I ran across an interesting project the other day from photographer Mark Menjivar entitled "You Are What You Eat". In it, he went to various people's homes, too pictures of the inside of their refrigerators or freezers, and gave a little bit of information about the people who owned the items in the photograph. It's a great series, and I recommend looking through the photos.
I saw one, in particular, of a Short Order Cook from Marathon, TX. I asked my Twitter followers to check it out, and to pay attention to the upper-right-hand corner, where they saw, well, a snake. Here's a better view.
This generated a fair range of reactions to Twitter, including one from Jenni Field, who after being silent enough for crickets to be heard, asked:
Now, I don't have a lot of experience with snakes, but I know some stuff about freezer burn. Freezer burn is an evocative term for the drying of food when it's in the freezer. Surface patches of frozen items become shriveled and discolored and a big collection of ice forms on top of it. It's not really a burn, of course, but you can't get rid of imagery like that. So what's going on? It's all about crystals and the nature of temperature.
We've talked temperature before, but to quickly sum up: temperature is a measurement of the average speed of the movement of molecules. The only temperature at which there is no molecular motion is absolute zero, also known as 0 Kelvin or roughly -273°C. Your freezer usually stores food closer to 0°C. Water boils at about 100°C. This means, motion wise, food in your freezer is more like boiling water than it is completely devoid of molecular motion. In other words, molecules are still moving around, even though water is technically "frozen."
Another thing to consider is that water inside of food is usually not alone. An ice cube is, more or less, just water. A steak is filled with a bunch of water, but it also has sugars, proteins, amino acids, and other goodies, much of which is dissolved in the water. This extra stuff in the water keeps the water from forming a stable crystal. This gives it more opportunity to move around. When the water happens to reach the surface of the food, if there is open air on top of it, the water will start to form a crystal. Once you have a crystal started, it's easy for additional water to add on. Once water is in a crystal, it's much less likely to leave, even though it's at the same temperature.
So you may be wondering what is so special about a crystal that makes it so stable. Think of molecules like Tinkertoys.
With a Tinkertoy, the wooden cylinder with the holes in it represent the molecules, and the sticks represent molecular bonds. You can put these molecules in all sorts of arrangements. Most of these arrangements, if you wiggled them or moved them, would fall apart or change shape pretty quickly. There are a few arrangements where the Tinkertoys are extremely stable. These stable arrangements are crystals. You can keep growing them and, as long as they keep forming the pattern that remains stable, it takes a lot of effort to break the arrangement.
So, water goes from its less stable fluid state inside of food, where it can't form a crystal, to a stable crystal outside of the food. The rest of the food dries out, and you get freezer burn.
So: the snake! When you look at the snake, you see that the skin is on pretty tight, so there are no gaps between the skin and the meat. This is as you would expect. Also, the eyes and mouth are closed, so there's no place for water to escape there. And snakes are cold-blooded, meaning they don't generate their own heat. Their problem is getting heat into their system, not getting it out of the system the way warm-blooded animals so. This means that they don't need to sweat in order to reduce their body heat, thus they don't need pores. This makes a snake's skin extra water-tight, so water is unlikely to escape that way.
Incidentally, I had a brief conversation with the photographer, Mark Menjivar, about this photo. He says that the snake is not destined for food, but rather is meant to be a walking stick. The woman found the snake already dead on the road, and decided to be crafty with it.