Just how sharp are sharks’ teeth? To find out, biologists at the University of Washington glued teeth from four shark species onto power saw blades. The scientists used the blades to slice through chunks of raw salmon to see how well the different teeth cut. 

Teeth from the tiger, sandbar, and silky sharks sliced through the fish “like butter” but dulled quickly, says evolutionary biologist Stacy Farina. The sixgill shark’s teeth didn’t cut as well but wore down more slowly. 

There might be a trade-off between a tooth’s cutting ability and its strength. “Sharks replace their teeth pretty often,” says Farina. Those with blunter teeth—like the sixgill—may not have to regrow their teeth as frequently, she says.