Saturday, January 5, 2013

Learning from Moon Snails

My daughter found this tiny (deceased) moon snail while walking on the beach with her Grandma.  We knew it had died because while the animal was still in the shell, it was floating and didn't retract when touched.  So we had a rare opportunity to look at it more and learn from the moon snail!

Tiny Moon Snail
I first heard of moon snails on my BPro kayaking trip to British Columbia.  We used a large moon snail shell as a "talking stick" for our opening and closing rituals, and one of the amazing biologists we kayaked with showed us the architectural egg casing that the moon snail creates using sand, seawater, and the mucus it secretes.  So when my daughter found this one, I got excited.  I showed her its foot and how it has tiny microscopic serrations that it uses to drill into clam shells, creating the little holes in the shells we used to make a necklace.
Tiny Moon Snail
We looked at the shell's gorgeous spiral shape and purplish color, the spiral a result of how it grows larger and builds its shell.  We think that the snail died because the protective cover on its foot got jammed on a slightly damaged shell edge and couldn't retract.  But this creature's misfortune gave us a chance to look at it closer.  And as the creature dried up and fell out of its shell, we got to examine it in greater detail.

  • It appears to be composed of three connected parts:  the serrated foot (radula) for drilling into shells, the protected cover shield, and the arm attached to its shell.  The foot and the cover shield form the mantle and can extend to cover the shell, if needed.
  • The cover shield became translucent like a thin piece of amber and was quite delicate.  
  • As it dried, the serrated edge of the foot became more obvious and pointed.  I researched this a bit and it turns out that the moon snail secretes an acid to soften its prey's shell and then uses this serrated tongue to drill into the shell.  
  • When the snail dies, its shell is usually quickly taken over by a hermit crab.

It's amazing to me to think about how nature can create serrated drilling instruments in the sea using abundant materials and great design.


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