You’ll want to make sure that you’re big enough to eat a tail segment, so eat some of the food creatures first. Once that’s done, you can distract the weird snakey thing by hanging out by food, then going after the last tail segment. Once you bite that off, it’ll withdraw into itself for a bit before coming after you full force. Be ready to run, and try to wait it out until it’s distracted again. After that, it’s a matter of repeating the process. Distract, eat tail, run.