Question: How many organisms are in the world today?

Sean Clement answered on 13 Jun 2011:

Morning Beach!

Seriously good question, and a very difficult one to answer. How many organisms are alive in the world today? Well, there are nearly 7 billion of us for a start! Then, before you even get outside of our bodies, think of all the bacteria that live within us! Do we count them or do they count as a part of us? That’s a mind-bendingly big number before we even stop talking about people!

In honesty, I don’t think we’ll ever be able to say ‘There are this number of organisms alive today’ as we’re still finding life in places where we didn’t think anything could live, for instance, just recently, a team of scientists exploring the wreck of the Titanic found bacteria living on the hull. Amazing enough to find it in the depths of the ocean but then they found that it survives by eating the ship itself! Incredible!

If we look at the question a different way though, and ask how many species of of organism are alive today, the we get a slightly more manageable number. We know of roughly 1.7 million extant species (good word to use that, it means the opposite of extinct) alive today. By this, I mean these are species that we’ve given name to or described. There is a very long list of species waiting to be given names, possibly even as many as we’ve named already! As I said before, we’re still finding life everywhere so this number can only get bigger and bigger.

One last thing to leave you with: All of the species, known and unknown, alive today account for less that 1% of all the species of organism that have existed since the dawn of life on earth. Crazy…

Hope that answers your question!

Sean