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The arthropods

Almost six hundred million years ago, long before vertebrates existed, some sea-dwelling animals evolved a hard, armor-like body covering, and things just haven't been the same since. Those organisms were the ancestors of insects, spiders, centipedes, millipedes, the extinct trilobites, lobsters, and their relatives — an enormously successful group of organisms known as arthropods. And for better or worse, all arthropods have inherited some basic characteristics of those first ancestors, including their armor-like body covering — the exoskeleton (exo = outside).

Fossil arthropods Modern arthropods
Naroia
Naroia
millipede
millipede
Waptia
Waptia
spider
spider
Habelia
Habelia
crab
crab
Leancholia
Leancholia
beetle
beetle



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Mantis shrimp shoulder their evolutionary baggage and bluff

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The exoskeleton: the good, the bad, and the creepy-crawly


Naroia, Waptia, Habelia and Leancholia fossil images by Chip Clark, Museum of Natural History, Smithsonian Institution; Millipede and beetle photos © 2004 Joyce Gross; Spider photo by Dr. Lloyd Glenn Ingles © California Academy of Sciences; Crab photo by Gerald and Buff Corsi © California Academy of Sciences

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You see them everywhere, now learn more: what is an arthropod?