SNAKES AND GECKOS, OH MY!

By Pam Eastlick

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.

Greetings everyone, I thought we’d dip into the animal file today for a couple of stories that have local implications. Our first one is about those legless creatures that no one’s fond of: snakes. We all know that most poisonous snakes are ‘pit vipers’ which means they have hollow fangs that work just like hypodermic needles to inject the venom. This is one of the reasons the brown tree snake isn’t considered dangerous, because it isn’t a pit viper. Scientists have done some research however, and discovered that what we all ‘know’ just may be wrong! Read on!

Researchers from the University of Massachusetts have discovered that only about one seventh of all venomous snakes rely on the trick with the hollow fang. A typical representative of this group is the rattlesnake that uses its twin fangs to punch holes in the skin of its victims and injects the venom through the holes. But it turns out most snake species have discovered a groovier solution. Their fangs have a groove on the outside that allows venom to flow into the wound.

But this makes no sense when you realize that fur or bird feathers should simply prevent the venom from flowing into the wound. So how do they do it? The answer seems to be that snake venom is amazingly viscous, with a surface tension about the same as that of water. As a result, the surface energy pulls the venom into the fang grooves, where it then flows into the wound. Snakes that prey on birds developed deeper grooves to keep the viscous venom from being brushed away by bird feathers.

When a snake attacks, the fang grooves and the surrounding tissue form a canal. Just like blotting paper, the tissue sucks the venom through this canal. Snake venom also has a very special property to facilitate this effect. You shake the ketchup bottle to make it more liquid so it will come out of the bottle, and in a similar fashion, the shear forces that arise from the suction cause the venom to become less viscous, allowing it to flow through the canal quickly.

Scientists refer to substances with these characteristics as non-Newtonian fluids. These have a very practical consequence for snakes: As long as there is no prey in sight, the venom in the groove remains viscous and sticky. When the snake strikes, the venom becomes more liquid and it flows along the groove and into the wound, where the venom takes its lethal effect.

Having been bitten several times by brown tree snakes, I can testify that their venom is fast-acting and painful. And since they’re bird predators, although I’ve never peered into the mouth of one, I suspect their teeth have those tell-tale nasty little grooves!

The groove in a snake fang (Credit: Bruce A. Young, University of Massachusetts, Lowell)

And in another story with local implications; researchers at the University of Iowa have discovered a bacterium with an unusual appetite. It uses caffeine for food. It’s called Pseudomonas putida and it breaks caffeine down into carbon dioxide and ammonia.

Caffeine contains carbon, nitrogen, hydrogen and oxygen, all necessary for bacterial cell growth. This is important because tests show that compounds formed during the bacterial breakdown of caffeine are natural building blocks for drugs used to treat asthma, improve blood flow and stabilize heart arrhythmias. Another potential application is the decaffeination of coffee and tea as an alternative to the harsh chemicals currently used.

So why does this have local implications? Well, I’m not sure about the bacteria, but there are at least three geckos in my bedroom that are crazy about caffeine in the form of the spilled coffee in my saucer. So it isn’t just the humans and the bacteria that are addicted to caffeine!