Final answer:
Parasites can avoid being phagocytized due to the coating of exterior IgM antibodies, which resemble molecules produced by host cells. This prevents the immune system from recognizing and attacking the parasite.
Step-by-step explanation:
Parasites can avoid being phagocytized due to various mechanisms. One of these mechanisms is the coating of exterior IgM antibodies. These antibodies act as a protective cloak that prevents the immune system from recognizing and attacking the parasite. By resembling molecules produced by host cells, the IgM antibodies allow the parasite to escape detection by the immune system.