Friday, 9 April 2010

Snottites anyone?

This post is inspired by the final episode of a brilliant new documentary series called Wonders of The Solar System which is presented by Professor Brian Cox of Manchester University. (You can find him on Twitter as @profbriancox). Until watching it I had never even heard of snottites so this is like a new discovery and exciting new learning experience for me. Thank you Prof. Cox for that!

So then, what on earth are snottites? Any chemist, geologist or person who likes to visit caves will undoubtably be familiar with stalagmites and stalactites. Those huge icicle like structures found in limestone caves which grow upwards from the cavernous floors and hang down from their ceilings. They are deposits of calcium carbonate, also known as calcite, which are formed because water rich in calcium carbonate drips through the ceilings of caves and thus onto the floor of the caves as well. As the water evaporates, it leaves behind  these deposits which slowly ‘grow’ giving stalactites that hang from the ceiling and stalagmites which build upwards from the cave floor. They take thousands and thousands of years to grow and are impressive to see and very many beautiful photographs of them have been taken.


This leads me on nicely to talk about snottites, which are also found hanging from the ceilings of caves. Their name is a clue to their characteristic features, namely they are rather more gluey and snot like than our calcium based friends. You could be forgiven for thinking that a giant bat had flown by and sneezed leaving its mucous gobbed all over the cave walls! So what exactly is this intriguing if disgusting looking stuff? Snottites consist of colonies of single celled extremophilic bacteria. Such extremophiles are so called because they can survive in conditions here on earth which would be hazardous if not fatal to human beings. They live in dark damp places beneath the surface of the earth and can live in extremes of temperature, pH etc. In sulfidic caves, these bacteria derive their energy out of the water which enters the caves from below or drips down from above. This water contains hydrogen sulphide which the bacteria metabolise using oxygen to produce energy and sulphuric acid as their main waste product. Thus snottites have a more fluidic consistency and are very acidic with a pH of between 0 and 1.

This photo courtesy of

Researchers are interested in studying the geochemistry of these microbes and understanding their sulphur cycle. There is now one much studied toxic sulphur cave in Mexico called Cueva de Villa Luz (Cave of the lighted house). This is the very same cave which Prof. Cox visited for ‘Wonders’ and is where these photo’s were taken. Snotites have also been found closer to home in some caves in Wales ;) I think a visit may be in order. Whilst I have seen stalactites and stalagmites, I have yet to see snottites. I don’t think I could bring myself to touch one though. As intriguing as they are, I mean yuk, just yuk! Perhaps I may change my mind on that if the times comes, all in the name of science and experience.

(photo credit: Dan S Jones-Penn State)

Interestingly,it is also not known where these microbes actually originate from. These organisms may perhaps be able to tell us more about the early microbes which existed on earth and even more excitingly, about the possibility of organisms which may live or have lived deep beneath the surface of other planets or moons such as Mars and Europa. Lets keep on investigating shall we? I hope you’ve enjoyed this journey. Thanks for staying with me through the gobs xxx

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