How many species of animals are there?

As it's believed scientists are discovering new species on a daily basis, my bet is this number has significantly increased in the last three years! Truth be told, estimating (as that is all we can ever really do) the number of animal species that inhabit our planet is an exercise in educated guesswork ...and I'll try and tell you why!


1.) Habitats pose difficulties to scientists

It is extremely difficult to count and judge the number of animals because of their complicated and hard-to-reach locations. Think about those deep sea organisms for a second; they are not easy to access by a long stretch of the imagination and there could be endless amounts of animals deep routed in the dark depths of the sea bed, which we have never even seen! Likewise for those organisms that inhabit the depths of the earth, as well as the parasites that live on other organisms.


2.) Size can also obscure numbers

Moving on 'nicely' from parasites (if you can) is the idea that size can complicate the detection of species too. There must be thousands of species that we don't know about because we just can't see them!


3.) Ambiguities in classification

How do you define a species anyway? It's not always easy, especially when you consider cross breeds. If the scientists don't agree then who is the larger body to tell them otherwise? Well, there isn't one: you might read in one book that what you thought was a bird (perhaps due to a TV program you watched when you were 10) is actually classed as a reptile!


Despite these challenges, it is valuable for us humans (a mere single species) to have some idea of how many other species inhabit our planet: it provides us with knowledge, perspective and a better understanding of community structure and dynamics.
Coming back to this rather large number of 8.7 million reported by the BBC back in 2011 ...apparently this figure is described by scientists as the most accurate number to date. However, as the article goes on to say "BUT the vast majority have not been identified - and cataloguing them all could take more than 1,000 years." Whilst many may find this unnerving, I actually find it secretly thrilling as it means we are not 'the superior race' - how can we be if we never really know all there is to know about the millions (possibly billions) of other species that also inhabit our World.