Mail Buoy

January 20 responses:

How many years of training did you go through to do research like this?

Kate
Ms. Sheild's classes at Clarke Middle School, Lexington, Mass.

Dear Kate,

The science crew of the expedition includes undergraduate and graduate students, postdoctoral researchers, and early- and mid-career scientists. Undergraduate students can be sophomores or seniors, while the scientists are in general five to 10 years past their Ph.D. graduation.

Best,
Dionysis Foustoukos
Geochemist
Carnegie Institution of Washington

Hi Kate,

Getting to the stage where I am now is quite a long process that took something like 20 years. It requires hard work and a lot of dedication, but also some luck by being at the right place at the right time. I started studying biology back in my hometown, Mainz, Germany. Even though I was landlocked and only saw the ocean for the first time when I was 16, I was always fascinated by it. This is why I decided to move to the north of Germany, to Bremen, to study Biological Oceanography after having received my bachelor in biology. I did my Ph.D. work studying a shallow-water hydrothermal vent site in Milos, Greece, after which I was lucky to land a postdoctoral position at WHOI. Subsequently, I was offered a faculty position there. Being able to start my own research by studying deep-sea vents was a dream come true for me, especially after I had a chance to dive in Alvin. I was hooked for sure. I feel extremely privileged to be able to do the work I am doing, and I enjoy it immensely. My message to you and everyone would be to follow your dreams and to work hard to make them come true.

Stefan Sievert
Microbiologist and Chief Scientist
Woods Hole Oceanographic Institution

Dear Kate,

After my Masters of Engineering in Biosciences (five years), I spent seven months at the Auckland University of Technology in New Zealand, where I studied the ecology of mangroves. I then went back to France and worked for two years on defense mechanisms in algae. In 2008, I started my Ph.D. in marine microbiology at the Station Biologique de Roscoff (France), studying how bacteria eat sugars, and graduated in 2011. Since then, I've been a postdoctoral researcher at the Woods Hole Oceanographic Institution.

François Thomas
Postdoctoral Researcher
Woods Hole Oceanographic Institution

Hi Kate,

In my case, I'm now a first-year Ph.D. student. I've gone through more than seven years of training in science.

Xi Wei
Graduate Student
Helmholtz Centre for Environmental Research, Leipzig, Germany

Hi Kate,

I acquired my educational background mostly in Germany. I went to general schools up to graduation from the German equivalent of high school (13 years). This was followed by two years of studying chemistry at the university, which I basically wasted with extracurricular activities (adding to my life's experience). I found what I wanted in studying biology in Muenster, Germany, and received my Ph.D. after another nine years. From there, I was offered a postdoctoral fellowship in San Diego funded by the German government, which I enjoyed for three years. Ever since then, I have been a faculty member at the University of California San Diego, Scripps
Institution of Oceanography.

Best regards,
Horst Felbeck
Marine Biologist
Scripps Institution of Oceanography

How many organisms chemosynthesize?

Joey
Ms. Sheild's classes at Clarke Middle School, Lexington, Mass.

Hi Joey,

Great question. There are many possible ways to answer your question, because it's such a fundamental one, and very little is known about it. I'll try and let you know what we do know!

As an aside, chemosynthetic organisms have been known since the late 1800s, when a Russian microbiologist named Sergei Winogradsky described how some bacteria can get energy from nitrite, a chemical similar to nitrate found in fertilizers.

There are many different organisms that can chemosynthesize, but all of them are found in two major groups: bacteria and archaea. Bacteria are small, single-celled creatures you can't see without a microscope. Archaea are similar to bacteria; some archaea look exactly the same as bacteria under the microscope. We only know they are different because of their DNA sequences and their chemical composition.

Outside of bacteria and archaea, no other organisms to my knowledge can chemosynthesize. No plants, animals, or any other types of microorganisms can do this.

Within the bacteria and archaea, there are many that can chemosynthesize. I can't list all of them, but instead I can tell you a few different categories of organisms so you can understand how diverse they are. Just like we can categorize animals into herbivores, carnivores, and omnivores, we can also categorize chemosynthesizers into categories based on where they get their energy. When they get energy from something, we say they 'oxidize' it. Here are some examples:

• Sulfur oxidizers (very common at vents)
• Hydrogen oxidizers (also present at vents)
• Ammonium oxidizers (in the ocean, below where the algae live)
• Nitrite oxidizers
• Iron oxidizers
• Manganese oxidizers

...and the list goes on. As you can see, there are many types, and there are many species in each category. Some organisms can also oxidize more than one chemical at the same time.

In terms of total numbers compared to other bacteria or microorganisms, chemosynthesizers are not very abundant. Overall, photosynthesis is the main game on today's Earth, since there is so much energy available in sunlight. But in the past, and in places like vents nowadays, chemosynthesis is still the main game! This is probably a reflection of the ancient Earth, where this process was much more important before plants and animals evolved.

Most people like me who study chemosynthesis are interested in chemosynthesizers because they reflect this ancient Earth, billions of years in the past. Some people even speculate that chemosynthesizers could have been the original organisms that gave rise to life on Earth!

Hope that helps,

Jesse McNichol
Graduate Student
Woods Hole Oceanographic Institution

The structure of the earth is like the anatomy, so is it only the layers of the earth that make up the earth’s anatomy?

Brittany, Memorial High School, Eau Claire, Wis.

Hi Brittany,

Yes, Earth’s anatomy does consist of several layers of varying thickness and physical properties. There is what is thought to be a solid core at the center that is surrounded by an outer liquid core. The next layer out is the mantle, which behaves as a viscous liquid (think of molasses). The last and outermost layer is the solid crust that includes the continents and ocean basins.

In addition to these layers, there is more complex structure within some layers that is part of Earth’s anatomy. For example, because the outer crust consists of individual plates that move around on top of the liquid mantle, they collide and form what we call “subduction zones.” These are areas where one plate is forced to slide underneath another and is “subducted” back into the mantle. These areas may have many active volcanoes and experience frequent earthquakes.

If crust is being forced back down into the mantle, there must be new crust formed somewhere else to replace it; otherwise we would run out of crust. New crust is formed at what we call oceanic spreading centers. These are areas where volcanoes on the seafloor erupt and form new crust that very slowly moves away from the spreading center. During this cruise we are working at an oceanic spreading center known as the East Pacific Rise. The enormous amount of heat that is associated with molten rock that erupts and forms new crust is what drives the hydrothermal systems that we are studying. So, as you can see, there is a lot more to Earth’s anatomy than just its layers.

Jeff Seewald
Geochemist
Woods Hole Oceanographic Institution

For more information on Earth's Anatomy, see: www.divediscover.whoi.edu/anatomy