The smallest known organisms in the world are actually a type of ultra-small bacteria known as mycoplasmas. Among them, Mycoplasma genitalium holds the title for the smallest free-living bacterium, measuring about 0.2 to 0.3 micrometers in diameter. This bacterium lacks a cell wall, which contributes to its tiny size and unique characteristics.
While people might refer to nanobes when discussing ultra-small organisms, there’s some debate around the classification of nanobes. Initially thought to be living organisms due to their size, many scientists believe that nanobes may actually be remnants of larger organisms or non-living structures. Size-wise, nanobes can be even smaller than mycoplasmas, typically around 0.1 micrometers or less.
In summary, while both ultra-small bacteria like mycoplasmas and nanobes exist, the smallest confirmed living organisms are mycoplasmas, not nanobes. The study of these diminutive life forms provides insights into the limits of life and the complexities of microbial diversity.