Wednesday, October 17, 2012

Friend or Foe?

Google is an amazing tool. You can use it to learn about almost anything. I was moving pots in the yard yesterday and found a bizarre creature curled up under one of the saucers. At first I thought it was a tiny snake. I've found them in the yard before, in about the same location. But this was slimy. I thought for a while that it was just a long worm, but as I looked more closely, I realized that it was much longer than a worm, striped, flat and not segmented, and the most unusual part--it had a head that looked like a hammer or spade. It moved very gracefully and reminded me of a slug. A really long slug. Probably 6 inches long uncoiled. Really weird critter. I ran in the house, grabbed the camera, and shot a few pictures.

"Flat Head Worm"

I carefully moved the wormy thing to a new, safe location, and covered it with a dish to keep it from being squashed. Then I turned to the computer and Google to figure out what on earth I'd just found. It's always exciting to discover a new animal in your neighborhood! I didn't know where to start, so I just described it. I typed in "flat head worm". Bingo! I could see right away from the images that I'd found my animal. Unfortunately, as I read on, I learned that it wasn't good. I had found a Land Planarian or Flatworm (Bipalium kewense). Almost every article I read said that I should kill it right  away because they are invaders from Asia and they dine exclusively on earthworms. I was so disappointed. I really like this fascinating worm. But now that I know what it does, there's no way I can let it outside again. I'm not good at killing, either, so I'm considering keeping it as a pet for a couple of weeks.
My Pet Planarian, exploring

So what's the big deal? Who cares if it eats worms? Well, just like the Dung Beetles from my last post, earthworms are extremely important decomposers. They eat rotting vegetation and turn it into rich soil. They crawl through the dirt, aerating and supplementing with their waste, or castings. If we didn't have earthworms, we'd be buried in plant debris. Earthworms are essential, keystone species that many other organisms and systems depend on. But the funny thing about our earthworms is that they are not all native to North America. Those night-crawlers we use for fishing? Not native. One article that I read said that 60 percent of the earthworms in North America are not native, coming from Asia and Europe, brought here in the horticulture trade starting in the 1600's. There is a fascinating article from National Geographic about the Jamestown Colony which talks about the impact of the importation of non-native earthworms and other species. These non-native earthworms are also decomposers, but they are so numerous and voracious that they eat too much plant debris and dig it deeper into the ground. Some plants and trees need more leaf debris for slow leaching of the nutrients and ground cover and cannot extract nutrients from the soil if it is too deep. So the non-native earthworms may be harming and changing our ecosystems in myriad ways. Now that I think about it, maybe it's a good thing if the Flatworm is added to the mix. Maybe the Planarians can keep the non-native earthworms in check, too. Who knows? Anyway, who am I to point fingers and decide which species can stay in Florida?  I was born in Utah.  Once you start messing with the natural order of things, there is so much moral ambiguity that I get foggy. I think this time I'm going to err on the side of kindness and I'll let my pet Planarian go. I'm not all that keen on killing animals, even rotten ones (like cockroaches) and I've never seen one before, so they are not running roughshod over my yard. Yet. (Famous last words.)


  1. Maybe you should eat it? Maybe take it to Utah?
    Very good description. Glad you could identify it! Great photos !

    1. Doesn't look too tasty. Pretty slimy! Thanks for reading!

  2. THANKS!!!I found one under a rock that was inside a potted plant. There were also many cockroaches hidden under other rocks in the same potted plant, as well as numerous earthworms. I killed it with little fanfare and only a slight tinge of moral ambiguity. I live in Bakersfield, CA. May my earthworms live long and prosper in my garden.

  3. Glad Google and I could help. It's funny--with invasive exotic plants I have no qualms. Out they go. But with animals I have a much harder time, even though they are just as harmful. Thanks for reading!