Tape worms are very long I believe, and bury their head in the wall of the intestine. We get them by ingesting the eggs in some food - more often in foreign countries with less hygienic food prep methods. I believe a tape worm can be longer than a foot...you'd have to Google it.
I think , in the Guiness Book of World Records, the longest tape worm recorded was almost 61 feet in length. I know, sounds crazy, but these can get so big and consume so much of the intake of a human, that person can actually suffer from malnutrition.
Yes, they can have. Tape worms are quite long in size. I have come across such a long sized worm in the stomach of a child. These worms usually affect the appetite of people in whom they are present. They eat but they still feel hungry.