Bipaliinae are found mostly in Madagascar, Southeast Asia and the Indian subcontinent (which includes countries such as Sri Lanka, Pakistan, Bhutan, Nepal, Bangladesh and the Maldives), Phillips said, though some species have established themselves in North America. They can grow more than a foot in length, often reproduce by dropping off part of their tail and regenerating, and eat earthworms, which makes them a threat to bait-farm operations, according to a 2009 article in U.S. News & World Report.
The worms’ mouths are not located on their oddly shaped heads. Instead, they’re right in the middle of their bodies, on their undersides, said Peter Ducey, a biologist at The State University of New York, Cortland, who researches these creatures. When the worms attack their prey, they first excrete glue-like mucus to adhere their soon-to-be dinner to their bodies. They then excrete digestive enzymes, reducing their prey to goo, which the flatworm can then suck up with its mouth (which also doubles as its anus). The non-squeamish can see pictures of this process at Ark In Space.