Friday, November 9, 2012

Ice Worms. Yes, They're Real!!!



   
 That’s what Ben Lee told me years ago when I looked at him like it was April Fool’s Day. Although I think he said, “damn it, they’re real!,” Ben was looking for an organism that would allow him to spend time in the mountains AND do some summer research. Ice worms are annelids, in the same group as earthworms, and endemic to the coastal mountain glaciers from central Oregon to south-central Alaska. These little denizens of the snow and ice are small – usually no more than an inch long, and 1-2 mm wide.  They look like a thick-ish hair on the snow surface, or a piece of stout, fruticose (gotta love that word!) lichen. Ice worms typically emerge onto the glacial surface to feed on algae and bacteria in the late afternoon and will stay out until the surface starts freezing over. On warm nights they party all night.  

 Ben Lee with ice worms.

     Ice worm distribution is likely limited by their narrow temperature tolerance – they survive between about -6 - +6 C.  Coastal glaciers (in the Olympics, Cascades and up the coastal ranges of BC and Alaska) are “temperate” glaciers, meaning that their internal temperature always hovers around freezing.  We don’t find ice worms in glaciers on the Rockies, presumably because it gets too cold during the winter, or the prolonged cold season leads to a lack of food; we don’t find them much above 10,000’ on Mt Rainier, probably for the same reasons. 


 photo by N. Takeuchi


      Ben and I examined the population genetic structure of ice worms in the Olympic Mountains. Previous work done by Paula Hartzell, Dan Shain and colleagues showed that there were two distinct evolutionary lineages, a northern lineage in Alaska (and probably into BC) and southern lineage that ranged from somewhere in BC to Sisters, Oregon. We predicted that the Olympic worms would be most closely related to the Cascade Mountain (southern) worms. But when Ben started getting his DNA sequencing results, all of the first worms examined (from the Olympics east of the Elwha and Mt. Comox on Vancouver Island) belonged to the northern lineage. And then the story got more convoluted.  On the last collecting trip of the year, Ben collected worms from Mt Olympus and Mt Carrie (west of the Elwha drainage). The worms in those collections were a mixture of worms from the southern and northern lineages! 

  Ali Garel and Peter Wimberger collecting ice worms. Photo: Holden Sapp    

    That leads to a number of obvious questions:  1)  how did the northern worms get to Vancouver Island and the Olympics?  2)  Why do both lineages coexist in the western Olympic Mountain glaciers?, and 3) Do the northern and southern worms make wormbabies together?  Think about it and I’ll post our thoughts next week!

To watch an old clip of Ben Lee and me on Oregon Field Guide:

Peter Wimberger

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