ABSTRACT

Mites and ticks are chelicerate arthropods with ancient origins. This chapter reviews the characteristics of arthropods and their taxonomic relationships and provides an overview of their evolutionary history. The phylum Arthropoda consists of at least 700,000 described species, or about 80% of the known animals of the world. Some estimate that more than 2 million arthropod species will be described eventually. Both in number of species and number of individuals, arthropods far surpass all other multicellular phyla in both numbers and diversity, exceeded only by the unicellular microbiota.