Bipalium adventitium is a predatory terrestrial planarian. Klots (1960) reported that B. adventitium preyed on "small annelids" as well as on slugs and insect larvae. He did not, however, give details or specify what species of slugs the planarians had eaten. According to recent studies, B. adventitium preys exclusively on earthworms. For example, Ducey & Noce (1998) reported that their specimens did not eat 2 species of slugs (Arion sp. and Deroceras sp.) that were offered to them.
I have had one captive B. adventitium since the end of September. I have fed it 2 earthworms and I have also been testing to see if it will eat the native northeast American slug, Megapallifera mutabilis. In the first test I did 2 weeks ago, 2 slugs survived about 20 h in the same container with the planarian. On several occasions, I observed the planarian contacting the slugs and also crawling on them, but it never, as far as I could tell, attempted to attack them by everting its pharynx (yes, that's what they do).
Touch but don't eat: Bipalium adventitium making contact with a Megapallifera mutabilis.
Tonight's test started 3 hours ago. The planarian hasn't eaten in 20 days. As of 10 minutes ago, the slug was still alive.
The experiment continues in Part 4.
Ducey, P.K. & Noce, S. 1998. Successful invasion of New York state by the terrestrial flatworm, Bipalium adventitium. Northeastern Naturalist 5:199-206.
Klots, A.B. 1960. A terrestrial flatworm well established outdoors in the northeastern United States. Systematic Zoology 9:33-34.