hydrothermal vents

Weird Clutch of Eggs Found in One of the Most Inhospitable Places on Earth

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Strange conditions in the murkiest depths of the ocean have led to the evolution of weird-looking animals that sometimes look like dicks but are, impressively, able to thrive in uniquely severe environments. One of the oddest and most inhospitable of these habitats is the area surrounding underwater volcanoes known as black smokers, which spew forth hot jets of chemicals from the Earth’s mantle that can reach temperatures of 650º-750º Fahrenheit. Scientists know that some hardy organisms rely on these chemical feasts to thrive, but they only recently realized that the searing heat from those vents might be crucial to their survival as well.

In a paper published Thursday in the journal Scientific Reports, an international team of scientists led by Pelayo Salinas-de-León, Ph.D. report an especially unusual discovery: that Pacific white skates (Bathyraja spinosissima), relatives of sharks that grow to have a wingspan of up to five feet, lay their eggs around hydrothermal vents in the Iguanas-Pinguinos vent field, about one mile below the sea just north of the Galápagos Islands.

pacific white skate deep sea hydrothermal vents
Pacific white skates can live up to 10,000 feet below the surface of the sea.

While the fossil record has shown that dinosaurs laid eggs in volcanic soil, just like the still-living megapode, a ground-dwelling bird that lays its eggs in mounds of heat-generating, decomposing matter in Asia and Australia, this report marks the first time anyone has observed this behavior in a marine animal.

Scientists found egg cases between 30 feet and 450 feet from hydrothermal vents.
Scientists found egg cases between three feet and 450 feet from hydrothermal vents.

Pacific white skates are wide, flat fish that can live up to 10,000 feet below the surface of the ocean. What makes this species especially unique is that their eggs take a really long time to hatch: Researchers estimate that these eggs incubate for 1,500 days — more than four years. Laying the eggs around these deep-sea vents, the researchers hypothesize, could help shorten the time it takes for the eggs to hatch.

This image, taken from the ROV's POV, shows skate eggs around a hydrothermal chimney.
This image, taken from the ROV’s POV, shows skate eggs around a hydrothermal chimney.

Since the hydrothermal vents of the Galápagos Marine Reserve are so deep underwater, the researchers had to use a remotely operated underwater vehicle (ROV) to explore what life could thrived there. Using the camera on the ROV, as well as a robotic arm that can gently manipulate objects, they observed the scene and collected four samples to confirm the species. In total, they found 157 egg cases, each about four inches long. Many of the cases were fresh, suggesting that the site was an active incubation area.

Deep-sea hydrothermal vents, known as black smokers, host a wide range of life, including skate eggs.
Deep-sea hydrothermal vents, known as black smokers, host a wide range of life, including skate eggs.

With the ROV’s camera, they also observed a bunch of older egg cases, indicating that skates had been laying their eggs around these vents for quite some time.

Even with the help of the hydrothermal vents, the water is still quite cold way down there — only a few degrees above freezing. So it makes sense that the skates are taking advantage of this environmental freebie.

Researchers collected four egg cases to confirm the species.
Researchers collected four egg cases to confirm the species.

Aside from being a startlingly strange find, documenting this phenomenon could assist conservation efforts in the future, as these deep-sea hydrothermal vents could soon be under threat. While it seems like something a mile under the ocean should be safe from human hinderance, they’ve recently become a target for mining companies hoping to extract methane or harvest the geothermal energy.

“We hardly know anything about the deep sea, and we are fishing, and mining, before we even get a chance to even document what species live down there and what unique behaviors [they] could reveal [to] us,” Salinas-de-León told National Geographic in an interview this month. Perhaps learning that these vents not only host the crabs and worms that we already knew about but also serve as nurseries for these strange and beautiful skates will teach us to be a little more hesitant to decimate these habitats for our own gain.

