What Is Left to Explore?
What is left to explore? Why, the biosphere of course, that razor-thin membrane of life plastered to the surface of Earth so thin it can’t be seen edgewise from an orbiting space vehicle yet still the most complex entity by far we know in the universe. How well do we understand this part of the world? Proportionately not very much. We live on a little-known planet. Let me give you some examples.





The best-studied animals are the birds, which have been carefully collected by naturalists and explorers for centuries. Nevertheless, an average of 3 new species are added each year to the 10,000 already described by scientists. Comparable to them are the flowering plants: about 280,000 species known out of 320,000 or more estimated to exist. From there it goes steeply downhill. You’d think that the amphibians—that is, frogs, salamanders, and caecilians—would be comparable to the birds, but in fact they are still poorly explored: from 1985 to 2001, 1,530 new species were added to the 5,300 already found, an increase of over one-fourth, and with more new species pouring in.







When we next move to the invertebrates, what I like to call the little things that run the world, we get a fuller glimpse of the depth of our ignorance.







Consider nematode worms, the almost microscopic wriggling creatures that teem as free-living forms and parasites everywhere, on the land and in the sea. They are the most abundant animals on Earth. Four out of every five animals on Earth is a nematode worm. If you were to make all of the solid matter on the surface of Earth invisible except for the nematode worms, you still could see its outline in nematode worms. About 16,000 species are known to science; the number estimated actually to exist by specialists is over 1.5 million. Almost certainly the world’s ecosystems and our own lives depend on these little creatures, but we know absolutely nothing about the vast majority.







To continue: about 900,000 kinds of insects are known to science (I’ve just finished describing 340 new species of ants myself, for example) but the true global number could easily exceed 5 million.







How many kinds of plants, animals, and microorganisms make up the biosphere? Somewhere between 1.5 and 1.8 million species have been discovered and given a Latinized scientific name. How many species actually exist? It is an amazing fact that we do not know to the nearest order of magnitude how many exist. It could be as low as 10 million or as high as 100 million or more. Those of us in biodiversity studies say that we have knowledge of only about 10 percent of the kinds of organisms on Earth.







The nematodes and insects and invertebrates all shrink in diversity before the bacteria and archaea, the dark matter of planet Earth. Roughly 6,000 species of bacteria are known. That many can be found in the 10 billion bacterial cells in a single gram, a handful, of soil—virtually all still unknown to science. It’s been recently estimated that a ton of fertile soil supports 4 million species of bacteria. We believe each one is exquisitely adapted to a particular niche, as a result of long periods of evolution. We don’t know what those niches are. What we do know is that we depend on those organisms for our existence.







A search is on right now at least for the bacteria that live in the human mouth. The number of species adapted to that environment so far is 700. These bacteria are friendly; they appear to function as symbionts that keep disease-causing bacteria from invading. For those species your mouth is a continent. They dwell on the mountain ridges of a tooth; they travel long distances into the deep valleys of your gums; they wash back and forth in the ocean tides of your saliva. I’m not suggesting that we give an Explorer’s Club flag to a dentist. But you get the point.







Every part of the world, including Central Park where a new kind of centipede was recently found, has new kinds of life awaiting discovery.







But—if none of this impresses you, would you like an entire new living planet for your delectation? The closest we may ever come is the world of the SLIMES (that’s an acronym for Subterranean Lithoautotrophic Microbial Ecosystems), a vast array of bacteria and microscopic fungi teeming below Earth’s surface to depths of up to 2 miles or more, completely independent of life on the surface, living on energy from inorganic materials, possibly forming a greater mass than all of life on the surface. The SLIMES would likely go on existing if we were to burn everything on the surface to a crisp.







In approaching biodiversity, we are all explorers, scientists and all others who care about the natural world, now put in perspective, like Cortez and his men on a peak in Darien, before the new ocean, staring, in Keat’s expression, in wild surmise at the unknown world stretching before us.







E. O. Wilson's Explorers Club Speech



18th March 2006