Unfurling marvels, ribbon worms vary from a few inches long to nearly 200 feet (60 meters)—the longest animals on the planet. Voracious predators that hide under rocks in intertidal zones or in the open sea, many are equipped with neurotoxin-tipped barbs on their proboscises for impaling other worms, their main prey. One of the toxins found in ribbon worms, anabaseine, shows potential for the treatment of Alzheimer's disease. (This species, Baseodiscus delineatus, had not been seen before in Hawaii.)