Abstract: The discovery of deep-sea hydrothermal vents in 1977 challenged our views of ecosystem functioning and yet, the research conducted at these extreme and logistically challenging environments still continues to reveal unique biological processes. Here, we report for the first time, a unique behavior where the deep-sea skate, Bathyraja spinosissima, appears to be actively using the elevated temperature of a hydrothermal vent environment to naturally “incubate” developing egg-cases. We hypothesize that this behavior is directly targeted to accelerate embryo development time given that deep-sea skates have some of the longest egg incubation times reported for the animal kingdom. Similar egg incubating behavior, where eggs are incubated in volcanically heated nesting grounds, have been recorded in Cretaceous sauropod dinosaurs and the rare avian megapode. To our knowledge, this is the first time incubating behavior using a volcanic source is recorded for the marine environment.

We need to rethink the origins of life on Earth, study suggests

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We might not have come from primordial soup after all.

For nearly nine decades, science’s favourite explanation for the origin of life has been the ‘primordial soup’. This is the idea that life began from a series of chemical reactions in a warm pond on Earth’s surface, triggered by an external energy source such as lightning strike or ultraviolet (UV) light.

But recent research adds weight to an alternative idea, that life arose deep in the ocean within warm, rocky structures called hydrothermal vents.

A study published last month in Nature Microbiology suggests the last common ancestor of all living cells fed on hydrogen gas in a hot iron-rich environment, much like that within the vents. Advocates of the conventional hypothesis have been sceptical that these findings should change our view of the origins of life.

But the hydrothermal vent hypothesis, which is often described as exotic and controversial, explains how living cells evolved the ability to obtain energy, in a way that just wouldn’t have been possible in a primordial soup.

Under the conventional hypothesis, life supposedly began when lightning or UV rays caused simple molecules to join together into more complex compounds. This culminated in the creation of information-storing molecules similar to our own DNA, housed within the protective bubbles of primitive cells.

Laboratory experiments confirm that trace amounts of molecular building blocks that make up proteins and information-storing molecules can indeed be created under these conditions. For many, the primordial soup has become the most plausible environment for the origin of first living cells.

But life isn’t just about replicating information stored within DNA. All living things have to reproduce in order to survive, but replicating the DNA, assembling new proteins and building cells from scratch require tremendous amounts of energy.

At the core of life are the mechanisms of obtaining energy from the environment, storing and continuously channelling it into cells’ key metabolic reactions.

Where this energy comes from and how it gets there can tell us a whole lot about the universal principles governing life’s evolution and origin. Recent studies increasingly suggest that the primordial soup was not the right kind of environment to drive the energetics of the first living cells.

It’s classic textbook knowledge that all life on Earth is powered by energy supplied by the sun and captured by plants, or extracted from simple compounds such as hydrogen or methane. Far less known is the fact that all life harnesses this energy in the same and quite peculiar way.

This process works a bit like a hydroelectric dam. Instead of directly powering their core metabolic reactions, cells use energy from food to pump protons (positively charged hydrogen atoms) into a reservoir behind a biological membrane. This creates what is known as a ‘concentration gradient’ with a higher concentration of protons on one side of the membrane than other.

The protons then flow back through molecular turbines embedded within the membrane, like water flowing through a dam. This generates high-energy compounds that are then used to power the rest of cell’s activities.

Life could have evolved to exploit any of the countless energy sources available on Earth, from heat or electrical discharges to naturally radioactive ores. Instead, all life forms are driven by proton concentration differences across cells’ membranes.

This suggests that the earliest living cells harvested energy in a similar way and that life itself arose in an environment in which proton gradients were the most accessible power source.

Vent hypothesis

Recent studies based on sets of genes that were likely to have been present within the first living cells trace the origin of life back to deep-sea hydrothermal vents. These are porous geological structures produced by chemical reactions between solid rock and water.

Alkaline fluids from the Earth’s crust flow up the vent towards the more acidic ocean water, creating natural proton concentration differences remarkably similar to those powering all living cells.

The studies suggest that in the earliest stages of life’s evolution, chemical reactions in primitive cells were likely driven by these non-biological proton gradients. Cells then later learned how to produce their own gradients and escaped the vents to colonise the rest of the ocean and eventually the planet.

