I have collected some shells and pieces of shells that are full of holes or have crazy lines etched in the top. Sometime a shell will have a perfect hole all the way through it, just as if it was meant to be hung on a wire to make a pretty necklace.
I never knew what caused these phenomenons until I read about “Shell Wars” in my new reference book, “Florida’s Living Beaches, A Guide For the Curious Beachcomber” (affiliate link to Amazon), by Blair and Don Witherington. In the mollusk section of the book they explain how some gastropods will bore holes through the shells of others to feed on them. In doing so, they leave a hole, or sometimes lots of holes as in the case of boring sponges that use acid to digest shells and actually leave them looking like a sponge – full of holes.
How Are The Bore Holes Made
Meat eating mollusks will eat other mollusks and one way they do that is to bore a hole into the shell and suck out the snail inside.
With their tongue, or radula, they create the hole with the help of enzymes from their own body which soften the shell. They use their radula as a drill, and make the hole.
This is why some shells look like a hole was drilled perfectly into the top. That sea snail was killed by another snail.
Considering Sea Snails, There is Lots to Learn
When you find a beautiful shell on the beach, do you ever think about the creature that used to live inside? They are interesting organisms and the shell homes they create are even more so. Each mollusk makes it’s own type of shell, and within those varieties can be more varieties. Each seashell is unique, which is why we love collecting them so much.
Now that I have a boat, and can get out to the islands along the Indian River waterway, I’m constantly looking for unique mollusks and their seashells. Sometimes I even get to find a living shell like this huge horse conch and beautiful fighting conch.
I see plenty of empty shells with weird markings too, but now I know why they are there.