Question

Many of the simple worms are parasitic. Since they developed before other animals in the evolutionary sequence, discuss how they may have gone from free-living forms to their current parasitic ones.

Answer 1

Answer: The correct answer is : Parasitism arises several million years ago. The evidence shows that the parasites were initially free-living organisms that had contact with their host and managed to adapt to the same biochemical and biophysical environment. There are three theories about the origin of parasitism and they are:

inoculation of the agent through arthropod vectors

ingestion of the "pre-parasite" by its host

active invasion by the same parasites

You may think that there was a nutritional dependence