How many animals are there in the world?

Question

How many animals are there in the world?

Answer 1

You've got two good answers there already. Assuming by "animal" you mean members of the phylum "animalia", I can tell you that the total volume of all animals in the class "Insecta" is greater than all other classes combined. Considering that insects are rather small compared to Vertebrates, the total number of animals must be a huge number!

If you really want to know, you should be asking this question under Biology, not Geology.

Answer 2

It depends on your definition of an "Animal"

For instance, are single celled creatures plants or animals?

The weight of single celled creatures is 10 times the weight of everything else.  There are trillions upon trillions of single celled creatures.

Answer 3

There is no solid answer for this question.

There is over 6 billion people in the world, there are a lot more animals in the world.