The Planetary Society of Japan : Column

This is the website of "The Planetary Society of Japan"

YM COLUMN ARCHIVE

January 21, 2009

On tube worm

It was the year 1977 when the large community of living organism was found at the deep ocean bottom offshore the Galapagos Islands. Midget submarine crew must have been thunderstruck to have found such strange living beings. Back in those days, no one in the world believed there would have been such organism living at the depth of 2,600 meters under the ocean.

At the oceanic depths where magma is vigorously active, contact of the seawater with hot basalt blows out high temperature water of 350 degrees, too hot to call it hot spring.Why it’s called “water” at such high temperature is because it’s immensely high-pressured around the ocean bed. Water can’t be vaporized because of tremendous boiling point elevation. The pillars of hot suspending current mixed with various minerals would exactly look like intense black monsters. It’s quite understandable for it’s being called “black smoke”.

At the time of my childhood, creatures on earth were believed to have been given births at shallow beach. Its reason is because if animals can live by starch produced from plant’s photosynthesis of carbon dioxide with water, then it will be absolutely impossible for living beings could survive at the ocean depths of no photosynthesis without light. It was far beyond imagination that organic beings were happily enjoying their lives in community at such deep sea. Among all, most noteworthy is a tube looking like creature called “tube worm”. Below are their photographs in the websites:

http://dgukenvis.nic.in/image-galaryfo.htm

http://www.newscientist.com/data/images/ns/cms/dn10653/dn10653-3_600.jpg

Tube worms force themselves into the tube of their own make with their pink heads sticking out of it. Nowadays, they are found in Suruga Bay with the sizes from several tens of centimeters to larger ones of even two meters, and what’s strange about them is that they have neither stomach and intestines nor anus, which is to say they don’t have digestive organs. In the above websites, they look like flowers field with even eerie beauty.

Their organ structure is that they have gills at the head with muscle to control gill movement and they have nutritious body at the tail end where bacteria called “sulfur oxide bacteria” is parasitic in there. Tube worms live symbiotically with bacteria so as to survive on eating organic matters produced by bacteria in its body, which explains why they don’t need digestive organs.

“Sulfur oxide bacteria” can be said as the lowest unicellular plant but the question is how it can produce organic matters in the deep ocean without light. Its answer seems to be found in the explanation that they make organic matters by using energy that is produced from chemical reaction when hydrogen sulfide gushing out of seabed reacts with oxygen in seawater. In fact, tube worms suck into their organs, through eerie pink gill, hydrogen sulfide, oxygen and carbon dioxide that bacteria need; in return bacteria generate energy by chemical synthesis through reaction of the above elements to produce organic matters tube worms need.

It is believed that mysterious, astounding and yet attractive living beings represented by tube worm as a main player are still continuing to grow at the deep bottom as fast as shallow water creatures, which tell us there still exist the wonder worlds beyond our imagination on the earth. For those creatures not blessed from the sun, it is not “Mother Sun” but “Mother Earth” or “Mother Magma”. The very fact that this kind of lives exist on earth direct our mind toward Europa or Ganymedes, Jovian satellites, and Titan or Enceladus, the satellites of Saturn, looking for the lives on the other planets.

I welcome your opinions on this column to the following E-mail address.
matogawa@planetary.or.jp

(Translated by The Planetary Society of Japan)