List of animal classes

The following is a list of the classes in each phylum of the kingdom Animalia. There are 107 classes of animals in 33 phyla in this list. However, different sources give different numbers of classes and phyla. For example, Protura, Diplura, and Collembola are often considered to be the three orders in the class Entognatha. This list should by no means be considered complete and authoritative and should be used carefully.

Unknown phylum

 * Micrognathozoa

Acanthocephala (thorny-headed worms)

 * Archiacanthocephala
 * Eoacanthocephala
 * Palaeacanthocephala (ancient thornheads)

Acoelomorpha (simple soft-bodied flatworms)

 * Acoela
 * Nemertodermatida

Annelida (segmented worms)

 * Aelosomata
 * Clitellata (earthworms)
 * Myzostomida
 * Polychaeta (bristle worms)
 * Echiura (spoon worms)
 * Sipuncula (peanut worms)

Arthropoda (arthropods: insects, crustaceans, arachnids, centipedes, and millipedes)
===Chelicerata ===
 * Arachnida (spiders, scorpions, and kin)
 * Xiphosura (horseshoe crabs; only 4 extant species)
 * Pycnogonida (sea spiders)

===Crustacea ===
 * Branchiopoda (fairy shrimp, tadpole shrimp, water fleas, and clam shrimp)
 * Cephalocarida (horseshoe shrimp; only 12 described species)
 * Malacostraca (crabs, lobsters, crayfish, krill, various shrimp, woodlice, and kin)f
 * Maxillopoda (barnacles, copepods, fish lice, and other groups)
 * Ostracoda (seed shrimp)
 * Remipedia

===Hexapoda ===
 * Entognatha (coneheads, two-pronged bristletails and springtails)
 * Insecta (insects)

===Myriapoda ===
 * Chilopoda (centipedes)
 * Diplopoda (millipedes)
 * Pauropoda
 * Symphyla (pseudocentipedes)

Brachiopoda ("lamp shells")

 * Craniforma
 * Lingulata
 * Rhynchonellata

Bryozoa (moss animals)

 * Gymnolaemata
 * Phylactolaemata
 * Stenolaemata

Chaetognatha (arrow worms)

 * Archisagittoidea
 * Sagittoidea

Cephalochordata

 * Leptocardii (lancelet)

Tunicata

 * Appendicularia (larvaceans)
 * Ascidiacea (sea squirts)
 * Sorberacea
 * Thaliacea (salps, pyrosomes, and doliolids)

Cyclostomata

 * Myxini (hagfish)
 * Petromyzontida (lampraey)

Gnathostomata

 * Chondrichthyes (cartilaginous fish, mostly sharks and rays)

Tetrapoda

 * Amphibia (amphibians)
 * Amniota
 * Mammalia (mammals)
 * Aves (birds)
 * Reptilia (reptiles)

Osteichthyes

 * Actinopterygii (ray-finned fish, which includes most familiar bony fish)
 * Sarcopterygii (lobe-finned fish)

Cnidaria (marine stinging animals)

 * Anthozoa (anenomes and corals)
 * Cubozoa (box jellyfish)
 * Hydrozoa (hydroids)
 * Malacosporea (marine parasites)
 * Myxosporea (marine parasites)
 * Scyphozoa (true jellyfish)
 * Staurozoa (stalked jellyfish)
 * Polypodiozoa (marine parasites)

Cycliophora (tiny marine animals)

 * Eucycliophora

Dicyemida (rhombozoa)

 * Dicyemida

Crinozoa

 * Crinoidea (sea lilies and feather stars)

Asterozoa

 * Asteroidea (star fish)
 * Ophiuroidea (brittle stars)

Echinozoa

 * Echinoidea (sea urchins)
 * Holothuroidea (sea cucumbers)

Entoprocta

 * Entoprocta

Gastrotricha (hairybacks)

 * Gastrotricha

Gnathostomulida (jaw worms)

 * Gnathostomulida

Hemichordata

 * Enteropneusta (acorn worms)
 * Pterobranchia

Kinorhyncha (mud dragons)

 * Kinorhyncha

Loricifera

 * Loricifera

Mollusca (mollusks)

 * Bivalvia (clams, mussels, scallops, and kin)
 * Caudofoveata
 * Cephalopoda (octopuses, squids and cuttlefish)
 * Gastropoda (snails and slugs)
 * Monoplacophora
 * Polyplacophora (chitons, or sea cradles)
 * Scaphopoda (tusk shells)
 * Solenogastres

Nematoda (roundworms)

 * Adenophorea
 * Chromadorea
 * Secernentea

Nematomorpha (horsehair worms)

 * Gordioidea
 * Nectonematoida

Nemertea (ribbon worms)

 * Anopla
 * Enopla

Onychophora (velvet worms)

 * Udeonychophora

Orthonectida

 * Orthonectida

Placozoa

 * Trichoplacoidea

Platyhelminthes (flatworms)

 * Cestoda (tapeworms and relatives)
 * Monogenea
 * Trematoda (flukes)
 * Turbellaria (e.g. Dugesia)

Porifera (sponges)

 * Calcarea (calcareous sponges)
 * Demospongiae
 * Hexactinellida (glass sponges)
 * Homoscleromorpha

Priapulida (priapulid worms)

 * Halicryptomorpha
 * Priapulimorpha
 * Seticoronaria

Rotifera (rotifers)

 * Bdelloidea
 * Monogononta
 * Seisonidea

Tardigrada (tardigrades, water bears, or moss piglets)

 * Eutardigrada
 * Heterotardigrada

Xenoturbellida

 * Xenoturbellida