The smallest known free-living organism is Pelagibacter ubique, which is one of the most common microorganisms found in the ocean. The mass of P. ubique in the world's oceans exceeds the mass of all fish in the oceans.
Pelagibacter ubique is one of the smallest known free-living bacteria, with a length of 370 to 890 nm (0.00037 to 0.00089 mm) and an average cell diameter of 120 to 200 nm (0.00012 to 0.00020 mm). They also have the smallest free-living bacterium genome: 1.3 Mbp, 1354 protein genes, 35 RNA genes.
The smallest organism in the world is found to be the Nanobes. They are simply filament-like structures. They can be obtained from rocks and sediments. They are smaller than that of the smallest bacteria mycoplasma that causes pneumonia-like disease.
Mycoplasma are the smallest living cells known and can survive without oxygen (facultative anaerobes). They completely lack a cell wall. Many mycoplasma are pathogenic in animals and plants. Example: Mycoplasma pneumoniae.
Some viruses are even smaller than Mycoplasma, e.g. poliovirus.
Note: The virus is smaller in size than mycoplasma but the virus is not considered as a cell because it does not have its cellular component. In presence of host-virus is living organisms and in absence of a host, viruses are a non-living organism.
The polio virus is the smallest known virus. It contains RNA in the spherical capsid. Poliovirus attacks the nervous system.
AAV is the smallest DNA virus with an average size of 20 nm. AAV was discovered in 1965 as a defective contaminating virus in an adenovirus stock (Atchison et al., 1965).
But if we look for the simplest creatures on the planet, we will find a wee bacterium that lives happily in the digestive tracts of cows and goats: Mycoplasma mycoides.
Notable extinct animal species include non-avian dinosaurs, saber-toothed cats, dodos, mammoths, ground sloths, thylacines, trilobites, and golden toads.
Bacteria are the smallest micro-organisms, ranging from between 0.0001 mm and 0.001 mm in size. Phytoplankton and protozoa range from about 0.001 mm to about 0.25 mm. The naked eye can see only the largest phytoplankton and protozoa. Most can only be seen under a microscope.
An organism that is not dependent on another organism for survival is known as a free-living organism.
The earliest life forms we know of were microscopic organisms (microbes) that left signals of their presence in rocks about 3.7 billion years old. The signals consisted of a type of carbon molecule that is produced by living things.
The smallest entity universally recognised to be a living organism (not everyone considers the slightly smaller nanobes to be alive) is Nanoarchaeum equitans.
Marburg virus disease. Marburg hemorrhagic fever is a severe and highly fatal disease caused by a virus from the same family as the one that causes Ebola hemorrhagic fever. Both diseases are rare, but can cause dramatic outbreaks with high fatality. There is currently no specific treatment or vaccine.
Discovery of the Giant Mimivirus. Mimivirus is the largest and most complex virus known. Is it an evolutionary bridge between nonliving viruses and living organisms, or is it just an anomaly? Viruses are small and fairly simple.
Is polio eradicated? Wild poliovirus types 2 and 3 are globally eradicated. That means there aren't any naturally occurring cases anymore. Poliovirus type 1 has been eliminated in most countries but not eradicated worldwide.
The disease is now rare in the U.S. because of a vaccine against the virus. However, polio still exists in a few countries. People who have not been vaccinated can get it while traveling to a region where the disease still happens.
One of the things that makes polio eradicable is the fact that humans are the only reservoir. No poliovirus has been found to exist and spread among animals despite repeated attempts to document this.
Mycoplasma gallicepticum is the smallest cell. Mycoplasma's size is 0.2–0.3 μm. Mycoplasma are the smallest living organisms on the earth.
Answer: The sperm cell is the smallest cell in the human body. The volume of these cells is quite tiny. The head of a sperm cell is roughly 4 micrometres long, about the same size as a red blood cell (RBCs). Egg cells are the biggest cells in the human body (ovum).
Viruses are also the smallest germ, making them generally the easiest to contract—they're so tiny they can spread through the air in a cough or a sneeze.
World's Oldest Water Lies At The Bottom Of A Canadian Mine And Is 2 Billion Years Old.