Skip to Main Content

Critter Chemistry

February 3, 2003

Sharks' Gel Behaves Like Semiconductor

Sophie Wilkinson

"There could be some fascinating molecular electronics going on in there," declares Brandon R. Brown, assistant physics professor at the University of San Francisco. He's referring to a gel-filled organ on a shark's snout that it uses to find fish prey and to orient itself.


Brown has had sharks on his mind for years. When he was a graduate student, an acquaintance told him that sharks could detect electric fields. His friend surmised that sharks might have superconductors in their heads. "I thought that was crazy," Brown says. Nevertheless, the idea stuck in his mind, and Brown began studying shark gel a couple of years ago.

First, he found that the gel's electrical properties vary with temperature. Semiconductors share that behavior, and they also exhibit a large thermoelectric effect--generating electricity when the ends of the semiconductor are exposed to different temperatures. Brown has now determined that shark gel shares this property as well [Nature, 421, 495 (2003)].

The gel, which resembles Jell-O, consists primarily of water, combined with some large sulfated glycoproteins and sodium, calcium, chloride, and potassium ions. Brown is going to mix up several synthetic gels to compare their behavior to shark gel. "Maybe any organic gel made of these big glycoproteins with dissolved salts will have these properties," he says. "But maybe evolution has fine-tuned the exact size and electronic interactions of these huge molecules."

Chemical & Engineering News
ISSN 0009-2347
Copyright © 2010 American Chemical Society