Category Archives: Bacteria

Born in the Badlands

If you’re even remotely interested in science, you probably heard the figurative bombshell dropped by NASA yesterday: They have found life on Earth that can build its genetic structure from arsenic. If you want the whole story, please read one of the journalistic articles; they will answer all your questions. But many friends have been asking me what my take on arsenic-based life is, and why it’s important. As it turns out, Element 33 and I share some history.

Here are the basics. There are six essential elements to life: Carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur. Phosphorus’ job in the life cycle is to make the backbone of the DNA double helix, and to act as a power source or battery as the “P” in “ATP,” which is the basic unit of currency for energy in all living things. It’s a pretty important job, you’d have to say. What astrobiologists working with a strain of Halomonadaceae protobacteria found in California’s Mono Lake discovered was that, if they starved the microbes of phosphate, while force-feeding them arsenic — which sits right below phosphorus on the periodic table, and shares many of its attributes — they could coerce the microbes into using arsenic in the place of phosphorus to build their DNA and energy base.

Halomonadaceae GFAJ-1, pictured above.

Disappointing, you say? Perhaps you were hoping for the discovery of poisonous Loch Ness Monsters oozing arsenic from their skin below Mono Lake? First, consider that phosphorus was once considered essential for all life. If you had a giant blender, and were to make five milkshakes out of a tree, a salamander, a mushroom, a bunch of E. coli, and a frozen mastodon penis, respectively, you’d find the same six elements in each shake. The fact that living things can replace one essential element with another means that they also probably do, which means that life is possible in far more places than we ever imagined. There could be life on a moon of Saturn that uses silicon instead of carbon, or selenium instead of sulfur. There could be a shadow ecosystem of microbes made of arsenic living unnoticed under our feet. And if so, and life evolved twice independently on Earth, it’s more than twice as likely that life has evolved on other planets, ending the supposed exceptionalism of our lonely space rock and suggesting that that we have interstellar neighbors.

This story is not about Mono Lake or arsenic, says Felisa Wolfe-Simon, the lead researcher, in the NY Times article, but about “cracking open the door and finding that what we think are fixed constants of life are not.” But for a second, let’s consider that insidious doppelganger of phosphorus, and that toxic lake in the foothills of the Sierra Nevada which is so important to so many life forms.

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Fans of the Hitchhiker’s Guide to the Galaxy will remember Slartibartfast, the planet architect who was very proud of his award-winning design for Norway. The fjords, he explained, were designed to give the continent a “baroque” feel. And a fjord is indeed a very splendid thing. A fjord, by definition, is a long and narrow inlet to the sea, flanked by very steep cliffs, and carved by glacial activity. (Or Slartibartfast.) While Norway coined the name “fjord,” they have no trademark on the geological flourish. You will find fjords anywhere there are mountains that meet the sea, and freezing temperatures to support glaciers, including the coast of Chile, New Zealand, and the Northwest coast of North America.

First Prize!

From time to time I like to take electronic expeditions to rare places on Earth, to see what I can find. Readers know I have a passion for fractals, and subscribe to something I call Fractal Earth Theory; the theory that the patterns of the planet are self-repeating ad infinitum. It was thinking about the true lengths of coastlines that led Mandelbrot to discover fractals in the first place; fjords make for rough edges in the world, wrinkling the land into a series of nooks and hidey-holes in which any manner of animal might live.

Today, we look for the unique wildlife of the fjords. I use a basic set of hypotheses as a compass:

1. Wherever life can exist, life will exist.
2. Where ever a habitat is geographically separated in any physical way, unique life will exist.
3. The more severely isolated a habitat is, the greater the number of unique species.

Fjords, however unique as geologic structures, are not very isolated: their cliffs connect with the mainland, and their inlets connect with the ocean. Their main aspects of geographic distinguishment are the steep angles of their cliffs, on which only certain wildflowers can grow, and the murky, silty, brackish water below. Fjords are often estuarine, with freshwater running as a river into their channels, which will certainly exclude many sensitive saltwater animals. The turbid, murky water is caused by violent tidal action, which in turn is caused by the water rushing over the lip of the terminal moraine left by the glacier at the fjord’s edge; this turbulence may also make the habitat even more exclusive, and more unique. But all in all, a fjord is not as isolated as a lake or an island, and we can’t expect a great number of unique species. But a few, sure. Some modifiers to the original compass:

4. The cold temperatures and low salinity will lead to a lower general biodiversity for animals, compared to a tropical habitat.
5. The cold water, with its high level of dissolved oxygen, will nonetheless support a high overall biomass.
6. The prediction of high aquatic biomass makes it more likely that any unique species are aquatic.

With these in mind, we set out to explore the nooks of the fjords, seeking life found nowhere else on Earth. And what we’ll find is a series of ecosystems among the most mysterious and little-known in science.

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The Crab at the Shore of the Known Universe

Meet today’s weird critter, the Yeti Crab!

It was only discovered in 2005, so scientists haven’t had time to study them properly yet. But they do know that those filaments on the arms house a bacteria which the crabs probably eat, and which might also filter out toxic chemicals from the water around the deep-sea vents where the crab lives.
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