WIKIMEDIA, GLENN WILLIAMSThe function of the single, spiraling tusk of the narwhal, a marine mammal that lives in the Arctic, has captured the imagination of mariners and marine biologists alike. Is it an ice pick? A mate attractor? A paper published in The Anatomical Record today (March 18) indicates that it acts like a long, pointy antenna, picking up signals from the animal’s environment.
“It takes a tremendous amount of energy and devotion to get that thing to grow,” Harvard University’s Martin Nweeia, the lead author of the study, told Wired. “To expend that much energy in such a harsh environment—there has to be a pretty compelling reason to do it.”
The tusk is actually an overgrown, twisted front tooth. In its paper, Nweeia’s group showed that the innervated tooth is porous. When the researchers dipped the tusks of captured narwhals into waters of varying salinity, the whales’ heart rates changed: higher salinities resulted in a faster beat. “This is the first time that someone has discovered sensory function [for the tusk] and has the science to show it,” Nweeia ...
