Wednesday September 30, 2026
Cornell Chronicle—
When designing a large underwater robot that could swim silently to avoid startling sea creatures, roboticist Rob Shepherd considered the unusual swimming system of oarfish, the meters-long fish whose ribbon-like dorsal fin moves in waves to propel its body.
To learn more, he consulted his colleague Willy Bemis ’76, a retired Cornell ichthyologist.
“He called me and said, ‘I’m interested in oarfish,’ and I said, ‘me too,’” said Bemis, professor emeritus of ecology and evolutionary biology in the College of Agriculture and Life Sciences.
That was the start of a collaboration to study the oarfish’s unique dorsal fin rays. Oarfish, giant fish that are rarely spotted by humans, have hundreds of these bone-like skeletal structures, which extend from the back of the oarfish. The fin rays move in coordinated motion, creating waves along the membrane that connects the fin rays, which, in turn propels the fish.
A new study, published Sept. 30 in the journal Ichthyology and Herpetology, is the first to describe the anatomy and series of muscles that allow each of the oarfish’s fin rays to rotate independently in a full circle, like a joystick. Bemis is the paper’s senior author, while Shepherd, the John F. Carr Professor of Mechanical Engineering in the Cornell Duffield College of Engineering, is a co-author. Gabriel Afonso, a former visiting researcher in Bemis’ lab, currently a doctoral student at the Virginia Institute of Marine Science, is the paper’s first author.