Terrestrial Ribbon worm with jumping spider prey (Nemertea sp). Like most of their marine relatives, terrestrial ribbon worms are thought to be predators, although the feeding ecology of most species remains unknown. Ribbon worms are notable for their proboscis, which is the primary organ used in capturing prey. This proboscis is a long hollow tube that is usually tucked away within a sheath that may stretch for nearly the entire body length. Singapore