Slime: a natural history

Susanne Wedlich.
Slime: a natural history.
Granta. 2021

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Slime is ubiquitous in living systems: as glue holding bacterial mats together, as lubricant allowing us to swallow our food, as both glue and lubricant excreted by slugs and snails to travel on, and much much more.

In this fascinating book, Wedlich explores all things slime (or mucus, or even biological aqueous hydrogel to sound more formal, if less attention-grabbing). She covers our human reaction to slime (the ick factor), and its role in art and culture; the physics of slime and how it can be both glue and lubricant; slime in organisms, particularly bacteria; the role of slime in the origin and evolution of life; and the place of slime in our ecosystems. This is all utterly fascinating, with new revelations on nearly every page. I had thought I knew at least something about the various major processes in biology: after reading this, I feel as if I have discovered a whole new kingdom.

I learned a lot, not just about organisms and evolution, but unexpected aspects like the role of slime in deserts and sea surfaces, and how climate change threatens the delicate balance of this almost unrecognised but crucial component of our biome. Highly recommended.

[Disclaimer: I was given my copy of this, in preparation for my hosting a discussion with the author during the York Festival of Ideas 2022.]

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festive hats

Out for a walk this morning, I spotted that someone has made a festive decoration for a pillar box:

The base is knitted/crocheted; the decorations are felt-work.

I looked out for the next pillar box I passed, and sure enough:

Here the carol singers are also knitted, and some have clearly had a little too much mulled wine.

Thanks, mystery yarn-bomber, for raising a smile!

sequestering carbon, one Christmas at a time X

His ’n’ hers Christmas presents:

another year, another tree

Due to a variety of circumastances, we got our tree a bit later than usual this year.  The first place we went had only four tiddlers left.  Fortunately, the next place had a decent one.

thick ice

It has been below, or around, freezing for a while now, and there’s a lot of ice around.  Today I noticed that the ice in one of our garden water tubs has expanded about 1cm above the rim of the tub.

Looking at it, I wondered how thick the ice was in total, to give that amount of expansion.  And then, could I calculate the thickness from just this observation?  And could I calculate it without knowing the height of the tub?

So I drew a sketch:

On the right is the liquid situation: water to the brim of the tub (which it was before the freeze).  On the left is the current situation, the top x units of water frozen to make x+d units of ice.  That does indeed look independent of the depth of the tub (unless maybe it is all frozen, which I doubt).

Let’s assume both the ice and water are at 0°C.  Wikipedia tell us that ice has a 9% increase in volume over water, which means that d = 0.09 x.

Since the observed d = 1cm, this implies that x = 11cm (much less than the depth of the tub, so no need to worry about it being frozen through), and so the whole ice layer is about 12cm (nearly 5 inches) thick.

That’s a thick layer of ice!

that's no cat!

Caught on our webcam around lunchtime today.  

Reviewing the images, we initially thought it was the neighbour’s ginger tom Trevor, as he likes prowling round our garden.  But it looked a bit weird.

Then, a few shots further on, we could see its thin legs, and it turned its head.

It’s a deer!  In our garden!  We are not in the countryside: we are surrounded by houses.  Where did it come from?  Where did it go, after it trotted past the car?

sequestering carbon, several books at a time CXXVI

 It's been a while since the last update, so there are rather more in the pile than usual: