Animal Phyla

A Phylum (pl. Phyla) is the largest formal major grouping within animal taxonomy. This list is presented in alphabetical order, and not in any systematic/evolutionary arrangement. This list is also available in table form. Science is by no means static. There are arguments of all sizes and shapes about the taxonomy of the Animal Phyla. Other sources may combine or split these listed Phyla. However, at this time, the list presented here should stand in good stead for an introduction to the topic of animal diversity.

There are approximately 2 million animal species that have been described by science.

This list tries to give the following information on each Phylum:
 * Phylum Name
 * A link to a subpage discussing that Phylum in more detail (if it yet exists)
 * Name Meaning (in English)
 * An English Common Name, where one is in regular use
 * Distinguishing characteristics of animals within the Phylum
 * An approximate number of species described within that Phylum. Since zoology fortunately refuses to stand still, this number can change.

Oh! And there's a quiz at the end. See also /Lesson Plan for Animal Phyla/. Or head to Introduction_to_Taxonomy for more on that topic. You can also visit Plant Divisions (Phyla), the equivalent page for plants.

Acanthocephala
/Acanthocephala/

Name Meaning: Thorny head

English Common Name: Thorny-headed worms

Major distinguishing characteristics: Reversible spiny proboscis

Approximate number of species described: 1,151

Acoelomorpha
/Acoelomorpha/

Name Meaning: Without gut

English Common Name: Acoels

Major distinguishing characteristics: No mouth or alimentary canal

Approximate number of species described: 50,000

Annelida
/Annelida/

Name Meaning: Little ring

English Common Name: Segmented worms, annelids

Major distinguishing characteristics: Multiple circular segments

Approximate number of species described: 22,000 modern

Arthropoda
/Arthropoda/

Name Meaning: Jointed foot

English Common Name: Arthropods

Major distinguishing characteristics: Chitin exoskeleton

Approximate number of species described: 1,134,000+

Brachiopoda
/Brachiopoda/

Name Meaning: Arm foot

English Common Name: Lamp shells, brachiopod

Major distinguishing characteristics: Lophophore and pedicle

Approximate number of species described: between 300 and 500 extant

Bryozoa
/Bryozoa/

Name Meaning: Moss animals

English Common Name: Moss animals, sea mats, bryozoans

Major distinguishing characteristics: Lophophore, no pedicle, ciliated tentacles

Approximate number of species described: about 5,000 living species

Chaetognatha
/Chaetognatha/

Name Meaning: Longhair jaw

English Common Name: Arrow worms

Major distinguishing characteristics: Chitinous spines either side of head, fins

Approximate number of species described: about 100 modern species

Chordata
/Chordata/

Name Meaning: Cord

English Common Name: Chordates

Major distinguishing characteristics: Hollow dorsal nervous chord

Approximate number of species described: about 100,000+

Cnidaria
/Cnidaria/

Name Meaning: Stinging nettle

English Common Name: Coelenterates, cnidarians, sea anemones, jellies, hydra

Major distinguishing characteristics: Cnidocytes (stinging cells)

Approximate number of species described: about 11,000

Ctenophora
/Ctenophora/

Name Meaning: Comb bearer

English Common Name: Comb jellies, Ctenophores

Major distinguishing characteristics: Eight "comb rows" of fused cilia

Approximate number of species described: about 100 modern species

Cycliophora
/Cycliophora/

Name Meaning: Wheel carrying

English Common Name: Symbion

Major distinguishing characteristics: Circular mouth surrounded by small cilia

Approximate number of species described: at least 3

Echinodermata
/Echinodermata/

Name Meaning: Spiny skin

English Common Name: Echinoderms

Major distinguishing characteristics: Five-fold radial symmetry, mesodermal layer, calcified spines

Approximate number of species described: about 7,000 living species and 13,000 extinct ones

Entoprocta
/Entoprocta/

Name Meaning: Inside anus

English Common Name: Goblet worm

Major distinguishing characteristics: Anus inside ring of cilia

Approximate number of species described: about 150

Gastrotricha
/Gastrotricha/

Name Meaning: Hair stomach

English Common Name: Meiofauna

Two terminal adhesive tubes

Approximate number of species described: about 690

Gnathostomulida
/Gnathostomulida/

Name Meaning: Jaw orifice

English Common Name: Jaw worms

Major distinguishing characteristics:

