# 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.

## Acanthocephala (thorny-headed worms)

* Archiacanthocephala
* Eoacanthocephala
* Palaeacanthocephala (ancient thornheads)
* Polyacanthocephala

## Acoelomorpha (simple soft-bodied flatworms)

* Acoela
* Nemertodermatida

## Annelida (segmented worms)

* Clitellata (earthworms)
* Polychaeta (bristle worms)
* Sipuncula (peanut worms)

## Arthropoda (arthropods: insects, crustaceans, arachnids, centipedes, and millipedes)
### Chelicerata

* Arachnida (spiders, scorpions, and kin)
* Xiphosura (horseshoe crabs)
* Pycnogonida (sea spiders)

### Crustacea

* Branchiopoda (fairy shrimp, tadpole shrimp, water fleas, and clam shrimp)
* Cephalocarida (horseshoe shrimp)
* Pentastomida (tongue worms)
* Branchiura (fish lice)
* Mystacocarida
* Copepoda
* Ostracoda (seed shrimp)
* Malacostraca (crabs, lobsters, crayfish, krill, various shrimp, woodlice, and kin)
* Thecostraca (barnacles)
* Remipedia

### Hexapoda

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

### Myriapoda

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

## Brachiopoda ("lamp shells")

* Lingulata
* Craniata
* Rhynchonellata

## Bryozoa (moss animals)

* Gymnolaemata
* Phylactolaemata
* Stenolaemata

## Chaetognatha (arrow worms)

* Sagittoidea

## Chordata (vertebrates, tunicates, and lancelets)
### Cephalochordata

* Leptocardii (lancelet)

### Tunicata

* Appendicularia (larvaceans)
* Ascidiacea (sea squirts, paraphyletic with respect to Thaliacea)
* Thaliacea (salps, pyrosomes, and doliolids)

### Vertebrata
#### Agnatha
##### Cyclostomata

* Myxini (hagfish)
* Petromyzontida (lamprey)

#### Gnathostomata

* Chondrichthyes (cartilaginous fish: chimeras, sharks and rays)
* Osteichthyes
** Actinopterygii (ray-finned fish, which includes most familiar bony fish)
** Sarcopterygii
*** Actinistia (coelacanths)
*** Dipnoi (lungfish)
*** Tetrapoda
**** Amphibia (amphibians)
**** Amniota
***** Mammalia (mammals)
***** Aves (birds)
***** Reptilia (reptiles, paraphyletic with respect to Aves)

## Cnidaria (marine stinging animals)

* Octocorallia
* Hexacorallia
* Ceriantharia
* Cubozoa (box jellyfish)
* Hydrozoa (hydroids)
* Myxozoa (marine parasites)
* Scyphozoa (true jellyfish)
* Staurozoa (stalked jellyfish)
* Polypodiozoa (marine parasites)

## Cycliophora (tiny marine animals)

* Eucycliophora

## Dicyemida (rhombozoa)

* 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 (hairybacks)

* Gastrotricha

## Gnathostomulida (jaw worms)

* Gnathostomulida

## Hemichordata

* Enteropneusta (acorn worms)
* Pterobranchia

## Kinorhyncha (mud dragons)

* Allomalorhagida
* Cyclorhagida

## Loricifera

* Loricifera

## Mollusca (mollusks)

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

## Micrognathozoa

* Micrognathozoa

## Nematoda (roundworms)

* Chromadorea
* Enoplea
* Secernentea

## Nematomorpha (horsehair worms)

* Gordioidea
* Nectonematoida

## Nemertea (ribbon worms)

* Hoplonemertea
* Palaeonemertea
* Pilidiophora

## Onychophora (velvet worms)

* Onychophora

## Orthonectida

* Orthonectida

## Placozoa

* Polyplacotomia
* Uniplacotomia

## 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