Full Version: Found on the beaches of South Padre Island, Texas
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I am not a shell collector by any means but I just returned from a trip to South Padre Island, Texas.  I found these shell pieces and I was just drawn to them for some reason.  I would like to know what they are.  I found tons of these pieces and some almost whole shells.  They are very thick.  Any information you could give me would be appreciated.

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Hi Sarabeth,

These are shells of the Southern Quahog, scientific name Mercenaria campechiensis.  The name "quahog" is of Indian (Native American) origin. The name "Mercenaria" is a reference to money, like the English word "mercenary".  It is so called because these shells were used by early Native Americans to make "wampum" beads - which they used as money.  This shell belongs to a family of molluscs called Veneridae, or in common terms, venus clams.

<a href="" target="_blank"><!-- m --><a class="postlink" href=""></a><!-- m --></a>  <span class="petit">--Last edited by Paul Monfils on 2009-06-29 16:43:24 --</span>
Actually the shells in the linked photos appear to be average size specimens, probably not too thick and heavy yet.  When they get bigger, 4 to 5 inches, they get much thicker and heavier.  A large live specimen can weigh more than a pound.
Great!  Thanks so much!  I actually did see that page that you linked before I found this website and I wondered.  I just didn't know for sure because I couldn't tell the thickness of the shells by the photo.  I have never seen shells so thick before and I just love how the pieces are so smooth and the edges rounded off...not to mention the beautiful colors.  

Now my container of shell pieces has a little story behind it!  Thanks so much!
Interesting. I have very similar one from that place that I named Rangia cuneata. I guess I will have to update my data.
Hi Pierre,
Rangia cuneata is found in that general area, but it is actually a brackish water shell not likely to be found on a true ocean beach.  It is only about 2 inches in length, is wider than it is tall, bluntly pointed at one end, and typically has a dark periostracum.  Also, since it is in the family Mactridae, its hinge structure is quite different from that of Veneridae.
Thanks Paul,
Below is the shell I previously misidentified (61mm from Texas)

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Around Padre Island (and almost all along TX coast), large brackish water areas stand behind the beach. I guess some shells can drift out of the lagunas and get washed on the ocean side.

Hi Pierre,

You may not have misidentified this. Your shell is definitely in the family Mactridae, and could be Rangia, though I am not certain of the species. It definitely is not the same shell posted above by Sarabeth, which is in the family Veneridae. Note the large smooth depressed area in the hinge area of your shell.  This is called the chondrophore, and is typical of Mactridae. Compare this to the hinge structure of the shell Sarabeth posted.