The following is a list of the classes in each phylum of the kingdom Animalia. There are 108 classes of animals in 34 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.
Incertae sedis
- Micrognathozoa
Acanthocephala (thorny-headed worms)
- Archiacanthocephala
- Eoacanthocephala
- Palaeacanthocephala
Acoelomorpha (simple soft-bodied flatworms)
- Acoela
- Nemertodermatida
Annelida (segmented worms)
- Aelosomata
- Clitellata (earthworms)
- Myzostomida
- Polychaeta
- Echiura
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)
- Maxillopoda (barnacles, copepods, fish lice, and other groups)
- Ostracoda (seed shrimp)
- Remipedia (no common name)
Hexapoda
- Protura (coneheads)
- Diplura (two-pronged bristletails)
- Collembola (springtails)
- Insecta (insects)
Myriapoda
- Chilopoda (centipedes)
- Diplopoda (millipedes)
- Pauropoda (no common name)
- Symphyla (pseudocentipedes)
Brachiopoda (brachiopods aka lamp shells)
- Craniforma
- Lingulata
- Rhynchonellata
Bryozoa (moss animals)
- Gymnolaemata
- Phylactolaemata
- Stenolaemata
Chaetognatha (arrow worms)
- Archisagittoidea
- Sagittoidea
Chordata (vertebrates, tunicates, and lancelets)
Cephalochordata
- Leptocardii (lancelet)
Tunicata
- Appendicularia (larvaceans)
- Ascidiacea (sea squirts)
- Sorberacea (no common name)
- Thaliacea (salps, pyrosomes, and doliolids)
Vertebrata
Agnatha
Cyclostomata
- Myxini (hagfish)
- Petromyzontida (lamprey)
Gnathostomata
- Chondrichthyes (cartilaginous fish, mostly sharks and rays)
Tetrapoda
- Amphibia
Amniota
- Mammalia (mammals)
- Aves (birds)
- Reptilia (reptiles)
Osteichthyes
- Actinopterygii (ray-finned fish, which includes most familiar bony fish)
- Sarcopterygii (lobe-finned fish)
Cnidaria (jellyfish, corals, anemones, and others)
- Anthozoa (corals and anemones)
- Cubozoa (box jellyfish)
- Hydrozoa (hydroids and others)
- Malacosporea
- Myxosporea
- Scyphozoa (true jellyfish)
- Staurozoa (stalked jellyfish)
- Polypodiozoa
Cycliophora (tiny marine animals)
- Eucycliophora
Dicyemida (rhombozoan mesozoans)
- Dicyemida
Echinodermata (starfish, sea urchins, sand dollars, sea lilies, and others)
Crinozoa
- Crinoidea (sea lilies and feather stars)
Asterozoa
- Asteroidea (star fish)
- Ophiuroidea (brittle stars)
Echinozoa
- Echinoidea (sea urchins)
- Holothuroidea (sea cucumbers)
Entoprocta
- Entoprocta
Gastrotricha
- Gastrotricha
Gnathostomulida
- Gnathostomulida
Hemichordata
- Enteropneusta
- Pterobranchia
Kinorhyncha
- Kinorhyncha
Loricifera
- Loricifera
Mollusca
- Bivalvia (clams, mussels, scallops, and kin)
- Caudofoveata
- Cephalopoda (octopuses - see Octopus#Etymology and pluralization)
- Gastropoda (snails and slugs)
- Monoplacophora
- Polyplacophora
- Scaphopoda
- Solenogastres
Nematoda
- Adenophorea
- Chromadorea
- Secernentea
Nematomorpha
- Gordioidea
- Nectonematoida
Nemertea
- Anopla
- Enopla
Onychophora (velvet worms)
- Udeonychophora
Orthonectida
- Orthonectida
Placozoa
- Trichoplacoidea
Platyhelminthes (flatworms)
- Cestoda show characteristics of both cestodes and tremoteds
- Monogenea
- Trematoda flukes e.g. Clonorchis sinensis, Fasciola hepatica, schistosomes
- Turbellaria e.g. Dugesia
Porifera (sponges)
- Calcarea
- Demospongiae
- Hexactinellida
Priapulida
- Halicryptomorpha
- Priapulimorpha
- Seticoronaria
Rotifera (rotifers)
- Bdelloidea
- Monogononta
- Seisonidea
Sipuncula (peanut worms)
- Phascolosomatidea
- Sipunculidea
Tardigrada (tardigrades, water bears, or moss piglets)
- Eutardigrada
- Heterotardigrada
Xenoturbellida
- Xenoturbellida