Find out how to avoid getting the flu this winter. There are plenty of good websites containing wonderful pictures of those very tiny organisms. Your message could be here. Sponsorship opportunities available now.
Microbiologists study all critters small and tiny.
These critters include viruses, bacteria, fungi, and parasites. Viruses are the smallest things we study. They are very wimpy . They all require another living cell to reproduce. I would call them the ultimate parasite.