Do Invertebrates Really Make Up 80% of All Species on Earth?

bug_girl has a new post called Planet of the Arthropods. She asks why we should care about invertebrates, "Why should we care about a bunch of squishy boneless animals? Because invertebrates make up EIGHTY PERCENT OF ALL THE SPECIES ON EARTH. They truly are the 'little things that run the world.'"

She links to this image ...


Isn't that amazing! Single-celled eukaryotes, fungi, and bacteria make up such a small percentage of total species (<1%) that they don't even register on this summary!

Here's a phylogeny of eukaryotes (no bacteria) from Keeling et al. (2005). If you look closely, you can find "animals" down in the lower right-hand corner. Isn't it amazing that one little insignificant branch represents 83% of all species on the planet? Seriously, something is wrong with taxonomy if this is even close to being true.


Estimates of the total number of bacterial species range from about one million to about one billion [Jonathan Eisen]. Read Carl Zimmer's New York Times article: How Many Species? A Study Says 8.7 Million, but It’s Tricky for an interesting perspective.

The general public has a very poor understanding of our relationship to all other species on this planet. We should be working hard to dispel the major misconceptions about biology and evolution.

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Keeling, P.J., Burger, G., Durnford, D.G., Lang, B.F., Lee, R.W., Pearlman, R.E., Roger, A.J., Gray, M.W. (2005) The tree of eukaryotes. Trends Ecol. Evol. 20:670-676. [doi:10.1016/j.tree.2005.09.005]