Estimating the total number of species

• • As we have not yet discovered all the different species that exist it is not easy to estimate how many there are
  • however the past rate of discovery can be used as the basis for estimating the number
  • the gradual reduction in the rate of finding new species can be used to estimate the total number species that have not yet been discovered and therefore the total number of species that exist
• • New species are currently being discovered at a rate of about 20,000 per year
  • current estimates for the total number of species vary from 5 to 100 million
  • only two million species have been named so far
  • some ecosystems are so inaccessible, for example, the deep sea floor and the canopy of tropical rainforests that they have yet to be fully researched