While proponents of the primordial soup hypothesis argue that electrostatic discharges or the Sun’s ultraviolet radiation drove life’s first chemical reactions, modern life is not powered by any of these volatile energy sources. Instead, at the core of life’s energy production are ion gradients across biological membranes.

Nothing even remotely similar could have emerged within the warm ponds of primeval broth on Earth’s surface. In these environments, chemical compounds and charged particles tend to get evenly diluted instead of forming gradients or non-equilibrium states that are so central to life.

Deep-sea hydrothermal vents represent the only known environment that could have created complex organic molecules with the same kind of energy-harnessing machinery as modern cells. Seeking the origins of life in the primordial soup made sense when little was known about the universal principles of life’s energetics.

But as our knowledge expands, it is time to embrace alternative hypotheses that recognise the importance of the energy flux driving the first biochemical reactions. These theories seamlessly bridge the gap between the energetics of living cells and non-living molecules.

Origin of life: Chemistry of seabed’s hot vents could explain emergence of life

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Hot vents on the seabed could have spontaneously produced the organic molecules necessary for life, according to new research by UCL chemists. The study shows how the surfaces of mineral particles inside hydrothermal vents have similar chemical properties to enzymes, the biological molecules that govern chemical reactions in living organisms. This means that vents are able to create simple carbon-based molecules, such as methanol and formic acid, out of the dissolved CO2 in the water.

The discovery, published in the journal Chemical Communications, explains how some of the key building blocks for organic chemistry were already being formed in nature before life emerged — and may have played a role in the emergence of the first life forms. It also has potential practical applications, showing how products such as plastics and fuels could be synthesised from CO2 rather than oil.

“There is a lot of speculation that hydrothermal vents could be the location where life on Earth began,” says Nora de Leeuw, who heads the team. “There is a lot of CO2 dissolved in the water, which could provide the carbon that the chemistry of living organisms is based on, and there is plenty of energy, because the water is hot and turbulent. What our research proves is that these vents also have the chemical properties that encourage these molecules to recombine into molecules usually associated with living organisms.”

The team combined laboratory experiments with supercomputer simulations to investigate the conditions under which the mineral particles would catalyse the conversion of CO2 into organic molecules. The experiments replicated the conditions present in deep sea vents, where hot and slightly alkaline water rich in dissolved CO2 passes over the mineral greigite (Fe3S4), located on the inside surfaces of the vents. These experiments hinted at the chemical processes that were underway. The simulations, which were run on UCL’s Legion supercomputer and HECToR (the UK national supercomputing service), provided a molecule-by-molecule view of how the CO2 and greigite interacted, helping to make sense of what was being observed in the experiments. The computing power and programming expertise to accurately simulate the behaviour of individual molecules in this way has only become available in the past decade.

“We found that the surfaces and crystal structures inside these vents act as catalysts, encouraging chemical changes in the material that settles on them,” says Nathan Hollingsworth, a co-author of the study. “They behave much like enzymes do in living organisms, breaking down the bonds between carbon and oxygen atoms. This lets them combine with water to produce formic acid, acetic acid, methanol and pyruvic acid. Once you have simple carbon-based chemicals such as these, it opens the door to more complex carbon-based chemistry.”

Theories about the emergence of life suggest that increasingly complex carbon-based chemistry led to self-replicating molecules — and, eventually, the appearance of the first cellular life forms. This research shows how one of the first steps in this journey may have occurred. It is proof that simple organic molecules can be synthesised in nature without living organisms being present. It also confirms that hydrothermal vents are a plausible location for at least part of this process to have occurred.

The study could also have a practical applications, as it provides a method for creating carbon-based chemicals out of CO2, without the need for extreme heat or pressure. This could, in the long term, replace oil as the raw material for products such as plastics, fertilisers and fuels.

This study shows, albeit on a very small scale, that such products, which are currently produced from non-renewable raw materials, can be produced by more environmentally friendly means. If the process can be scaled up to commercially viable scales, it would not only save oil, but use up CO2 — a greenhouse gas — as a raw material.