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Sunday, December 20, 2015

Calcareous


A pheasant snail (Eulithidium pulloides), grazing along a blade of surfgrass (Phyllospadix sp.).  I first showed pictures of the shells of these snails in April 2014, but I haven't shown the entire animal yet.  (They're hard to find because they're quite small only a few millimeters long.)

One of the interesting characteristics of this species is its operculum (or "trapdoor").  In most marine snails, the operculum is made of a protein material (think about a moon snail operculum).  But in some species, including these pheasant snails, the operculum is harder and made of calcium carbonate.  

See below for a close-up of the white, calcareous operculum:


Can you think of reasons why it might be helpful for a snail to have a calcareous operculum?  (One possibility is mentioned at the bottom of this post.)

If you're interested in finding a pheasant snail, try searching the bases of surfgrass clumps during a good low tide.  


P.S. Calcified opercula are thought to be a defense against predators.

4 comments:

Anonymous said...

Wow. They are beautiful Jackie. Thanks for sharing.

Alice Chan said...

What a lovely critter!

Jackie Sones said...

I'm so glad to hear others appreciating this little beauty! It's one of my favorite local snails. Thanks for the feedback!

:) Jackie

cricket said...

i love your blog and learn so much from it!