Approximate number of species described: about 100

Hemichordata
/Hemichordata/

Name Meaning: Half cord

English Common Name: Acorn worms

Major distinguishing characteristics: Stomochord in collar

Approximate number of species described: about 100 living species

Kinorhyncha
/Kinorhyncha/

Name Meaning: Motion snout

English Common Name: Mud dragons

Major distinguishing characteristics: Eleven segments, each with a dorsal plate

Approximate number of species described: about 150

Loricifera
/Loricifera/

Name Meaning: Corset bearer

English Common Name: Brush heads

Major distinguishing characteristics: Umbrella-like scales at each end

Approximate number of species described: about 122

Micrognathozoa
/Micrognathozoa/ (sometimes called Phylum Gnathifera)

Name Meaning: Tiny jaw animals

English Common Name: Micrognathozoans

Major distinguishing characteristics: Accordion like extensible thorax

Approximate number of species described: 1

Mollusca
/Mollusca/

Name Meaning: Thin shell

English Common Name: Mollusks or molluscs

Major distinguishing characteristics: Muscular foot and Mantle, round shell

Approximate number of species described: 85,000

Nematoda
/Nematoda/

Name Meaning: Thread like

English Common Name: Round worms, Nematodes

Major distinguishing characteristics: Round cross section, keratin, cuticle

Approximate number of species described: 80 000 - 1 million

Nematomorpha
/Nematomorpha/

Name Meaning: Thread form

English Common Name: Horsehair worms

Major distinguishing characteristics:

Approximate number of species described: about 320

Nemertea
/Nemertea/

Name Meaning: A sea nymph

English Common Name: Ribbon worms

Major distinguishing characteristics:

Approximate number of species described: about 1200

Onychophora
/Onychophora/

Name Meaning: Claw bearer

English Common Name: Velvet worms

Major distinguishing characteristics: Legs tipped by chitinous claws

Approximate number of species described: about 200 modern

Orthonectida
/Orthonectida/

Name Meaning: Straight swim

English Common Name: Orthonectida

Major distinguishing characteristics:

Approximate number of species described: about 20

Phoronida
/Phoronida/

Name Meaning: Zeus' mistress

English Common Name: Horseshoe worms

Major distinguishing characteristics: U-shaped gut

Approximate number of species described: 20

Placozoa
/Placozoa/

Name Meaning: Plate animals

English Common Name: none

Major distinguishing characteristics:

Approximate number of species described: 1

Platyhelminthes
/Platyhelminthes/

Name Meaning: Flat worms

English Common Name: Flat worms

Major distinguishing characteristics:

Approximate number of species described: about 25,000

Porifera
/Porifera/

Name Meaning: Pore bearer

English Common Name: Sponges

Major distinguishing characteristics: Perforated interior wall

Approximate number of species described: over 5,000 modern

Priapulida
/Priapulida/

Name Meaning: Penis

English Common Name: Priapulid worms

Major distinguishing characteristics: Retractable proboscis surrounded by papillae

Approximate number of species described: 17

Rhombozoa
/Rhombozoa/

Name Meaning: Lozenge animal

English Common Name: Lozenge animals

Major distinguishing characteristics: Single axial cell surrounded by ciliated cells

Approximate number of species described: 75

Rotifera
/Rotifera/

Name Meaning: Wheel bearer

English Common Name: Rotifers

Major distinguishing characteristics: Anterior crown of cilia

Approximate number of species described: about 2000

Sipuncula
/Sipuncula/

Name Meaning: Small tube

English Common Name: Peanut worms

Major distinguishing characteristics: Mouth surrounded by invertible tentacles

Approximate number of species described: 144-320

Tardigrada
/Tardigrada/

Name Meaning: Slow step

English Common Name: Water bears

Major distinguishing characteristics: Four segmented body and head

Approximate number of species described: 1,000+

Xenoturbellida
/Xenoturbellida/

Name Meaning: Strange flatworm

English Common Name: none

Major distinguishing characteristics: Ciliated deuterostome

Approximate number of species described: 2

Quizzes

 * Animal Phyla Quiz