A tapeworm has no alimentary canal because

Explanation

A tapeworm is a type of parasite that lives in the intestines of animals, including humans. The question is asking why a tapeworm does not have an alimentary canal. The alimentary canal is the tube-like structure that runs through the body and is responsible for processing food. The options provided are: it is antotropic, it does not feed, it has no enzymes, its body absorbs digested food, or it is long. The correct answer is option D, which states that the tapeworm's body absorbs digested food. Unlike other animals, a tapeworm does not have a mouth or a digestive system. Instead, it absorbs nutrients through its skin-like outer layer directly from the digestive system of the host animal. The host animal's digestive system breaks down the food into nutrients which are then absorbed by the tapeworm's body. This adaptation allows the tapeworm to survive in its host without having to expend energy on digestion. Rather, the tapeworm can focus all of its energy on reproduction and growth. While this may seem like an advantage for the tapeworm, it can be detrimental to the host animal's health, as the tapeworm can steal nutrients that the host animal needs to survive. In summary, a tapeworm does not have an alimentary canal because it absorbs nutrients directly from the host animal's digestive system, allowing it to focus all of its energy on reproduction and growth.