Acanthocephala

Thorny headed worms

Thorny-headed worms

Reversible spiny proboscis

approx. 756

Acoelomorpha

Without gut

Acoels

No mouth or alimentary canal (alimentary canal = digestive tract in digestive system)

Annelida

Little ring

Segmented worms

Multiple circular segment

17,000+ extant

Arthropoda

Jointed foot

Arthropods

Chitin exoskeleton

1,134,000+

Brachiopoda

Arm foot

Lamp shells

Lophophore and pedicle

300-500 extant

Bryozoa

Moss animals

Moss animals, sea mats

Lophophore, no pedicle, ciliated tentacles

5,000 extant

Chaetognatha

Longhair jaw

Arrow worms

Chitinous spines either side of head, fins

approx. 100 extant

Chordata

With a cord

Chordates

Hollow dorsal nerve cord, notochord, pharyngeal slits, endostyle, post-anal tail

approx. 100,000+

Cnidaria

Stinging nettle

Coelenterates

Nematocysts (stinging cells)

approx. 11,000

Ctenophora

Comb bearer

Comb jellies

Eight "comb rows" of fused cilia

approx. 100 extant

Cycliophora

Wheel carrying

Symbion

Circular mouth surrounded by small cilia

3+

Echinodermata

Spiny skin

Echinoderms

Fivefold radial symmetry in living forms, mesodermal calcified spines

approx. 7,000 extant; approx. 13,000 extinct

Entoprocta

Inside anus

Goblet worm

Anus inside ring of cilia

approx. 150

Gastrotricha

Hair stomach

Meiofauna

Two terminal adhesive tubes

approx. 690

Gnathostomulida

Jaw orifice

Jaw worms

approx. 100

Hemichordata

Half cord

Acorn worms, pterobranchs

Stomochord in collar, pharyngeal slits

approx. 100 extant

Kinorhyncha

Motion snout

Mud dragons

Eleven segments, each with a dorsal plate

approx. 150

Loricifera

Corset bearer

Brush heads

Umbrella-like scales at each end

approx. 122

Micrognathozoa

Tiny jaw animals

—

Accordion like extensible thorax

1

Mollusca

Soft

Mollusks / molluscs

Muscular foot and mantle round shell

112,000^[9]

Nematoda

Thread like

Round worms

Round cross section, keratin cuticle

80,000–1,000,000

Nematomorpha

Thread form

Horsehair worms

approx. 320

Nemertea

A sea nymph

Ribbon worms

approx. 1,200

Onychophora

Claw bearer

Velvet worms

Legs tipped by chitinous claws

approx. 200 extant

Orthonectida

Straight swim

Single layer of ciliated cells surrounding a mass of sex cells

approx. 20

Phoronida

Zeus's mistress

Horseshoe worms

U-shaped gut

11

Placozoa

Plate animals

1

Platyhelminthes

Flat worms

Flat worms

approx. 25,000^[10]

Porifera*

Pore bearer

Sponges

Perforated interior wall

5,000+ extant

Priapulida

Little Priapus

16

Rhombozoa

Lozenge animal

—

Single axial cell surrounded by ciliated cells

75

Rotifera

Wheel bearer

Rotifers

Anterior crown of cilia

approx. 2,000

Sipuncula

Small tube

Peanut worms

Mouth surrounded by invertible tentacles

144–320

Tardigrada

Slow step

Water bears

Four segmented body and head

1,000+

Xenoturbellida

Strange flatworm

—

Ciliated deuterostome

2

Total: 35

2,000,000-