acanthocephalan: any of various worms living parasitically in intestines of vertebrates having a retractile proboscis covered with many hooked spines
worm: any of numerous relatively small elongated soft-bodied animals especially of the phyla Annelida and Chaetognatha and Nematoda and Nemertea and Platyhelminthes; also many insect larvae
fly: an opening in a garment that is closed by a zipper or by buttons concealed under a fold of cloth