Naturespeak A naturalist's view of the world

April 13, 2009

Of Beaver Bugs & Woody Notes

Filed under: Uncategorized — wykes @ 8:35 pm

In the last blog entry, “The Master of Castor,” I ended things just as we were staring at the b-hole of a beaver.  This time, I’ll start there because it’s not a bad place to be. You see, apart from affairs of the  fur and that marvelous tail, the castor glands of the beaver are valid subjects in their own right. These paired glands, which produce what is known commercially as castoreum,  exit out of the beaver’s body at this point so the place can’t be avoided.

I won’t show you what the glands look like once they have been taken out, but if you can imagine a pair of prune-sized punching bags linked by a  flat leather strap you will have the basic idea. When a beaver is skinned, the glands are normally taken out and dried.  Most trappers will use the stuff as a lure, but there is another commercial use which brings these structures into the company of some pretty high society.

O.K., if you want to be anal about it, the castor glands are not really glands in the true biological sense of the word, but when hovering over the anus of a beaver one really doesn’t need to be anal does one? We can call them glands and the world will be alright.   In some circles they are called “beaver pods” as a way to make them sound fruity or non-anal, I guess. Whatever you call them, these structures exude a yellowish paste that smells like….well, a smell that is hard to describe.

 A freshly trapped beaver actually smells quite good – the slightly sweet castor oil smell hovering about the creature like an aftershave. In life, the beaver smears it about in order to mark territorial boundaries and consequently it’s fur becomes saturated with it. One German chemist classified the smell as “sharp and burning with a creosote or tar-like note, reminiscent of the glowing odor emanating from birch tar or Russian leather.”  Now, that really clears things up doesn’t it? Personally, I think it smells like bad Cinnamon. There is plenty of room for both of us to be right.

The oil is actually a chemical stew packed with over 24 identifiable compounds.  Most of these chemicals are Phenolic compounds and some “rather exotic nitrogen containing compounds,” but salicylic acid derivatives and cinnamic acid are also part of the brew. Cinnamic acid, as you might suspect, is a major component of Cinnamon! Why, you might ask, is so much known about this stuff? Castoreum has long been a major ingredient used by the perfume industry.

Only the highest quality perfumes use real castoreum oil in their mix, but many carry on the tradition by using a synthetic version. The original beaver castoreum were dried and aged for up to five years before they were used. Such classic perfumes as Emeraude, Coty Chanel, and Lancome Caractere are castor based. In the trade, these perfumes are classified as giving off leathery or woody notes, and I doubt you can get much more earthy than beaver musk.

Just when you think you’ve now heard it all, I have one more thing to throw at you. When examining the beaver which inspired all this enlightenment, I noticed a tiny creature walking all over the front paw (see here). I believed it to be a flea at first, but upon taking a closer look realized that I was in the presence of a Beaver Beetle. This extremely unique little insect (only 2 mm long) can only be found living on beavers. It essentially lives off of beaver dandruff and parasitic mites, so the relationship to it’s giant host is symbiotic and beneficial.

In the form of a simplified beetle without eyes or wings (see top view at beginning and underside view above), this flattened insect is fully adapted to crawling through dense fur. I found two of these creatures on this individual, but most beavers have many more beetles-in-residence. One study revealed 192 living on one animal alone.

So, Beavers have upon their back beaverbugs to ride ’em and upon their butts two beaver pods that smell quite indescribum.

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