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The Arthropod Story Table of Contents   

The five branches of the arthropod tree

Modern arthropods include insects, spiders, centipedes, shrimp, and crayfish. All arthropods are the descendents of a single common ancestor. Just as you and your biological cousins can trace your ancestry back to a common set of grandparents, all arthropods can trace their ancestry back to a common arthropod ancestor. Any species descended from that ancestor is an arthropod. And any species not descended from that ancestor is not an arthropod.

the arthropod tree

Millipede photo © 2004 William Leonard; Tarantula photo by Dr. Antonio J. Ferreira © California Academy of Sciences; Sally Lightfoot Crab photo by Gerald and Buff Corsi © California Academy of Sciences; Whitelined Sphinx Moth photo by T. W. Davies © California Academy of Sciences.

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