The ark is one of those things christians should avoid mentioning, especially if it is going to be subjected to some bsic scrutiny.
It is one of the many examples of just outrageous events in the bible. Mark Twain makes a wonderful sketch in his "The God of the Bible vs. the God of the Present Day". The whole scheme, according to Twain was a complete waste of time and man/woman power. If he did not like his creation and needed to start from scratch, he could have simply wiped every creature and re-make them in six days again.
But, even if asume the lesson was worth teaching, the very possibility of having every single species represented in that boat was just impossible.
Most chrirtians I know would rather take that symbolically, and yet we have pastors like the one mentioned here going into the details of the daily manure disposal. Very clever