Subkingdom Eumetazoa

These animals have tissues organized into organs; the organs are usually organized into systems.

Phylum Cnidaria, or Coelenterata

Bodies saclike. Tentacles with stinging cells. Solitary or colonial. Mainly marine. Examples: coral, jellyfish.

Phylum Ctenophora

The comb jellies. Similar to cnidarians, but with comblike rows of cilia. Marine, solitary. Example: Venus's girdle.

Phylum Mesozoa

Microscopic wormlike parasites. Have only one organ: a gonad.

Phylum Platyhelminthes

The flatworms. Flat, slender bodies. Aquatic, terrestrial, or parasitic. .

Phylum Nemertina, or Rhynchocoela

The ribbon worms. Flat, slender bodies. Proboscis may extend to several times the length of the body. Mainly marine or terrestrial.

Phylum Gnathostomulida

Microscopic marine worms. Hermaphrodites. Have comblike feeding structures.

Phylum Rotifera

The rotifers. Head with crown of cilia. A variety of body shapes, ranging from trumpetlike to spherical. Aquatic. Most free-living; some parasitic.

Phylum Gastrotricha

Bodies wormlike, covered with spines; two rows of cilia. Aquatic.

Phylum Kinorhyncha

Wormlike; appear segmented because of zonites (rings). Pull themselves along with head spines. Marine.

Phylum Nematoda

The roundworms. Slender, cylindrical bodies. Aquatic or terrestrial; mainly freeliving but some parasitic.

Phylum Nematomorpha

The hairworms. Extremely slender bodies. Adults aquatic or terrestrial. Larvae parasitic.

Phylum Loricifera

Microscopic; rotifer-like. Retractable spiny heads. Abdomen covered with spiny plates. Marine.

Phylum Acanthocephala

The spiny-headed worms. Bodies flat, with spiny proboscis. Parasitic.

Phylum Entoprocta

Bodies have tentacled, cupshaped part attached by stalk to rocks, shells, seaweed, or other animals. Usually marine and colonial.

Phylum Ectoprocta

Resemble entoprocts, except that ectoprocts have a coelum, or a body cavity lined with a membrane.

Phylum Phoronida

Marine worms with long tentacles. Some are hermaphrodites. Live in hard or leathery tubes formed from secretions. Mostly colonial.

Phylum Brachiopoda

The lamp shells. Soft body parts enclosed in bivalve shells. Most attach themselves firmly to rocks or other substrate.

Phylum Mollusca

The mollusks. Body parts usually soft; some enclosed in univalve or bivalve shell. Aquatic or terrestrial. Examples: snail, oyster, octopus.

Phylum Priapulida

Burrowing worms covered with spines. Retractable mouth. Marine.

Phylum Sipuncula

The peanut worms. Burrowing worms with retractable proboscis. Many have tentacles around mouth. Marine.

Phylum Echiura

The spoon worms. Burrowing worms with plump bodies; have proboscis that may extend to several times the body length. Marine.

Phylum Annelida

The segmented worms. Bodies segmented. Aquatic, terrestrial, or parasitic. Examples: earthworm, leech.

Phylum Tardigrada

The water bears. Microscopic. Have four pairs of stumpy legs. Most live in water around mosses or lichens.

Phylum Pentastoma

The tongue worms. Flat body with four claws. Parasites in lungs and nasal passages.

Phylum Onychophora

The velvet worms. Body with 14 to 43 pairs of clawed legs. Terrestrial.

Phylum Arthropoda

The arthropods. Largest animal phylum. Segmented bodies with external skeletons and jointed appendages. Aquatic, terrestrial, or parasitic. Examples: insects, spiders, millipedes, lobsters.

Phylum Pogonophora

The beard worms. Live on sea floor in hard, upright tubes formed from secretions. Long tentacles at front of body.

Phylum Chaetognatha

The arrowworms. Transparent, torpedo-shaped bodies. Marine.

Phylum Echinodermata

The echinoderms. Internal skeleton of calcite crystal plates. Unique circulatory system. Aquatic, mainly marine. Examples: sea urchin, starfish.

Phylum Hemichordata

The hemichordates. Soft-bodied; have gill-slits and proboscis. Marine, some kinds burrowing in sea bottoms. Solitary or in colonies. Example: acorn worm.

Phylum Chordata

The chordates. Large, varied phylum. Have nerve cord; most have bony internal skeleton. Aquatic or terrestrial. Examples: amphioxus, bird, fish, humans.