HOW MANY CREATURES ON PLANET EARTH?

We dominate Planet Earth.  Our world population is now more than 7.7 billion.  Where do we rank in numbers and mass?

The following bits of information were extracted from:  1  2  3  4  5 6 7 8

                                        Number               Million Tons

Bacteria                   10 to the 31th power    1,000,000 

                                ten nonillion

Land plants                                                      560,000

Marine plants                                                  5-10,000

Terrestrial animals                                                5000

Ants                         10 to the 18th power            3000

                                10 billion billion

                                1 quintillion

Marine fish                  ?                                800-2000

Cattle                       1.4 10 to 9th power               500

                                1.4 billion

Termites                                                                 445

Homo sapiens         7.7 billion                              385

Antarctic krill         500 trillion                             150

Sheep                      1.1 billion                                65

Domestic chickens 18.6 billion                              40

Great Whales              3 million                              20

(10 species)

Elephants                  0.5 million                               2

Some other interesting facts:

• All living creatures are eucaryotes (like us and plants), bacteria and archaea.
• At one time there were up to 5 billion passenger pigeons, which became extinct in 1914.  
• There are around ten quintillion insects (10 to the 19th power).
• Total number of animals?  20 billion billion, or 20 quintillion.
• Bacteria from 170,000-year old amber were activated.
• There are a million bacterial cells in a milliliter of fresh water.

These pie charts show how estimates of biodiversity have changed over time:

Ah, but then there are viruses, which brings up the question whether they are alive or not.  In any case:

• There are more viruses than everything else put together.
• But bacteria are 100 times larger than viruses.
• If there are ten times more viruses than bacteria, bacteria would be the dominant creatures on Planet Earth in terms of mass. However, if there are 500 times more viruses, they are #1.
• If you get sick with the flu, your body will be harboring 100 trillion viruses, or 10,000 times more viruses than people on Earth.
• Viruses kill 20-40% of all the ocean bacteria daily.
• The most often quoted figure is 10 to the power of 31 viruses on Planet Earth.  But there are more viruses than bacteria, so, maybe more.
• But if then, ten million more viruses than stars in the Universe.
• As tiny as they are, put end on end, viruses would stretch past neighboring galaxies, or a height of 200 million light years (the diameter of our Milky Way Galaxy is half that).
• In one gram of dental plaque are as many bacteria as the number of humans who have ever lived.  However, these studies are just beginning, but there are more viruses, and they primarily kill these bacteria.
• Viruses are responsible for cancer, polio, encephalitis, smallpox, the common cold, measles and AIDS.

How safe are you from microorganisms?  Scientist speculate that, swept up in air currents, tens of millions of bacteria and hundreds of millions of viruses settle down on each square meter of the surface every day.

Alive or not, viruses have been around for 300 million years.  For every bacterium, there are 500 viruses.  Some destroy bacteria, some attack humans.  Here is how they look.

A recent study indicated there there are as many bacteria (maybe weighing about half a pound total) that live in your body than you have cells.  More accurately, human cells only make up 43% of the body's total cell count.  However, these 38 trillion bacterial creatures are outnumbered in your body by 380 trillion viruses.  Click on this 2-minute clip to appreciate the relative size of these small creatures.  Here are two comparisons of sizes.

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