KINGSTON, R.I. -- May 24, 2001 -- If you were able to keep your eyes open during the feeding frenzy of Jaws, you have a visual introduction to the work of the University of Rhode Islands Cheryl Wilga, an assistant professor in the Biological Sciences Department. Wilga, a North Kingstown resident, studies how sharks use their upper jaw when feeding. "Its a mechanism that wasnt known when the movie was made," says the biologist who has always been fascinated by the way things work. In biology lingo, thats called functional morphology.
According to Wilga, a petite Alaskan Indian who came to URI last year following a National Science Foundation postdoctoral fellowship at Harvard University, the shark lifts its head, depresses its lower jaw, its upper jaw comes out, it bites, and then the upper jaw retracts under the head. Unlike humans, the sharks upper jaw isnt fused to its cranium.
To discover exactly how sharks eat, Wilga videotapes small spotted bamboo sharks while they munch on lunch in her lab. The high-speed film produces 500 images every second. Wilga then downloads the video into a computer and slows down the action to see exactly what the shark is doing and how it is doing it.
Wilga takes measurements of the angle of the sharks fins, how wide it opens its mouth, and how fast it captures its prey. She also monitors up to 12 muscles with electrodes as thin as a piece of hair to determine which muscles are used, a process called electromyography.
Wilga also researches how sharks swim. "The old theory was that sharks swim like airplanes fly," says the researcher, who notes that textbooks still state this. The old theory is that as wings of an airplane provide lift, the sharks pectoral fins also provide lift. Using fluid dynamics and lasers a technique called digital particle image velocimetry or DPIV, which measures the forces the fish places on the water, Wilga was able to see the water moving around the shark and to see that sharks swim at a
Contact: Jan Sawyer
University of Rhode Island