Sponges

 phylum Porifera (por IHF er uh), "pore bearers"

they have tiny openings, or pores, all over their

bodies .

Sponges

 are classified as animals because they are

multicellular, heterotrophic, lack cell walls, and

contain a few specialized cells.

Sponges are the most ancient members of the kingdom Animalia; the simplest multicellular organisms

Cnidarians

Jellyfishes, sea fans, sea anemones, hydras

and corals 

Cnidarians

are aquatic, soft-bodied, carnivorous,

radially symmetrical animals with stinging tentacles

arranged in circles around their mouths. Some, such

as corals, have skeletons. They are the simplest

animals to have body symmetry and specialized tissues. Some cnidarians live as independent individuals.

Others live in colonies composed of many

individuals.

Arthropods

include spiders; centipedes; insects; and

crustaceans, such as crabs. Arthron means

«joint" in Greek, and

podos means "foot."

Arthropods

 have bodies divided into segments,

tough external skeleton called an exoskeleton,

cephalization, and jointed appendages.
Most number of species.

Nematodes

(Roundworms)

unsegmented worms with pseudocoeloms, specialized tissues and organ systems, and digestive tracts with two openings-

a mouth and an anus. Some are free-living

and inhabit soil or various aquatic habitats. Others

are parasites that infect a wide range of plants and

animals, including humans.

flatworms

Platyhelminthes

(plat ih h el MIN theez

Flatworms are soft, unsegmented, flattened worms

that have tissues and internal organ systems. They

are the simplest animals to have three embryonic

germ layers, bilateral symmetry, and cephalization.

Most flatworms are no more than a few millimeters

thick. Flatworms do not have coeloms.

Annelids

The phylum Annelida

(un NEL ih duh)

includes earthworms,

some exotic-looking

marine worms, and

parasitic, bloodsucking

leeches.

Annelids

worms with segmented bodies and a

true coelom lined with tissue derived from mesoderm.

Mollusks

The phylum Mollusca

includes snails, slugs,

clams, squids, and

octopi.

Mollusks.

 soft-bodied animals that typically have

an internal or external shell. Like annelids, mollusks

have true coeloms surrounded by mesoderm. They

also have complex organ systems.

Echinoderms

includes sea stars, sea urchins, and

sand dollars, all of which live only in the

sea.

Echinoderms

have spiny skin and an internal skeleton. They also have a water vascular systema

network of water-fill ed tubes that include suction-cuplike structures called tube feet, which are used for walking and for gripping prey. Most adult

echinoderms exhibit five-part radial symmetry. The skin of an echinoderm is stretched over an internal  skeleton of calcium carbonate plates. Although radial

symmetry is characteristic of simpler animals such

as cnidarians, echinoderms are more closely related

to humans and other chordates because they are

deuterostomes.