Witches Butter

Nostoc commune

Is it a fungus? Is it an algae? When I first came across this strange toffee coloured, jellied mass covering the entire roof of a garage complex, I had no idea what it was. At first I thought it was an algae, especially as most of it appeared to be thriving in pools of stagnent water, and then finally decided it must be some species of jellied fungus. I was also reminded of an old movie called The Blob starring Steve McQueen, but I was wrong on all accounts. After some Google investigations I discovered to my utter surprise that it is in fact a bacteria, a cyanobacterium to be precise.

Once classed as an alga, and now a cyanobacterium (photosynthetic bacterium) which has no nuclei or internal membrane systems, this microorganism is also called ‘Star Jelly’ or ‘Mare’s Eggs’. It is bluish-green, olive-green or brown in colour, and it forms a gelatinous mass with other colonies close by. When wet it has the appearance of a slippery convoluted blob, and when dry it shrivels and becomes wrinkled and unsightly. Witches Butter can fix nitrogen from the atmosphere and can therefore live in locations where no nitrogenous compounds are available from the substrate. It does not have chloroplasts but contains photosynthetic pigments in the cytoplasm of the cells. It also contains pigments that absorb long and medium wavelength ultraviolet radiation, which enables it to survive in places with high levels of radiation. To multiply, it forms two new cells when they divide by binary fission.

Witches Butter is very adaptable to different habitats and environments and is a very successful species. It is able to survive in extreme conditions of cold and dryness, and is both a terrestrial and freshwater species. It can remain dormant for an extended period of time and revive when conditions improve and water becomes available. The desiccated colony is resistant to heat and to repeated patterns of freezing and thawing. It can be found growing on man-made structures like roofs and pavings in urban environments, on gravels and amongst mosses. It is particularly associated with limestone, coral and other calcium-carbonate-based rocks. Also found in parks, fields, gardens and lawns, where it can suddenly appear after rain as if from nowhere, giving the impression it had just fallen from the sky, as if from a shooting star. A common and widespread species. Cyanobacteria created the conditions in the Earth’s early atmosphere that aided the evolution of the higher oxygen-using organisms that came after them. They are also very important contributors to the planetary biosphere’s current carbon and nitrogen levels.

Photographs taken September 2013, urban garage block, Staffordshire.

6 thoughts on “Witches Butter

  1. A garage roof? At first glance I thought it was some sort of marine seaweed. And it does look like toffee. (I don’t suppose you tasted it!)

    Liked by 1 person

    1. I couldn’t believe it when I saw this. There was about four garages which must have had a drainage problem on the roofs were covered in water, and they were or alive with this blob thing growing all over them. And I sure did not taste it lol!

      Liked by 1 person

      1. Ahh, well, I was just passing by on one side where the ground level was quite high, but I hadn’t got my camera that day. So, always fascinated by what wonders nature present to us, I had to return and get a few pics!

        Liked by 1 person

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