Tuesday, August 2, 2011

"Death by radula" OR "An introduction to predatory snails of the PNW"

Urosalpinx cinerea having their way with a Crassostrea gigas
One of the things I really enjoy about what I do is getting to talk about killer snails.  Those of us who garden are, of course, lamentably familiar with the destruction wreaked by terrestrial snails and slugs.  But, by and large, the majority of the (non-marine) folks who ask about my research are surprised to learn that snails can be voracious predators of flesh.  My favorite part of this exchange is always watching how people react to a description of death by radula, which, even without the, shall we say, vibrant descriptors and pantomime I typically provide, is actually pretty graphic.  

In the most antiseptic terms, death by radula goes as follows: Snails (and many other Mollusks) have a chitinous feeding structure called a radula, something like a tongue covered with very hard teeth that is adapted to their particular diet.  Predatory snails use this as a drilling structure.  They secrete an acid to soften the calcareous shell of bivalves, barnacles, and yes, their friends if need be, and scrape away softened shell with their radulas, until they have pierced the shell (see below). This has earned the snail depicted above the fitting common name of Oyster Drill. 
Oyster drill (Ocinebrina inornata) hole in Crassostrea gigas shell.

Then they suckouttheguts! 

There are of course, other feeding strategies for predatory snails (see the Conus genus hunt...and be astounded! Moon snails cannibalize their buddies by smothering them!  Come at me, bro!). But my point is this: reactions to this imagery can typically be categorized as either grossed out, or fired up.  No one is completely unmoved by the thought of being an oyster in your lil' shell and knowing, even limited by your relatively undeveloped nervous system, that there is a snail drilling into your shell WITH ACID, and that it will SUCK YOUR GUTS OUT when it gets through.  And there is NOTHING YOU CAN DO TO STOP IT.  

The fired up among us are my kindred spirits.  This blog aims to be a celebration of the little gems of insight on the natural world that get us all fired up, the moments of enlightenment that change the way we look at the world around us, and make us grateful that we are not oysters.

Rah Rah Radula

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