ANSWER by Mark B.
Interesting biology question Amy. Flukes or TREMATODA are parasitic and are a type of flatworm. Based on what research I did, I could not find any references to their length. However, a relative of the flukes are the tapeworms or CESTODES. The most common species parasitic to man is TAENIA SAGINATA, the beef or ox tapeworm, so called because it grows inside cattle. Man can get the worm by eating raw or poorly cooked meat. Seldom fatal by itself, an animal will be weakened to a point were other diseases and sickness may develop. This species of tapeworm very often reaches a length of THIRTY FEET OR MORE! Now that's a long worm.
References, recommended reading:
Invertebrates, Insects, Volume 14 of the New Illustrated Animal Kingdom.
pg. 1684 "Tapeworms and Other Flatworms"
Grant Alternative School Library
Children' Britannica, Volume 13, Nitrogen to Philis.
Pg 218 Animal Parasites (this has a picture of fluke worms in a fish.)
Grant Alternative School Library% % page \* arabic % % page \* arabic