I wouldn't hold my breath..

  That's about as corny as I could think of for a title, but it will have to do.
Something talked about around the campfire a few times is the topic of drowning beaver. It's been mentioned on occasions that beaver , technically, do not drown. Although for hundreds of years trappers have always used the word, it is true that a beaver doesn't technically drown, instead he suffocates. For those who want to really be scientific you can enroll in med school and take this as far as you like, but a basic understanding of the beaver's anatomy should be enough.
 One book I've been reading on is The American Beaver and His Works , by Lewis Henry Morgan.
 Morgan goes into detail on the anatomy, and might be somewhat boring to most of us, but it does explain well what is happening when a beaver "drowns".
    A beaver we all know holds his breath under water, he is equipped with valve like organs that shut off his nose, and also his ears. His eyes also have a transparent lens that comes down when he makes a dive. Surprisingly a beaver actually has a small set of lungs, proportional to his body size, but it should make sense that because his metabolism is slow he does not need rapid oxygen replacement. Muskrat and otter have a larger set of lungs, in proportion, but they are more active and need larger volumes of oxygen.
  When a beaver is trapped, instinct drives him to deeper water below the surface, those valves shut and he takes in no oxygen, and of course no water to fill his lungs. The more he thrashes about, the more stored oxygen he uses up, and soon he asphyxiates.
   Technically it's not drowning, but technically it's all the same , lack of oxygen.
 So it's not exactly a misnomer when the trappers say "drown a beaver", and it would be strange to hear our trappers say something like "asphyxiation" and of course we are looking for the trappers word over a doctor of medicine for our endeavor.
  It might be good to note that few people are in agreement on how long a beaver can hold his breath, obviously it varies with each individual animal, and ranges from 10 minutes to 30 minutes. Some trappers claim as much as 45 minutes, which surprises the science guys as well as many other trappers.