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November 13, 2013

Predation

holeshell.jpg

Here’s a gorgeous image of a clamshell fossil found near the city of Huelva in Spain. The city lies on the Atlantic coastline and has a variety of fossil-bearing layers from the Pliocene epoch.

This looks like a common clamshell of the sort you’d find on any beach in the world, but take a look at the hole in the shell. It’s smooth, it appears in almost a random spot, and it penetrates through the entire shell.

That hole is how this organism died; it was a victim of predation. In the ocean, predator organisms like the nautilus latch on to shells of clams and begin dissolving their way through. The clams may have some defenses, so oftentimes bores won’t make it through the entire shell, but in this case the predator got the whole way through and had dinner.

These types of attacks often lead to an evolutionary arms race. Clams may start developing thicker shells or ridges on their shells that make it harder for the attacking organism to penetrate, leading to the many varieties of shells you’ll find on an ordinary beach today. Next time you’re there, take a look for the shells with holes going the entire way through; when you find one, you’ve found one that was dinner for a predator. - - Clam @ The Earth Story

Posted by gerardvanderleun at November 13, 2013 8:20 AM. This is an entry on the sideblog of American Digest: Check it out.

Your Say

And here I thought the hole was drilled by a person making a necklace.

Posted by: Potsie at November 13, 2013 9:05 AM

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