According to current scientific estimates, there are approximately 8.7 million known species on Earth. However, it is important to note that this number is constantly changing as new species are discovered and described, and it is widely believed that there are many more species yet to be discovered, particularly in unexplored regions and ecosystems.
Regarding the number of species listed on Noah's Ark in the Bible, the specific number is not mentioned. The account of Noah's Ark in the Bible states that Noah was instructed by God to bring two of every kind of living creature, male and female, onto the ark to preserve them during the great flood. The Bible does not provide an exhaustive list of species or specify the exact number of species present at that time. The concept of "species" as understood in modern scientific classification did not exist during the time the story of Noah's Ark was recorded. The account is often interpreted more broadly as representing the preservation of biodiversity and the repopulation of the Earth.