The Gulp Worm is a common earthworm infected with the t-virus. It hunts through the use of its highly sensitive exterior, by feeling vibrations emitted through sound and during movement. If it senses prey, the Gulp Worm will launch its considerable mass towards its target, generally knocking it to the ground, or consuming it whole.
The Gulp Worm is very similar to the Gravedigger, although it does not possess the latter's large mandibles.
This worm is actually in the prototype stage, and was used as a practice opponent for Rockfort Island's Anti-B.O.W. Squad trainees.
In Resident Evil Code: Veronica, the Gulp Worm never actually has to be fought. Claire can run past it in the Training Facility courtyard, as killing the Gulp Worm doesn't have any special reward; Chris can choose to run straight for the elevator and skip the Gulp Worm battle, but killing the Gulp Worm as Chris will get you the lighter, which in turn lets you get the Sub-machine guns.