Top 10 Smallest Living Creatures on Earth

Creatures those are not even visible to naked human eye exists all around us. From small Sea Urchins to Nanobes, they are all around us. From a unicellular organism to a multi cellular creature, they support our life form in some or other ways. The smallest creatures living on earth can be categorized by their size, height, volume, mass or length. The mysterious earth has millions of such living creatures ranging from only 0.0002 mm to as small as 0.0001 mm creatures. Knowing the size of these animals one would wonder how they even got discovered and who knows what is yet to be discovered. Let’s find out what lies with our mystic earth.

10 Sea Urchins



Sea Urchins are found in the oceans floors throughout the world except for the polar region. They are most commonly found in the rocky floors of the ocean in both deep and shallow water bodies. Sea Urchins are mainly spherical in shape and nearly 200 species has been recognized so far, of all the shapes and sizes.  Belonging to the family of Echinoidea, the smallest Sea Urchin is known as Echinocyamus Scaber that is merely 6 mm (Milimeter) in length. Sea Urchins feed on almost all kinds of plant and animal and hence are omnivorous. Sea Urchins feed on the algae and decomposing fish, mussels, barnacles etc. Red Sea Urchins is the longest living creature in the world with some having life expectancy of more than 200 years.

9 Starfish


Courtesy: Animals World

Also known as Sea Stars, Starfish belong to the class of Asteroidea. They are found in the depth of around 6,000 meters in the oceans throughout the world. Starfish looks like a star with five arms arising out of a central disc. Some starfish have more than five arms which could be seen in variants of bright colors. Starfish could reproduce both sexually and asexually based on their origin. There are approximately 1,500 species of starfish found all over the world, the smallest of which is Parvulastra Parvivipara. This specie of starfish is only 5 mm in size, and is found in the South Australian coasts.

8 Sea Cucumbers



Yet another smallest creature on earth is a Sea Cucumber which is again an aquatic animal. Belonging to the class of Holothuroidea, Sea Cucumbers are Echinoderms. They have long cylindrical body similar to a cucumber, having a branched reproductive organ at one end. They are found in the sea beds throughout the world whereas maximum number of species could be found in Asia Pacific territory. There are by far 1,717 species of Sea Cucumbers known to the world. The smallest Sea Cucumber is Psammothuria Ganapatii which is only 4 mm in length. Psammothuria Ganapatii is found in the sea coasts of India on the sand grains.

7 Beetles


Courtesy: Animals Adda

Beetles are the form of insects found in all parts of the world except for marine habitats and Polar Regions. They belong to the class of Coleoptera and have more than 300,000 species form on earth. Beetles are adaptive to almost all forms environment. Beetles are necessary evil for the environment as some forms destroy the crops and agricultural products whereas some species help in decomposition of dead and decaying. Beetles from the family of Nanosellini are the smallest beetles which are less than 1 mm long. Scydosella Musawasensis, the smallest of all the beetles is only 300 μm in length.

6 Eriophyidae


Courtesy: Wikipedia

Also known as Gall Mites, Eriophyidae are Plant Parasites. Eriophyidae feed on plants by causing damage to the plants tissue and forming galls. There are more than 3,600 forms of Eriophyidae found all over the world. Eriophyidae are invisible to naked eye and hence can be seen only through microscopes. The microscopic mites look like the worms having only two pairs of legs. They are usually yellow-pinkish and white-purplish in color and measure only 125 to 250 μm in length.

5 Crustaceans



Belonging to the Phylum Arthropods, Crustaceans are living animals. They could be either parasitic or terrestrial or could be aquatic. The most commonly known Crustaceans are lobsters, crabs, shrimps, crayfish etc. There are more than 67,000 species of Crustaceans of sizes ranging from 3.8 meter to 0.1 millimeter. The smallest Crustaceans is Stygotantulus Stocki which is only 94 µm in length and belongs to the class of Tantulocarida.

4 Eukaryotes



Any organism having a clearly defined nucleus enclosed within a membrane is Eukaryotes. The Eukaryotes belong to the group of Eukarya or Eukaryota. Eukaryote is very wide term as all the multicellular organisms are Eukaryotes. The unicellular organisms involve various forms of Algae and Protozoa. The smallest member of Eukaryotes family is Prasinophyte Algae measuring only 0.8 μm.

3 Nanoarchaeum



Nanoarchaeum is a spherical shaped organism and is only 400 Nanometer in diameter. Also known as Archaeal Parasite, Nanoarchaeum was first discovered in the year 2002 in Iceland a hydrothermal vent. It belongs to the species Nanoarchaeum Equintas which means “Riding the fire Sphere”. In order to grow and reproduce the Nanoarchaeum requires some specific conditions. The ideal temperature for its growth is 90 degree Celsius and prefers the place rich in Sulfur, Hydrogen and Carbon Dioxide. It cannot reproduce on its own as it lack flagella and can only grow on an Archaeal host known as Ignicoccus Hospitalis.

2 Mycoplasma Genitalium

Mycoplasma Genitalium


A parasitic bacterium by nature, Mycoplasma Genitalium is found in respiratory organs of human body. Mycoplasma Genitalium causes genital diseases and could be transmitted through unprotected sexual intercourse. However, disease caused by Mycoplasma Genitalium could be treated with the help of antibiotics. It is an ultramicrobacterium as it is much smaller than other bacteria with its size ranging from 200 to 300 Nanometre.

1 Nanobes



Nanobes are said to be one tenth of the size of smallest bacteria and are supposedly smallest living creature in the world. However, their classification, whether they are living or non-living, has been under debate for long. But due to technological advancements, it has been stated by some scientists Nanobes can reproduce and also posses DNA. Nanobes are found on some rocks and sediments and looks like a tiny filament. Nanobes are only 20 nanometer in diameter, due to which it is merely impossible for them to reproduce as they are too small to have the basic components to reproduce. So, if they reproduce there have to be some unusual way through which they reproduce. The fact that whether Nanobes are a single living creature or a part of some larger living creature is still controversial.

About the author


Leave a Comment