Monday, January 23, 2012

Salt Marsh Snails

I've been meaning to write this post for a while but I hand't managed to figure out what the upshot or the moral of this story was. I think I figured it out so here goes:

Back in the fall I led a trip with some Boston Public teachers and their students to a local salt marsh. I visited the classrooms before and after the trip to support the students' learning and the teachers' goals (and their learning as well).

There are two main types of snails you see in Northeast salt marshes, littorina littorea, the common periwinkle and melampus coffeus, the coffee bean snail. Littorina is marine, it breathes water and spends most of its time under water while melampus is terrestrial, it breathes air and while it lives right on the edges of tidal creeks it is never seen in the water. When the tide moves melampus will react by climbing a stalk of marsh grass to avoid being drowned.

During my trip back to the classroom with one of the teachers I found she had a book about salt marshes and I had a little down time before I met the students so I decided to flip through the book. I found a photograph of what looked like littorina climbing up marsh grass with a description that periwinkles climbed up to avoid drowning. "Hrmm..." I thought. I knew that periwinkles were marine and I had never seen this behavior before. Littorina tends to eat algae and not marsh grass so I thought, "maybe it's feeding, but I doubt it." I talked to the teacher who had used that image during one of her lessons. "I'm really not sure what's going on in that image, but I'll look into it."

So I did and I discovered that it was indeed littorina in the photo, just not littorina littorea. It was another salt marsh snail (in fact common name, salt marsh periwinkle), littorina irrorata. These periwinkles do feed preferentially on marsh grass and not algae and I quickly turned up a number of similar images of littorina irrorata climbing up grass to feed. Apparently this species can be found as far north as Massachusetts but is more common slightly further south so I was not as familiar with this snail.

At first I thought this story was about being careful about what you read, especially when it is written by non-scientists (like me!) and to fact check your sources. But that's an old story and most of us have heard dozens like it. I realized that this story really held a moral for me and not the teacher. I didn't realize this because I instinctively acted on the moral, I did the research, figured out what the image was all about and reported back to let her know what I had found. I didn't just throw up my hands and say "Oh, it's probably just l. littorina doing something weird I've never seen before."

So I think the moral is this: it's most important to make sure you know what you're talking about when you are the specialist. As an ambassador for robust inquiry science education it is even more imperative for me to assume I don't know everything and that when I see something that doesn't fit my preconceptions it is even more important for me to do the research so I can reconcile the new information. So I encourage all of you who are science educators in any respect to always be on guard, especially when you think you know exactly what you're talking about. You may be surprised that you don't...and you might actually learn something.

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