Plylum

Porifera

No Symmetry (asymmetrical)

No germ layers

No Coelom (no body cavity) |

Made of spicules (calcium deposits)

Water enters through Ostium, exits via Osculum (channels) |

Choanocytes filter/eat food

Has no tissues

Cnidaria

First signs of specialized tissues

Radial symmetry

Diplobastic (no mesoderm/middle layer)

Mouth opening dual function (ingestion/excretion)

Can't use A/pseudo eucoelomate (Can only be used when discussing triplobasts)

Two body forms: Polyp (sessile) and Medusa (mobile)

No organs (no respiratory/circulatory system) |

Gastrovascular system present (gas exchange)

Mollusca

Bilateral symmetry

Inploblastic (three germ layers)

Coelom present

Complete digestion system - separate openings for mouth and anus

Protostones

Muscular foot for movement

Visceral mass contains organs for digestive, excretory and reproductive systems

Shell is a protective layer (internal or external)

Most classes have open circulatory system

Platyhelminthes

Bilateral symmetry

Triploblastic (three germ layers, but aceoelomate, not pseudo)

Soft-bodied

One opening for food/waste

Flattened body great for diffusion (respiration)

Gastrovascular system present

Cephalized with longitudinal nerve cords (transverse branches)

Annelida

Bilateral symmetry

Triploblastic

Coelom (gut and otber organs are suspended in fhud-filled cavity)

Separate entry/exit points for food/waste (Protostone)

Sexual reproductive organ closer to mouth (epidermal layer)

Closed circulatory system

Segmented body (each having its own muscle/bervous tissue)

Gills for gas exchange

Nematoda

Bilateral symmetry

Pseudocoelom (not a true coelom, refer to distinction at end of page) |

Triploblastic

Nervous system similar to Platyhelminthes, but with more ganglion bodies

No segmentation

Complete digestive tract (two points)

No circulatory/respiratory system (gas exchange - diffusion dependent)

Echinodermata

Radial symmetry

Triploblastic Deuterostome Endoskeleton

No heart (open circulatory system)

Central nerve ring with radial nerves

Arthropoda

Bilateral symmetry

Exoskeleton

Protostome

Coelom present (complete digestive system)

Mouth configuration varies with class

Dorsal brain/ventral nerve cord

Chordata

Bilateral symmetry

Coelom present

Triploblastic

Deuterostome (mouth develops second)

Four common characteristics: dorsal hollow nerve cord, notochord, gill slits, post-anal tail Introduction to vertebrates (see additional information)