Here's how I learned it in 1957:

Be kind to your web-footed friends
For a duck may be somebody's mother
They live in the marsh & the swamp
And wherever it may be damp
You may think that this is the end
Well, it is.....

You can't imagine what an impact this had on me at age 5. I always credit (blame?) this song for introducing me to absurdist humor, a trait I have passed on to my daughter.