Friday, April 11, 2008

Snails, striped, peeled and drilled

I'ts amazing how learning something new opens our eyes. A few days ago, Aydin Örstan, on Snail's Tales, wrote about peeled sea snails. I had seen these, but, as so often happens, didn't know what I was looking at; to me, they were just broken snails, pretty, but of no other interest.

I know better, now. Thanks to Aydin.

Boundary Bay beach has been taken over by millions (billions, trillions?) of Batilaria attramentaria, the invasive Japanese mud snail. Laurie photographed them a couple of years ago; mottled, brownish, sharply conical snails up to about 4 cm. long.

Photo from my Flickr page.

Another Batilaria attramentaria. Photo from NOAA photo library.

A couple of days ago, on the north end of the beach, I noticed that the snails were different; some were smaller, and elegant in stark black and white stripes, others wore some combination of the usual pattern with black and white. I took a few photos, to look at later.

Quite a variety.

I don't know if these are the same species, or a different one; Googling Batillaria images, I found several black and white ones, including a B. attramentaria. But these are smaller, besides. The large one I brought home is barely 2 cm.

At home, when I blew the photos up to full size, I noticed something else; peeling.

Aren't they pretty?

The snail at lower left is missing the outer shell on the bottom loop. The brown and white little one, second from the right, seems to be also missing a segment.

A few more. Three are "peeled".

And here's one that's drilled; see the hole?

Aydin explains that crabs peel back the fragile shells of small snails to get at the animal inside. I asked how big the snails have to get before they are safe; he wasn't sure. Ridges and bumps on the shell serve as a protection, but these Batillaria are fairly smooth. And small; I have seen a few about 4 cm. long, but most are closer to half that.

The drilled hole may have been made by a limpet, another snail, or any of a number of small sea creatures, using a raspy tongue, or "radula". (See Aydin's comment, below.)

It's a dog-eat-dog world out there.

Molted crab shell. Nice big pinchers for cracking snail shells.



  1. I don't think limpets drill holes. Certain gastropods & octopuses are the only predatory hole drillers that I know of. Gastropod holes usually have uniform edges, whle those of octopuses are more jagged.

  2. Thank you. I got that tidbit from one of the websites that I read. I should have double-checked it before I used it.

    Thanks for the correction.


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