Class Similar orders, in turn, are grouped into the next larger rank, a class. The order Artiodactyla is placed in the class Mammalia, which includes all animals that are warmblooded, have body hair, and produce milk for their young.

Phylum Classes are grouped into a phylum. A phylum includes organisms that are different but share important characteristics. The class Mammalia is grouped with birds (class Aves), reptiles (class Reptilia), amphibians (class Amphibia), and all classes of fish into the phylum Chordata. These organisms share important body-plan features, among them a nerve cord along the back.

Kingdom The largest and most inclusive of Linnaeus's taxonomic categories is the kingdom. All multicellular animals are placed in the kingdom Animalia.

An illustration shows a Bactrian camel is grouped with each taxonomic category.

FIGURE 18–5 From Species to Kingdom This illustration shows how a Bactrian camel, Camelus bactrianus, is grouped within each taxonomic category. Only some representative organisms are illustrated for each taxon above the genus level. Interpret Visuals What phylum does Camelus bactrianus belong to?

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Table of Contents

Miller & Levine Biology UNIT 1 The Nature of Life UNIT 2 Ecology UNIT 3 Cells UNIT 4 Genetics UNIT 5 Evolution UNIT 6 From Microorganisms to Plants UNIT 7 Animals UNIT 8 The Human Body A Visual Guide to The Diversity of Life Appendices Glossary Index Credits