Parazoa Animals are eukaryotic, multicellular and heterotrophic Subkingdom Parazoa - Phylum Porifera - includes animals called sponges; simple animals; typically asymmetrical; lack tissue differentiation; lack a true digestive cavity; water enters through several incurrent canals into a central body cavity (spongocoel) and out through a single opening (osculum); lining the spongocoel are special flagellated cells (choanocytes) which phagocytize food particles from water

Cnidaria Phylum Cnidaria includes animals that exist in polyp (attached form) and medusa (freely swimming umbrella-shaped form); mouth is surrounded by tentacles with stinging cells (nematocytes) that are used to catch prey Includes animals whose body is radially symmetrical; have diploblastic (two layered) embryo; sac-like body has a single opening that is used as a mouth and anus Includes animals that are bilaterally symmetrical, have triploblastic (three layered) embryo, and exhibit different levels of cephalization Includes animals that are symmetrical and have tissue differentiation Animals are eukaryotic, multicellular and heterotrophic

Platyhelminthyes Phylum Platyhelminthes includes animals that are non-segmented; have flat, acoelomate body; primitive cephalization; gastrovascular cavity with a single opening; respiratory and circulatory systems are absent; gas exchange directly through the body surface Includes animals that are bilaterally symmetrical, have triploblastic (three layered) embryo, and exhibit different levels of cephalization Includes animals that are symmetrical and have tissue differentiation Animals are eukaryotic, multicellular and heterotrophic

Mollusca Phylum Mollusca includes animals whose soft body is divided into a muscular ventral foot (aids movement), a visceral mass (internal organs), and a mantle (secretes a hard shell) Includes animals that are bilaterally symmetrical, have triploblastic (three layered) embryo, and exhibit different levels of cephalization Includes animals that are symmetrical and have tissue differentiation Animals are eukaryotic, multicellular and heterotrophic

Annelida Phylum Annelida includes animals whose body is divided into structurally similar segments; coelomates (coelomic body cavity lined with mesoderm); small brain connected to ventral nerve cord Includes animals that are bilaterally symmetrical, have triploblastic (three layered) embryo, and exhibit different levels of cephalization Includes animals that are symmetrical and have tissue differentiation Animals are eukaryotic, multicellular and heterotrophic

Nematoda Phylum Nematoda includes animals that have cylindrical body with tapering ends; thick cuticle covers their body surface; pseudocoelomates (have a coelom that is only partially covered by mesoderm) Includes animals that are bilaterally symmetrical, have triploblastic (three layered) embryo, and exhibit different levels of cephalization Includes animals that are symmetrical and have tissue differentiation Animals are eukaryotic, multicellular and heterotrophic

Arthropoda Phylum Arthropoda includes animals whose body is divided into segments (head, thorax, abdomen); body covered by exoskeleton; have paired appendages; have open circulatory system that has a heart that pumps hemolymph into body cavities to exchange gases with a tracheal system Includes animals that are bilaterally symmetrical, have triploblastic (three layered) embryo, and exhibit different levels of cephalization Includes animals that are symmetrical and have tissue differentiation Animals are eukaryotic, multicellular and heterotrophic

Echinodermata Phylum Echinodermata includes animals that are actually radially symmetrical but are included in branch bilatria because of triploblastic embryo development and presence of body systems; calcareous endoskeleton is located just under a bumpy skin; small tube feet on the under surface for movement and gas exchange Includes animals that are bilaterally symmetrical, have triploblastic (three layered) embryo, and exhibit different levels of cephalization Includes animals that are symmetrical and have tissue differentiation Animals are eukaryotic, multicellular and heterotrophic