This is the final post in a series by Associate Curator of Invertebrate Zoology Janet R. Voight following her expedition to Norway. There, she and colleagues searched for a wood-boring clam, Xylophaga dorsalis, to study its, well, poo. Read the first post to explore the full journey.
After a week of periodically flushing the chimneys off my little clams, I can still smell the sulfide from the wood as it sits in its aquarium. Over time, I’ve counted up to 25 fecal chimneys, all from tiny Xylophaga dorsalis. As their siphons emerge (I use the phone’s camera to magnify them), the fringes on the siphon help me identify the species. When it comes to the questions that motivated the trip—what does the fecal chimney do and why do the animals go to such efforts to make one?—I hate to admit that I still don’t know. Without animals that were big enough to manipulate, I couldn’t do all my planned experiments. However, there is always a plan B in science (if you allow for it). Considering the live animals, the museum specimens, and fresh samples, I hope the chemical and microbiological studies I planned will be able to test the hypothesis of whether these animals use chemosynthesis.
But now I have new questions: first, why does the chimney extend so far above the wood? I suspect that it forms a barrier between the animal and the sulfide-rich habitat, essentially sealing it. But why are the sensory fringes and the white spots on the siphon restricted to the part of the siphon that is the farthest from the wood, and even above the chimney? If they are sensing sulfide in the wood, shouldn’t they be near the wood?
Given that I didn’t get the firm answers I wanted (yet), has it been a good trip? Yes, we accomplished what we set out to do, a goal we were told would be all but impossible. Many people helped us, regardless of their doubts about the project. Henrik Glenner, who fed us on our first night in Norway when we had no food, provided help in many other ways, from assisting with the research boat to letting me study material he collected in more distant fjords. Jon from the Bergen Museum did us a huge favor by making that material available for me to study at the marine station. I provided identifications and, most importantly, took tissue samples. Audrey Geffen, professor of Biology at the University of Bergen and an alumna of the University of Michigan, was a great help in so many ways! Meeting her was like finding a long-lost sister. The captain and crew of the research boat (although I’m sure they thought us crazy) were as delighted as could be when I told them we had collected live animals! Tomas and Mette, the staff at the marine station, made everything work, and their company made our stay pleasant. Professor Torleiv Brattegard helped us figure out Norwegian food, provided information on the physical characteristics of the fjords, helped us select where to trawl with the research vessel, and allowed me to highlight his work.
We’re not looking forward to those long flights back, but it’s time for us to go home. To those of you who have followed these blog posts, thank you (I know they were too long). I trust you know that you weren’t really reading about clam feces, but about curiosity and science, and how sometimes looking into the strangest things opens doors to new avenues of investigation. When you start to ask why, you never know what you will find.
Funding for this project was provided by the Robert A. Pritzker Center for Meteoritics and Polar Studies established by a grant from the Tawani Foundation.