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Nov 18, 2011


BarrytheBirder Photos

I shot the top photo today at a pond near my home in King City.   I was especially pleased to see that the picture clearly showed how perfectly the Muskrat's fur sheds water.   I took the second picture of a typical muskrat den last week, several miles west of the village.   The bottom photo I shot a couple of years ago and it shows a wintertime muskrat den with an open springtime foraging hole...a hole which is closed up at the end of each day.   Muskrats have been extensively studied and reported upon but I always wondered how they managed to chew and eat the underwater stems and roots of cattails and bulrushes without drowning.   Well now I know.   After some searching I came across the following on the Hinterland Who's Who website.   First of all, the Muskrat is capable of staying submerged for up to 15 minutes by reducing its heart rate and relaxing its muscles, thereby reducing oxygen usage.   It also stores oxygen in its muscles and is less sensitive to carbon dioxide levels in its blood than non-diving mammals.   Secondly, its front teeth are especially modified for underwater chewing.   Non-aquatic mammals, like you and me, would have great difficulty trying to chew on a large object under water, because the water would fill our mouth, throat and nasal passages.   The Muskrat has overcome this problem through the evolution of its cutting teeth, that protrude ahead of its cheeks and of lips that can close behind the teeth.   This permits the muskrat to chew on stems and roots under water with its mouth closed.   Nature is so adaptable.
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