• Shark Tracks
• Sharks and Tuna: High Speed Performers

 cont'd

To help Shadwick and Donley probe deeper into lamnid shark muscle dynamics, they employed an array of equipment and instrumentation—from tiny devices that precisely record muscle movement to video analysis of the animals in an ingenious swim tunnel that functions like a treadmill for fish. The research has shed new light on lamnid sharks' thrust-producing swimming that provides necessary bursts of speed for targeting prey.

The success of the lamnid shark research set the groundwork for the new study in Alaska where the scientists hoped to unravel the mystery of shark swimming even further. Lamnid sharks living in southern California waters can keep their temperatures elevated, but what about similar sharks living in much colder conditions, closer to freezing? Indeed, salmon sharks, which typically weigh several hundred pounds, live in an environment in which their internal temperatures differ from the outside water temperature by as much as 20° Celsius (35° Fahrenheit).

A group that includes Shadwick, Donley, Scripps alumnus Diego Bernal, who is now on the faculty at Weber State University in Utah, and Doug Syme of the University of Calgary studied these fish in unprecedented detail while in Alaska and are now analyzing the data they collected.

"This research is risky in that it's really hard to get access to the salmon sharks, and at the end of the day we might go home empty handed," Shadwick said. "But hopefully we will contribute to the knowledge of how muscles function by studying something that's an extreme-a fish that seems to have fish muscle in most of its body and warm, mammalian-like muscle stuck in there right in the middle to enhance its swimming performance. We shall see."

SCRIPPS INSTITUTION OF OCEANOGRAPHY