The Animalia kingdom contains more than 9 million known species. These species can be sub-divided into two main groups – invertebrates (have no backbone) and vertebrates (most have backbones known as chordata).
Animal kingdom classification, or taxonomy, is a very important scientific system that helps us understand how all living organisms are related.
Animals are placed into groups based upon how many features they share. The more specific the features shared between animals, the more specific that animal classification group is.
Every species is defined based on nine branching categories. The primary method of animal classification is:
The term "phylum" is a level of classification, also known as taxonomic rank, that falls below kingdom and above class.
Using our Animal Encyclopedia, you can explore almost every known animal species that inhabit planet earth by browsing through the six main phyla classifications: Annelids, Arthropods, Chordates, Cnidarians, Mollusks, Nematodes.
Annelids – Annelids are a large phylum that contains over 22,000 species, including ragworms, earthworms, and leeches.
Arthropods – An arthropod is an invertebrate animal with an exoskeleton, a segmented body, and pairs of jointed appendages. These include insects, arachnids, and crustaceans.
Chordates – Chordates are animals that belong to the phylum Chordata, which includes vertebrates, the most highly evolved animals, and two other subphyla, tunicates and cephalochordates.
Cnidarians – There are over 11,000 species of aquatic animals in the phylum Cnidaria, including freshwater and marine animals. Their distinguishing feature is cnidocytes, which are specialized cells that they use to catch prey.
Mollusks – Mollusca, known as mollusks, is the second-largest phylum of invertebrates after Arthropoda. There are around 85,000 known species of mollusks in the world.
Nematodes -- Nematodes, or roundworms, form the phylum Nematoda. This animal phylum is diverse and inhabits a variety of environments.
Annelids are a large phylum that contains over 22,000 species, including ragworms, earthworms, and leeches.
Chordates are animals that belong to the phylum Chordata, which includes vertebrates, the most highly evolved animals, and two other subphyla, tunicates and cephalochordates.