Hydrothermal vents. Credit: NOAA

Does Life on the Seafloor Predict Life on Other Worlds?

Article Updated: 24 Dec , 2015

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Scientists have recently discovered communities of previously unknown species living on the seafloor near Antarctica clustered around hydrothermal vents. This discovery is certainly exciting for biologists, but it’s also important for astrobiologists. It begs the question — if life can thrive in the deep, dark oceans without sunlight, could similar life thrive elsewhere in our solar system or the universe?

For decades, scientists assumed the deep oceans were barren; sunlight can’t reach the ocean floor, making it an impossible environment for life as we know it to arise. But in 1977, oceanographers from the Scripps Institute discovered hydrothermal vents.

A schematic diagram of deep sea vent chemistry. Image credit: National Oceanic and Atmospheric Administration

These fissures, found along mid-ocean ridges on the seafloor of the Pacific, Atlantic, and Indian Oceans, create a natural, deep-sea plumbing system. Heat and minerals from the Earth’s interior vents out, providing a complex ecosystem that can reach up to 382 degrees Celsius (almost 720 degrees Fahrenheit). These ecosystems can support unique life forms that get their energy not from the Sun but from breaking down chemicals issued from the vents such as hydrogen sulphide.

The latest life forms, discovered in the Antarctic region by teams from the University of Oxford, University of Southampton and British Antarctic Survey, include a new species of yeti crab, starfish, barnacles, sea anemones, and potentially an octopus.

“These findings are yet more evidence of the precious diversity to be found throughout the world’s oceans,” said Professor Rogers of Oxford University’s Department of Zoology. “Everywhere we look, whether it is in the sunlit coral reefs of tropical waters or these Antarctic vents shrouded in eternal darkness, we find unique ecosystems that we need to understand and protect.”

Jupiter's moon Europa. The lines on the surface are breaks in the ice that lie on top of vast oceans. Image credit: NASA/courtesy of nasaimages.org

But it isn’t only biologists studying life on Earth that can benefit from this latest discovery. These peculiar environments on and beneath the seafloor could be a model for the origin of life on Earth and on other planets.

One particular target is Jupiter’s moon Europa. Recent research has confirmed that the moon has vast oceans buried beneath its frozen surface ice; it’s estimated to hold twice as much water as Earth. As such, it is a target for NASA in the search for life. It could be the case that some type of hydrothermal vent system exists on Europa, making its distance from the Sun irrelevant for life.

But just because sulfur or methane-based life on Earth can thrive around deep-ocean vents doesn’t mean the same is true on Europa. The presence of hydrothermal vents depends on geologic activity and a hot interior, neither of which has been confirmed. The possibility remains that light energy from the Sun could travel the distance to the moon and provide shallower portions of the subsurface oceans with life-giving light.

In any case, as scientists discover life in the more extreme environments on Earth, analogies are drawn with other worlds. If life is discovered in hostile parts of our planet, the same could theoretically arise in similar environments on other worlds.

Source: ‘Lost World’ discovered around Antarctic vents.

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interI0per
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interI0per
January 10, 2012 4:58 PM

well it certainly magnifies the possibilities.

