Final answer:
Amoebas, specifically Amoeba proteus, are typically about 500 micrometers in diameter, but some species, like Pelomyxa, can be significantly larger. Sizes vary within the Amoebozoa supergroup, which also includes pathogenic species. The largest known amoeba-infecting virus, Acanthamoeba polyphaga mimivirus, was so large that it was initially mistaken for a bacterium.
Step-by-step explanation:
The size of an amoeba can vary widely, depending on the species. One of the more familiar types, Amoeba proteus, is a large amoeba with an average diameter of about 500 micrometers (µm). However, it is dwarfed by the much larger Pelomyxa species, which can be over ten times its size. The giant acanthamoeba polyphaga mimivirus, which infects amoebas, can also be considerable in size, initially mistaken for a bacterium due to its large dimensions.
In comparison to other organisms, most prokaryotic cells range from 0.5 to 10 micrometers (µm) in size, and only a few giant prokaryotes might reach up to 500 micrometers (µm) in length. In the context of multicellular organisms, the individual cells may be around 10-100 micrometers (µm) in their maximum dimension.
It is important to note that amoebas are classified under the supergroup Amoebozoa, which exhibits a divergent range of sizes and includes pathogenic species to humans, such as Entamoeba histolytica and Naegleria fowleri.