In the class of things not to do while eating, take a look at this clip from the BBC's forthcoming documentary series Wonders of the Monsoon, showing a leech that was obviously never told not to eat anything larger than its head, or whole body for that matter.
The footage was shot on Mount Kinabalu, Borneo, and will make you very glad you are not a worm. It may also make you quite glad that something that size has abandoned sucking the blood of humans.
A species of giant red leech, currently known as Mimobdella buettikoferi, was identified in the area in the late 19th century, although it is now thought to possibly have been placed in the wrong genus. It is unclear whether the leech the BBC filmed is the same one or something that looks similar.
On the other hand, those who work in the field have a much more positive response. Leech expert Dr. Mark Siddall of the American Museum of Natural History said, “I think the BBC footage is terrific and I am eagerly looking forward to the Monsoon series. I have often wanted to see this in action for myself; the only existing video (from a related species in Japan) suggests they eat earthworms sideways, which never made sense to me. Williams and his team have made an important contribution to my field. It will be interesting to see if this is indeed a new species, or if we leech taxonomists got it wrong in the past. The leech is part of a numerous and globally distributed group (Erpobdelliformes), none of which feed on blood. Some live right here in Central Park, though their size is more typical of other leeches, so they feed on insect larvae, not on giant earthworms."