Boring Clams

If you walk on the beach in Monterey you will find stones with holes in them. I always knew them to be caused by 'boring clams' and I'd seen pictures of people holding up pointed clam shells but this idea started to bother me. I can imagine holding a clam shell and twisting it against some sandstone to bore a hole but I couldn't imagine how a clam would do this. They have no leverage.

I did some poking around and discovered they actually grow their shell into the rock. They have a foot that grasps the surface and they wiggle until it gouges the rock and then grow another layer on their shell. They physically grow as they burrow, so the holes are often larger on the inside than the opening. I'm still unclear about the actual mechanics of a clam holding onto a rock, siphoning food from one end while drilling into the rock with the other and unfortunately all the images online don't help..

Imagine a clam. It has two oblong shells held together with a meaty body. Where do you put a clams 'foot' to allow it to hold the pointed tip of it's shell against a rock surface? Maybe it's like a mussel with it's saltwater adhesive and threads?

One site said they have some mysterious ability to tell when they're burrowing too close to another clam and will adjust their excavation.

I didn't learn much about the mechanics but now I've shared this mystery with you. Please go become a marine biologist so you can answer this question for me, thanks.

posted by na on September 4, 2021 11:19