Animal Diversity 7th Edition by Cleveland Hickman,Larry Roberts,Susan Keen ,Allan Larson,David Eisenhour

Exercise 1

Before the advent of modern phylogenetic methods, biologists thought that all unicellular eukaryotes were closely related to animals. Two terms, protozoan and metazoan, were used to describe the unicellular and multicellular animals, respectively. Why, in light of recent phylogeny, can we replace the term metazoan with animal?