The Success of Terrestrial Arthropods

Abstract

The Arthropoda and the vertebrates are usually regarded as the two most successful taxa so far to have evolved but, before we turn to consider the success of the terrestrial arthropods, the group with which this book is concerned, we should perhaps consider what is meant by successful. The marine crustacean Calanus finmarchicus has possibly the greatest biomass of any animal species, because it is adapted to planktonic life throughout the oceans of the world. It might, therefore, be regarded as more successful than Thermocyclops schuurmanni, which exists in the anoxic lower waters of a few small volcanic crater lakes in werstern Uganda — if we take biomass as the criterion of success. But is Calanus really more successful, or does it merely inhabit a larger environment?