Introduction
According to common knowledge, the Sun is the source for all life on the planet. The sun fuels photosynthesis that produces the energy, in the form of sugars, which other living things consume throughout the various food chains.
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This cycle is illustrated below.
Background
The research that eventually led to the disproving this heliocentric theory of life began with the 1977 exploration of the Galapagos Rift by a team of scientists led by Jack Corliss from Oregon State University. 3 The Galapagos Rift is a part of the extensive network of volcanic rifts located throughout the world at the bottom of the oceans where the divergent tectonic plates meet.
Volcanic activity occurs as the tectonic plates move apart from each other . In many spots hydrothermal vents form where seawater, heated by magma, is released back into the ocean. This water ranges between 140°F to to over 750°F. 5
These hyrdothermal vents are commonly known as “Black Smokers” due to the dark coloration of the water as a result of high concentration of minerals. The formations are created by the minerals in the super-heated water accreting over time to form large chimney-like structures. 3
Exploring the ocean floor at a depth of 1.6 miles in a submersible named Alvin, the 1977 expedition was astounded to find that there was a thriving community of tubeworms, clams, crabs, and other extremophiles living in these incredibly harsh conditions.
Fascinated by the reports of biological diversity under such extreme conditions subsequent research missions began with the 1979 exploration led by scientists from Woods Hole Oceanographic Institution. As a result of this expedition the first scientific paper explaining the ecosystem was published by Dr. Peter Lonsdale in that same year. 3
Conditions at the vents9
- Tremendous pressure - 300 atmospheres
- Extreme temperatures - highest measured vent temperature is 757° F, highest temperature at which living tube worms have been observed is 212° F. Sea water is about 28° F at depths where vents form but can be up to 392° F near some vents.
- Chemicals - Hydrogen sulfide is toxic to most living things.
- pH - Vent fluid is very acidic with a pH as low as 2.8, which is very unhealthy for most living things.
Chemosynthetic Ecosystems
At the heart of the Black Smoker ecosystem is a simple family of thioautotrophic bacteria that convert minerals, in this case specifically sulfides, into organic matter in a process called chemosynthesis. 6 In the giant tube worms (Riftia pachyptila), seen in the previous video, the bacteria live inside of the tubeworm forming a complex symbiotic relationship at the cellular level.
The distinctive red plumes of the tubeworm contain hemoglobin that absorbs the toxic hydrogen sulfide from the surrounding water. The bacteria, which live in the tubeworm in a density of ~285 billion organism per ounce of tubeworm tissue, then breaks down the hydrogen sulfide into carbon compounds which in turn feeds the tubeworm. Tubeworms have no mouths or any type of digestive system whatsoever. Any nutrients must be absorbed directly into the body. The symbiotic relationship that has developed between this creature and the bacteria in its cells has solved this key issue. 8
Other inhabitants of the ecosystem such as shrimp and mollusks also eat the bacteria similar to herbivores eating plants on land. Those shrimps and mollusks are in turn consumed by other predators such as crabs in a natural cycle of predation. 8
It is also important to note that the inhabitants of these ecosystems are not only classified as extremophiles but also as thermophiles (thrives in heat) and psychrophiles (thrives in cold). In the case of the giant tubeworms the temperature difference may be as high as 150° F between one end of the creature closest to the vent water and the other end 3-4 feet in length away. The inhabitants of this ecosystem can withstand the highest temperatures of any multi-cellular organism on the planet as well as the highest concurrent temperature variation. 10
Chemosynthesis and Exobiology
For as many years as humans have resolved that all life is derived from the sun we have also taken a "Gaia-centric" view that all life must exist in conditions similar to life on the Earth's surface. "At 93 million miles from the Sun, Earth is pretty much in the perfect spot. As a result of its location and its significant greenhouse effect (CO2 and water vapor in the atmosphere), Earth maintains an average temperature of 59F - an ideal temperature for life to thrive." 11
Based on what can be observed miles below the surface of the ocean we know that this statement is incorrect. In fact life not only exists in the harsh conditions of the geothermal vents (thiotrophic symbionts) but also in large patches of semi-liquid methane (methanotrophic symbionts). Even the slow decay of whale carcasses over the course of many decades can produce forms of life that exists nowhere else other than in "whale falls". As seen in these examples the only requirement for life is the proper chemical response to a particular environment.
Indeed, the chemosynthetic processes described in this research paper may have been the calatyst for life on this planet. In 1952, University of Chicago researchers Stanley Miller and Harold Urey set up an experiment that approximated primordial Earth's thick atmoshphere of water, methane, ammonia, and hydrogen. After exposing the mixture to electrical charges simulating lightning a series of chemosynthetucs reactions that occurred which created organic compouns such as formaldehyde, cyanide, glycine, alanine and even ATP. A later re-analisys of the original solution archived for posterity shows that there were a total of 22 amino acids created during the experiment and not just the five that were published. The technology at the time of the experiment did not possess the requisite sophistication to detect them.
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