Jurassic fossil shows thorny-headed worms once had mouths and guts
The Worm That Kept Its Mouth Every living thorny-headed worm is mouthless. The roughly 1,400 described species of Acanthocephala anchor to a host’s gut wall using a retractable, spine-studded proboscis and absorb nutrients directly through their outer body surface, no opening at the front end, no digestive tract behind it. That is the complete anatomy. … Read more