Peter
Member
Peter
January 10, 2012 5:45 PM
Unfortunately, every Antarctic “new” life form is simply an adaptation from an existing and already varied branch of sea life. The blood worms at least, were more like a complete new species. This indicates that life, begun in ease can manifest itself in areas not as conducive to thriving. It does not indicate that there might have been an alternate basis for life or that species may have grown separate to our known biological tree. IMHO, this does practically nothing for astrobiological likelihood. I am sure that in a giant underground (er…underice) ocean, that there are bound to be thermal anomalies similar to Earth’s. Undoubtedly, where there is heat, there are heat extremes. What I’m saying is that… Read more »
Ales Marvan
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Ales Marvan
January 11, 2012 4:52 AM
But you are making a assumption, based on limited facts. At the end of the day these environments are few and far between, life in them is at a disadvantage as more energy rich locations are plentiful on planet earth. Life that would fully rely on them would simply not be able to compete today unless it was in complete isolation and devolved from the life that we see now. But earth wasn’t always a sunny, temperate, oxygen rich paradise, some 3.5 billion years ago the tables were turned, oxygen sucking photosynthetic life would have been at a disadvantage. Its unfortunate that our understanding is so limited from those periods of time, we really dont know much. In… Read more »
Torbjorn Larsson OM
Member
Torbjorn Larsson OM
January 11, 2012 2:44 PM
As you can see from my own reply to Peristroika I have to agree with you too. But I have a few nitpicks on the biology: – The process is “evolution”, and it is a stochastic & deterministic causal process that can only proceed forward as adaptation or drift fixes genes. (I.e. see to it that certain alleles of a gene is in a stable proportion in a population.) Biologists never say “devolve” because it doesn’t make sense for this process of fixation. Species can both gain (say, predators) and loose (say, parasites) traits. But they have to do so from what they start out with. Most of the time you find that alleles can’t be loosed to… Read more »
Torbjorn Larsson OM
Member
Torbjorn Larsson OM
January 11, 2012 2:18 PM

I agree with the general sense here, this is more telling on adaptation of biological evolution. Early life was likely less robust because it wasn’t as diversified or individually capable. We know that the DNA UCA was about as complex as today’s prokaryotes from gene family estimates, but the RNA world couldn’t be as RNA had to be in the form of populations of many small strings instead of a prokaryote’s few DNA strings.

But generally these finds of modern complex communities or animals points to possibilities, see my ref to oxygen-free animals above. This is how biologists have been using them in a long tradition going back to Darwin and his peers.

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
January 10, 2012 6:07 PM
It certainly seems enough. When a differentiated body cools down, metabolic network chemical evolution is at its fastest. Hydrothermal vents would provide longer lasting refuges and more energetic redox energy sources for these networks as the body cools further. In addition, the separation between reducing and oxidizing environments as well as the thermal cycling provides a more differentiated chemistry. As well as an initial compartmentalization into chemical cells that drives smaller compartments down to the size of vent pores. A pore opening is enough to set up an electrochemical potential difference akin to what closed cells utilize, which is telling on how naturally these environments tend towards cellular systems. Alkaline systems (on Earth supplemented by plate tectonics subduction… Read more »
Lawrence B. Crowell
Member
Lawrence B. Crowell
January 10, 2012 8:03 PM

The question is whether this can exist on Enceladus. Europa might be a better bet, but I doubt we are going to drill through the ice mantle at all soon. A fly through of the geyser jets flying off of Enceladus seems more technically feasible.

LC

William928
Member
William928
January 11, 2012 1:20 AM

Another question is whether the proper chemical process could take place in the Methane lakes on Titan. It’s encouraging that we’re asking these questions, IMHO.

Kawarthajon
Member
Kawarthajon
January 10, 2012 7:36 PM

There are also cold seeps on Earth, which have low temperatures (though I couldn’t find exactly how low, but I’m guessing no lower than 2C), which could be a possibility for life on other worlds. I’m not sure if hydrocarbons could seep out on other worlds, like they do here.

So, when’s that probe going to Europa?

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
January 11, 2012 2:07 PM

Good to know! Certainly low temperatures promote nucleotide formation, to the degree that Miller and others have suggested ice-thaw cycles as the formative environment instead.* Cold seep circulation could be a variant, and come to think of it methane clathrates formed at high pressures a potential alternative to water ice for that matter.

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* I think the high temperature processes that kicks in earlier and is generally more productive will have the advantage in general.

Then again, the universes is large so these things will likely happen once on a blue ice moon too.

Tanya Denis
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Tanya Denis
January 11, 2012 1:19 AM

Can’t we all just get along.

Anonymous
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Anonymous
January 11, 2012 5:36 AM

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EdR
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EdR
January 11, 2012 2:35 PM

Is anyone aware of research on the DNA ancestry of these life forms? It might be possible to determine if they evolved from related organisms from the surface or the other way around–or if any of them went on a separate path.

Cherri Dawson
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Cherri Dawson
January 11, 2012 5:08 PM

I would have to say yes it does. Just because we need o2 to breath does not mean other planet creatures would need it to grow .

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