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Wandering broadhead planarian, or "landchovy" Bipalium adventitium

I first encountered this predatory flatworm while doing a survey of animal species in the Olmsted Woods. I did a little research, corresponded with an expert, and found that this terrestrial planarian was a relatively recent introduction from Southeast Asia (accidentally, with tropical plants), and that it preyed on earthworms. At the time it was believed that Massachusetts was the northernmost range of this creature, but I have since heard from at least one observer from Vermont.

I am amused that a specialized predator of earthworms has arrived in New England. It was only about 400 years ago that earthworms themselves were introduced to our glacier-scrubbed landscape. It's hard to know what an earthworm-free New England would look like, but farming probably would be different and more challenging. For the time being, the landchovy doesn't look like it's going to wipe earthworms out. It does make me wonder if there's a predator that specializes in house sparrows that we could bring in.

I first posted about this species here, following up here and here. The comment threads to those posts include reports of citizen scientists and alarmed homeowners all over the eastern United States.
I occasionally get comments to old entries, and recently I've gotten two to my 365 urban species post about the wandering broadhead planarian, affectionately known as the "landchovy" by my readers. This terrestrial flatworm is an predator of earthworms, an alien native to Indonesia or thereabouts, accidentally introduced into North America in exotic plants(probably). It was first detected in the middle of the continent (I want to say the Chicago area, but I forget exactly) and has spread, or been introduced to, both coasts and just about everywhere in between. I found several in Boston, which may be about the northernmost extent of their range on the east coast.

More, so much moreCollapse )

Photographs by cottonmanifesto.

Urban species #291: Terrestrial flatworm Bipalium adventitium

I'm making a more conjectural species identification this time than I usually do, if you can believe that. Bipalium adventitium is a species known to be in the United States from Illinois to New York, and spreading. I'm still waiting to hear from someone at the Harvard Museum of Comparative Zoology to see if an identification to species is even possible. This type of animal I have seen exactly three times, each time under debris in the wooded part of Olmsted Park in Boston. What's reasonably certain is that this is an exotic animal, most likely introduced inadvertently with tropical plants or soil from Southeast Asia or Indonesia. When the flatworm specialist comes back from vacation, hopefully these photographs along with the dead specimen pickled in 70% alcohol in a vial on my mantel, will provide enough information to positively verify it's taxonomy and origin.

Terrestrial flatworms are predatory animals, in the group Platyhelminthes, a phylum more well-known for its many parasitic members. Of course, painting the terrestrial flatworm with the same broad brush applied to the liver fluke or tapeworm is about as fair as condemning all vertebrates for their relation to the kandiru, the tiny catfish whose existence makes urinating while swimming in the Amazon ill advised. That said, it can't be described as a beautiful creature, unless one has an uncommonly agreeable attitude toward natural beauty. Flattened and flaccid, yet muscular and sluglike, secreting a thick sticky mucus, and, when disturbed, forever waving its mushy little hammerhead around, it's certainly distinctive. Unlike its more famous relatives that spend most of their lives inside the bodies of other animals, this creature and its ilk feed on earthworms, tackling prey many times their own size. A terrestrial flatworm introduced to Ireland from New Zealand (an island group usually on the short end of the "alien invasive" stick) is eating through the annelid fauna of the Emerald Isle at an alarming rate. The ecological damage to Ireland, its soil, its crops, and its natural landscape has yet to be fully calculated, but the situation is worrying. Whether this flatworm in Boston is a cause for distress or not, is something I hope to determine.

More pictures--EDIT! plus some scientific validationCollapse )


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