Endoparasites live in nutrient rich environment so most of their adaptations help them in maximizing absorption. In tape worm and round worm; there is an absorbent layer called tegument outside the body. This layer has villi-like structure which helps in better absorption of food. The endoparasites living in small intestine or large intestine get predigested food from their hosts so many of them may not have gut.
However, some of them have both gut and anus. 
Tapeworms also have suckers in mouth to absorb nutrients.

Endoparasites also show mechanisms to get transferred from one host to another. Sometimes, a part of their life cycle is spent in an intermediary host; such as in malarial parasite.