Comparison to Other Phyla

Phylum	Porifera	Cnidaria	Platyhelminthes	Nematoda
Level of Organization	Cellular	Tissue	Organ System	Organ System
Germ Layers	Absent	Diploblastic	Triploblastic	Three
Symmetry	Asymmetrical	Radial	Bilateral	Bilateral
Cephalization	Absent	Absent	Present	Present
Body Cavity	Absent	Absent	Acoelomate	Pseudocoe- lomate
Segmentation	Absent	Absent	Absent	Absent
Protostome or Deuterostome	------	------	------	------
Digestive System	Intracellular	Gastrovascular Cavity; intracellular	Gastrovascular Cavity	Complete Gut
Circulatory System	Absent	Absent	Absent	Absent
Respiratory System	Absent	Absent	Absent	Absent
Excretory System	Absent	Absent	Flame Cells	Excretory gland cells
Nervous System	Absent	Nerve Net	Head ganglia with longitudial nerve cords	Head ganglia with dorsal and ventral nerve cords
Reproduction	Sexual or Asexual budding)	Sexual or Asexual budding)	Sexual(some hermaphroditic); Asexual(body split)	Sexual(some hermaphroditic)
Support	Endoskeleton of spicules	Hydorstatic Skeleton	Absent	Hydorstatic Skeleton
Habitat	Marine and Freshwater	Marine and Freshwater	Marine, Freshwater, and Terrestrial	Marine, Freshwater, and Terrestrial