This image symbolically portrays the relative abundances of various life forms on earth. Each organism in the drawing represents a group of species, or taxon, in the real world, and the size of each organism in the drawing is proportionate to the number of species in that group.

This is a taxonomic view of life on earth -- based on systematic classifications -- which challenges our typical "mammal-centric" understanding of the world around us. Today there is increasing awareness of the enormous diversity of life on earth, but few people probably appreciate the fact that the Species-Scape is completely dominated by multilegged (more than 4 legs) and legless animals, fungi and microbes. Mammals, with a mere 4,000 species, are dwarfed by "lower" animals. These relationships are demonstrated with visual immediacy in the Species-Scape.

Proportions in the drawing, by scientific illustrator Frances L. Fawcett and Professor Quentin Wheeler (see Contributors), are based on approximate numbers of species described to date. The giant black beetle representing all insects, for example, reflects just under 800,000 species. However, entomologists believe that the total number of living insects may be as high as 5 - 10 million or more!

The number of species in each taxon may be impacted, too, by the concept of "species" employed. According to the Phylogenetic Species Concept, for example, the number of birds would double approximately, while the number of insects would be little affected.

It should be noted that some taxa, like reptiles, are here by convention, and today are not believed to be descended from a unique ancestor. And for all but a handful of taxa, their actual size is uncertain.

The exploration, description and formal classification of biological diversity is the purview of taxonomy or systematic biology.