## Friday, October 24, 2008

### What % of Biomass Do Unknown Species Represent?

David Pogue interviews E.O. Wilson about the Encyclopedia of Life project, and asks him how many species are known and unknown:

And in that period of time, we have found and given names to perhaps one-tenth of what's on the surface of the earth. We have now found 1.8 million species. But the actual number is almost certainly in excess of 10 million, and could be as high as a hundred million, when you throw in bacteria.
Looks like we have found around 10% of all species. Although, how exactly can you know until we find them all? Geneticists believed humans had around 100,000 genes until they sequenced the genome and found out we only have 20-25,000.

Assuming we only are aware of around 10% of all species, I am curious as to what percentage of total biomass they represent? I would think that the reason the other 90% are still unknown is that they aren't particularly prevalent.

As I wrote about in how long the long tail, you can estimate this by using a Pareto power law distribution and selecting an exponent that best fits the data. While I don't know what that exponent would be, I would guess it would be similar to the net worth of Americans which has an exponent of 1.1. If this were the case, then the top 10% of species would account for 81% (.1^(1-1/1.1)) of total biomass. The 90% of unknown species would account for only 19% of all biomass.

With good data on the biomass of species, the exponent could be determined. But, when you start Googling on biomass, you realize that estimates of how much total biomass there is on Earth, and how much specific species account for are all over the place. This Google Answers has a nice collection of estimates. One source puts 90% of biomass as plants, another puts microbes at over 50% of biomass, while another places microbes and other biomass in hydrothermal vents as comprising more than 50% of total biomass (and these weren't even discovered until 1977!). It isn't clear which species ranks #1 in terms of biomass, although Wikipedia gives the title to krill at 500 million tonnes. Humans are estimated to have 100 million tons of biomass, while our domesticated animals make up 700 million tons of biomass. Certainly lots for room for further research on this topic, and more is needed to estimate the exponent.

And I completely agree with E.O. that we ought to be spending a lot more money exploring our planet and less on exploring other planets.
Listen: What would thrill people the most about space exploration? Surely it would be the discovery of life on another planet.

Then, Congress, if it weren't busted, would be willing to put out billions to explore that planet--find out all of the life forms there. Why shouldn't we be doing the same for planet earth? It's a little-known planet. Ninety percent of the life forms unknown to us.

And this is gonna be fun. This is a return to exploring a little-known planet.
I would love for a President Obama to make finding all species on Earth his "mission to the moon" and set a goal to accomplish this in 10 years. Similar to the quest to sequence the human genome, the US would take the lead position, but wouldn't do it alone. Instead we would encourage other countries to join with us and dedicate as many scientists as they can to the quest. I wonder how much money and how many scientists it would take to accomplish this in 10 years?