Shells with holes - ID both shell and animal that made them

[bellzeybubba]

Hello, I'm hoping you folks can help me find the resources I need.

My son (2nd grade) wants to do a Science Fair project about some of the sea shells he collected this summer in Myrtle Beach, South Carolina, USA.  What interested him the most was that some shells were full of holes, for his project he wants to do a presentation of how the shell is formed and how the holes are made.

He picked the shells that had the most holes in them, so none of them are complete.  I'm pretty sure the dark ones are oyster shells and I think the other ones could be clams (white/grey bands, fairly large, thick pieces), how could I confirm or at least get a rough identification?  Most guides I've seen online are for intact shells (of course) but none seem to include oysters.

Also from searching around online we know that the holes are called by bioerosion from sea animals like boring sponges, but I haven't found anything that will help us identify which animal from the look of the holes.  Any ideas where to look?  If we can't find it he'll just do a general presentation about bioeroders, but if we can do it he'd love to have each of his specimens identified.

Thanks for any help <img src="images/smiley/smile.gif" alt="" border="0" />

[paul monfils]

A scattering of small holes over an area is usually caused by boring sponges.  A single hole penetrating all the way through the shell, especially if located near the hinge area, is usually caused by a carnivorous snail of some kind.  Smaller holes with straight sides are produced by oyster drills.  Larger holes with beveled edges are produced by moon snails.  Small holes that lead into winding tunnels in the shell can be produced either by boring worms or by boring bivalve mollusks.  If you can provide a few fairly clear closeup pictures, we can probably give you further information both about the shells and the holes.

[dave r]

Is there any chance of seeing some photos? The holes could have been made by any of a number of animals and a look may give us some idea. It may also help identify the shells themselves.
Dave

[bellzeybubba]

Pictures are coming... just took them and now we're resizing... thanks for all the help <img src="images/smiley/smile.gif" alt="" border="0" />

[bellzeybubba]

Ok, here goes.  In pairs, one for the top, one for the bottom.
Shell 1:
<img src="http://ellzey.org/wordpress/wp-content/uploads/2009/10/2bottom.jpg" alt="http://ellzey.org/wordpress/wp-content/uploads/2009/10/2bottom.jpg" style="border:0" />
<img src="http://ellzey.org/wordpress/wp-content/uploads/2009/10/2top.jpg" alt="http://ellzey.org/wordpress/wp-content/uploads/2009/10/2top.jpg" style="border:0" />
Shell 2:
<img src="http://ellzey.org/wordpress/wp-content/uploads/2009/10/3top.jpg" alt="http://ellzey.org/wordpress/wp-content/uploads/2009/10/3top.jpg" style="border:0" />
<img src="http://ellzey.org/wordpress/wp-content/uploads/2009/10/3bottom.jpg" alt="http://ellzey.org/wordpress/wp-content/uploads/2009/10/3bottom.jpg" style="border:0" />
more in next post...

[bellzeybubba]

Shell 3:
<img src="http://ellzey.org/wordpress/wp-content/uploads/2009/10/4top.jpg" alt="http://ellzey.org/wordpress/wp-content/uploads/2009/10/4top.jpg" style="border:0" />
<img src="http://ellzey.org/wordpress/wp-content/uploads/2009/10/4top.jpg" alt="http://ellzey.org/wordpress/wp-content/uploads/2009/10/4top.jpg" style="border:0" />
Shell 4:
<img src="http://ellzey.org/wordpress/wp-content/uploads/2009/10/5top.jpg" alt="http://ellzey.org/wordpress/wp-content/uploads/2009/10/5top.jpg" style="border:0" />
<img src="http://ellzey.org/wordpress/wp-content/uploads/2009/10/5bottom.jpg" alt="http://ellzey.org/wordpress/wp-content/uploads/2009/10/5bottom.jpg" style="border:0" />
few more...

[bellzeybubba]

Shell 5:
<img src="http://ellzey.org/wordpress/wp-content/uploads/2009/10/8bottom.jpg" alt="http://ellzey.org/wordpress/wp-content/uploads/2009/10/8bottom.jpg" style="border:0" />
<img src="http://ellzey.org/wordpress/wp-content/uploads/2009/10/8top.jpg" alt="http://ellzey.org/wordpress/wp-content/uploads/2009/10/8top.jpg" style="border:0" />
Shell 6:
<img src="http://ellzey.org/wordpress/wp-content/uploads/2009/10/9bottom.jpg" alt="http://ellzey.org/wordpress/wp-content/uploads/2009/10/9bottom.jpg" style="border:0" />
<img src="http://ellzey.org/wordpress/wp-content/uploads/2009/10/9top.jpg" alt="http://ellzey.org/wordpress/wp-content/uploads/2009/10/9top.jpg" style="border:0" />

Like I said, they're pretty beat up, but these are the ones the boy picked that he wanted to learn more about!

[paul monfils]

Hi.  Good pictures!  #1 is, as you said, an oyster, the Common Atlantic Oyster or Virginia Oyster, Crassostrea virginica.  The rest of them are pieces of the Atlantic Quahog, Mercenaria mercenaria, as you said, a clam.  #1 and #4 are very typical examples of damage from the boring sponge, Cliona celata.  #5 and #6 I believe show more advanced Cliona damage, but I think there may be other borings present as well, probably from annelid worms.  #2 and #3 do not look typical of Cliona damage and I think the damage on these looks more like worm borings.  <span class="petit">--Last edited by Paul Monfils on 2009-10-07 21:08:42 --</span>

[bellzeybubba]

Wow, thank you so much for your help, this is great!  He's going to put your name & this site as a reference on his project.  Again thank you, we really appreciate it <img src="images/smiley/smile.gif" alt="" border="0" />