Grad Publication: Stephanie Crofts

      There is an arms race between hard-shelled prey and their predators, an arms race that has been going on for quite some time now.  Most of the work that has been done on this system has focused on how shelled organisms avoid being eaten: they invade new niches, they grow spines, and overall just make themselves unappetizing.  But what about the predators?

      In the paper that my advisor, Adam Summers, and I just published, we asked the question: why are durophagous teeth (teeth that crush hard-prey items) shaped the way they are?   You would think this would be pretty straightforward, especially looking through the literature where most hard-prey crushing teeth are described in generally similar terms. They’re molariform, or rounded, or bulbous--but that doesn’t really get at the diversity.  In fact, crushing teeth can also be flat, concave, or even cusped!  So, to see if some teeth break shells better than others, we made aluminum tooth models and used them to crush some very special shells. 

      Instead of using actual snail shells, which come in different sizes, can have different material properties, and usually come with a snail inside them, we used a 3D printer to make our shells.  Modeled on local intertidal snails from Friday Harbor Labs, the 3D printed shells allowed us to eliminate variation due to natural history, while still maintaining all of the external and internal shell anatomy.  It also allowed us to make two very differently sized snails the same size.  Then we used a materials testing machine to crush the 3D printed shells and measured the force different theoretical tooth shapes needed to break them.   We found that flat teeth and cupped teeth aren’t as good at breaking hard prey as pointier teeth are.  But, pointed teeth are at a greater risk of being broken by the prey. 


      Unfortunately, we don’t see many hard-prey crushing teeth with long pointy cusps… they break!  Next step: figure out which shapes break less than others.

      Check out the video to see the crush in action! (Be patient...)

And here's the paper!

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