Saturday, April 28, 2012

Land Planarians in Portland? Who Knew!?

Oregon State University, like many land grant Universities, has an Ask an Expert service.  Through this service, anyone can submit a question on just about any topic: gardening, nutrition, agriculture, livestock, landscaping, pesticides, hens, food safety . . . . you get the picture.  Your question is then answered by an Oregon State University faculty member, or in some cases, expert Master Gardener volunteers.

Many people submit photos of insects, arthropods or other invertebrates that they would like us to identify.  I have quite a bit of training in entomology (M.S. and Ph.D. from the University of Maryland and post-doctoral research at UC Davis).  I'm not usually stumped.  But this week, a question referred to me by one of our most prolific Ask an Expert volunteers left me perplexed.

What is this?

I had no idea!

The picture is in 2 frames.  The one on the left shows the beginning of a 'nob'.  The one of the right shows the same critter, a few moments later.  The photo was taken in Multnomah County (photo posted with permission of the person who submitted the question).

Luckily, I'm not the only person at Oregon State University who can field such questions.  The esteemed Dr. George Poinar, a courtesy professor of Entomology at Oregon State University, provided the answer.

"I think it is a land planarium of the family Geoplanidae.  Very little is known about them, but they suddenly appear and then are gone.  The structure sticking down on the ventral (bottom) side would be the pharynx.  They are predaceous, eating earthworms and snails. The systematics (biological classification) is complicated, and photos are difficult to find on the web."

Poinar then added further details.

"The Geoplanidae is a large, diverse family with several subfamilies.  Check the images of the members and the 6 tribes of the Rynchodeminae. Some of these are round in cross-section.  It would be nice if someone did a synopsis of this group along the Western coast."

Since so little is known about this group, and so few photos are posted on the web, I wanted to get this information posted.  It's a real treat to glimpse something so rare and fleeting in our own backyard.  

By the way, Dr. Poinar's extraction of 130 million old DNA from insects preserved in amber was the inspiration for Micheal Crichton's novel turned movie, Jurassic Park!


  1. I have found them in my yard west of Eugene but never in increasing numbers. The ones I have are darker in color but definitely planerium (or is it planeria?).

  2. I've never seen one! It feels so wrong, but I have this urge to find one, so that I can slice it from its head half way down its body. I can't think of planeria, without going back to high school biology labs. We'd slice a planerium half way down it's center line, to see it regenerate two new heads! See for more details.

    1. Ah, yes. So long ago. I remember being a lab assistant in Mr. Green's biology class when we were playing with planeria.

  3. Oh Gail! Fun post, but a 2-headed planaria is creepy, even for me. I actually had one brought into Lane Extension many years ago and it took a while to figure that one out! I think it eventually ended up at OSU.
    Isn't nature fabulous!


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