Mail Buoy
April 20, 2001
Hello my name is Michael Swift I’m from Morris Plains, New Jersey. My question is Why doesn’t the water turn black near the hydrothermal vents? Thanks for your time.
Mike Swift
Hello Mike:
The hydrothermal fluid that comes out of the vents does turn black -- check out the videos on the web site. When hydrothermal fluid mixes with the cold seawater, minerals precipitate out of the fluid making it appear black. Some of the minerals are trapped at the seafloor but some make it up into the water column and on this cruise, we have collected “black” water just above the vent site.
However, the water near hydrothermal vents does not in general turn black -- in fact, bottom water is quite clear. Think about this: imagine a big bath tub full of cold water and inject into it a thin stream of black water. The black water is quickly diluted away and the bath tub of water stays clear. The reason it does not go black is because the volume of black water is so small compared to the volume of water in the bath tub.
Hope this answers your question!
Keep Diving and Discovering!
Susan Humphris
Susan,
Thank you for all of your efforts on behalf of teachers and students of ocean science. Dive and Discover is a wonderful resource.
Discussions in class have lead to an interesting idea so I will try to frame the question. There is clear evidence that thermal vent animals have close symbiotic relationships with bacteria. The Pacific tubeworms are a good example. Also, much evidence exists that mitochondria in cells may have had free living prokaryotic ancestors who took up residence in one way or another in cells leading to today’s eukaryotes. So, is anyone talking about whether the symbiosis we see in the vent animals is a possible link to the development of energy converting organelles in modern cells?
Neil Glickstein,
Waring School, Beverly MA
Hi Neil:
Good to hear from you! Glad to hear that you and your class are enjoying Dive and Discover!
I asked Colleen Cavanaugh who works on symbiosis to answer your very interesting question. Here is her response:
The studies of modern symbioses do provide insights in to understanding the origin and evolution of eukaryotic organelles such as the mitochondria and chloroplasts, as well as looking at alternative energy sources that animals are able to exploit via their symbiotic bacteria. Indeed, we may be watching the evolution of “organelles” from free-living bacteria, through endosymbionts, to a bacterium no longer capable of a free-living existence, in the vent symbioses.
Since the original symbiosis of eukaryotes with aerobic bacteria (resulting in mitochondria) and cyanobacteria (resulting in chloroplasts) ancestors likely occurred more than a billion years ago, the symbioses we study at the vents, as well as many other modern symbioses (e.g., N2 fixing bacteria (rhizobia) that form root nodules with legumes/ plants), I would say they are excellent models, but not necessarily a “link”.
Colleen Cavanaugh
So -- there you have it! Hope you students will continue to send us questions -- there have been some good ones!
Cheers,
Susan
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