How many animals were on Noah's ark?

According to Genesis 7
God said to Noah "Of every clean beast thou shalt take to thee by sevens, the male and his female: and of beasts that are not clean by two, the male and his female.
Of fowls also of the air by sevens, the male and the female; to keep seed alive upon the face of all the earth."
Cancel the Unicorns

Many sites (mainly creationist) go into great depth to show how few animals Noah would have had to take. This from the site below:

The author attacks the problems of the ark in a systematic fashion. He begins by calculating how many animals were on the ark. He uses the genera as the equivalent of the created kind. Taking one pair from each genera, living and fossil, he lists 7428 mammals, 4602 birds and 3724 reptiles on the ark. This totals to 15,754 animals on the ark.

http://www.talkorigins.org/faqs/woodmorappe-review.html