Monday, October 29, 2012

Snakes in the freezer

My husband holding a rattlesnake
- he tells me he know what he is doing
In addition to tasty delights, my freezer often ends up the temporary home for animals that have died and are on their way to join the scientific collection at the local museum where my husband is a curator. It is sad that these animals have died, especially since it is often the result of humans like getting hit by a car or birds not seeing windows. At least collecting them puts them to good use - plus it prevents having to kill animals for science. I only accept the recently dead - I’ve put my foot down against rotting carcasses after a unpleasant decomposed swan incident. We’ve temporarily housed various song birds, a mink, a hawk, owls, wall lizards, newts, garter snakes, squirrels, toads and more. Perhaps a spare freezer in the carport would not be amiss.

Half a days drive from the coast can put me in rattlesnake country. Only once, have I seen a wild rattlesnake. It was so young it only had its button rather than a full rattle. It looked small and helpless when we cornered it on the bank of a stream. Then it put on an aggressive display, striking at us with it’s mouth open. We could clearly see its fangs, but managed to stay clear of them. We thought it was harmless, only later did I discover that baby rattlesnakes have very potent venom.

What makes a rattlesnake scary is its venom. Venom is saliva that has been modified over evolutionary time. It contains a complex assortment of components that differ between snake species. According to Munekiyo and Mackessy (1998) : “lethality of venom results from a synergistic interplay of venom components, including enzymes, peptides and specific toxins.”

The venom of a Fer de Lance acts differently than rattlesnake venom, which is why it is important to identify the snake that bit you - so you can get the right antivenin.

Snake venom is on my mind because my husband and I recently went to rattlesnake country. My husband has a long history of picking up rattlesnakes - including, Prairie, Eastern Massasauga, Timber, Dusky Pigmy, Northern Pacific Rattlers, and Eastern and Western Diamondbacks. So I was expecting a road-killed rattlesnake to come home with us and spent time in the freezer. I started to wonder if frozen rattlesnake venom is still toxic.

Fortunately, the toxicity of frozen rattlesnake venom has been studied by researchers (Munekiyo and Mackessy, 1998) looking at how to best preserve the venom for scientific research. The answer is yes, a frozen rattlesnake’s venom is still toxic - I’ll need to handle them with care. Munekiyo and Mackessy (1998) went on to speculate that their results should apply to all front-fanged snake venoms (both vipers/rattlesnakes and cobras and their relatives have front fangs). However, this still needs to be studied. I won’t worry about it as I don’t expect a cobra in my freezer - although I wouldn’t be surprised if I found one there. Presumably a cobra in the house would arrive with some warning or at least a big colourful sticky note on the freezer lid.

Reference: Munekiyo, S.M., and S.P. Mackessy. 1998. Effects of Temperature and Storage Conditions on the Electrophoretic, Toxic and Enzymatic Stability of Venom Components. Comp. Biochem. Physiol. 119B, 119-127.

Thanks to G. Hanke for the photos

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