Arthropod evolution and phylogeny

Article By:

Martin, Joel W. Invertebrate Zoology Section, Research and Collections Branch, Natural History Museum of Los Angeles County, Los Angeles, California.

Last reviewed:2013

DOI:https://doi.org/10.1036/1097-8542.YB133337

It is not an exaggeration to say that life on Earth is predominantly arthropodous. By any criteria, arthropods (members of the phylum Arthropoda) are the dominant metazoans (multicellular animals) on the planet, and this has been true for hundreds of millions of years. This dominance is evident in terms of the number of described species, global biomass, ecological importance, economic impact, and numerous other categories. Arthropods constitute more than 85% of all known species on Earth, and they have the richest fossil record of any animal group. Some typical arthropods are insects, spiders, ticks, and crustaceans. Of course, in additional to the numerous described species, the number of undescribed species of arthropods remains unknown. Arthropods dominate not only in number of species but in number of individual organisms: for example, who could begin to estimate the number of ants on the planet, or the number of copepods in the world's oceans?

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