With the winter cold biting and the snow setting in, most of us are unpacking our wellies and donning our warm winter coats. Humans seem to deal with the cold in lots of different ways, but how do small insects cope? I haven’t seen any birds or spiders scuttling about with a Barbour jacket or a pair of Hunter wellies, yet they face exactly the same conditions as humans when outside and when inside their homes they don’t have central heating and warm duvets to go
back to at the end of the day.
It’s worth pointing out that the cold is not actually the main threat to humans or animals when entering the outside world, it’s the ice! With water being a major component in cells and bodies, ice forming would mess about with the balance of fluids inside and outside of the cells, causing them to shrink and damage – which is about as bad for you as it sounds! Humans can just throw on
a jacket and although we might still feel the cold, we are mostly protected by using layers of clothing. Not all the natural world, including little insect, has this luxury.
Some insects like the Monarch butterfly have taken to escaping winter altogether by migrating to warmer climates, but most insects like spiders and beetles will stay in their local habitat, so they need to find other ways to avoid freezing. Crawling into holes and tunnelling beneath the frost line is
one option, but some insects and even fish have found an ingenious way of being able to cope with exposure to temperatures, by producing antifreeze.
Antifreeze is pretty remarkable; it’s basically a long repeating structure which lowers the minimum temperature that ice can form in the body by bonding to any ice crystals. About 120 species of fish have anti-freeze in their body to prepare them for life in the Polar Regions but there are also examples of
land creatures such as the snow flea (which to my surprise is not actually a flea) that have their own version of this anti freeze as well. Most insects you find in your back garden including spiders, beetles and ants have evolved a clever technique to prevent freezing by producing high concentrations of glycerol and other kinds of alcohol molecules, which slow ice formation down. This allows the fluid in the body to freeze in a more controlled way without the cells themselves freezing, so preventing damage to
the insect itself.
So if antifreeze is so useful, why is there not a human version or at least a developed injection we could take? Well because humans are warm-blooded, we maintain a body temperature that is higher than outside so injecting an antifreeze molecule into our bodies would be useless because we would not manage to survive if our body temperature dropped even a few degrees, let alone
to freezing point – isn’t that reassuring!
It seems humans will have to play the waiting game for a warm-blooded version of antifreeze and while we do, I think we can use the nature of evolution as an excuse to invest in some seriously expensive winter clothes!