of the alligator: mechanics of twist feeding in water. Journal of Experimental Biology 210:2811-2818. pdf

Mariela Muniz was involved with analysis of the three-dimensional geometry of biological control surfaces (i.e., flippers, flukes, fins). The geometry of these structures was determined from CT scan images, which were collected at the Natural History Museum of the Smithsonian Institution and Woods Hole Oceanographic Institution.

Taylor Black examined the swimming of woodchucks. Although woodchucks are noted for travelling on land and burrowing, they are capable of swimming. These rodents use a modified quadrupedal, terrestrial gait when swimming. Taylor also did an internship at the Philadelphia Zoo.

Lori Timm (graduate student) is shown with a stranded minke whale. The necropsy of the whale was performed at the Pathology Laboratory at the University of Pennsylvania Veterinary School at the New Bolton Center.

For her graduate research, Lori has been examining the hydrodynamics of the flow through the shark nose. As the nasal apparatus is blind cavity, Lori wanted to find out how the nasal capsule was ventilated. Lori used a combination of techniques including morphometrics, gross dissection, dye injection in a flow tank and medical imaging with computer tomography (CT) scans. She was able to find that internal and external flaps direct the flow smoothly through the capsule from incurrent to excurrent nostrils. Her research has application in understanding the olfactory ecology of different shark species and in biomimetics for engineering of artificial noses.

Jana Parson is currently examining the maneuverability of stingrays from the National Aquarium in Baltimore, Maryland.

Brittany Fredericks examined the underwater locomotion of the hippopotamus (Hippopotamus amphibius)at the Adventure Aquarium in Camden, NJ. The hippo is negatively buoyant and uses a modified terrestrial gait as it moves along the bottom. Despite the hippo's immense size, it has no difficulty travelling on the bottom. The movements of the hippo allude to locomoting in a microgravity environment.

Beth Schuelkens is performing a comparative study of the three-dimensional geometry of flippers of marine mammals, including the Florida manatee, dolphins, sea lions, and seals. Using images from computer tomography (CT) scans, Beth is analyzing the geometry with respect to hydrodynamic performance.

Sara Farjo, holding a model of a minke whale flipper, has been working on the differences in the planar geometry of whale and dolphin flippers.

Carly Ginter is researching the morphology and function of micro-tubercles in marine mammals.