They have an open circulatory system.
	They are segmented animals.
	They have no true tissues.
	Food is digested within a gastrovascular cavity.
	They are pseudocoelomates.

	They have three tissue layers (they are triploblastic)
	They respire via book lungs.
	They have a nerve net.
	They are segmented.
	They have an exoskeleton composed of chitin.

	Cnidaria
	Arthropoda
	Platyhelminthes
	Chordata
	Nematoda

	They lack a nervous system.
	They lack a body cavity.
	They have a digestive system with two openings.
	Their body plan has two main tissue layers.
	They are segmented.

	flatworms
	arthropods
	rotifers
	annelids
	chordates

	Nematoda
	Annelida
	Chordata
	Platyhelminthes
	Arthropoda

	They lack an excretory system.
	They have a body cavity.
	They have a bony endoskeleton.
	Their digestive system consists of a gastrovascular cavity.
	Their body plan consists of two tissue layers.

	Chordata
	Mollusca
	Cnidaria
	Arthropoda
	Echinodermata

	a closed circulatory system
	segmentation
	two tissue layers
	an alimentary system with two openings
	an exoskeleton

	their skin
	nephridia
	book lungs
	spiracles and tracheae
	Malpighian tubules

	Annelida
	Mollusca
	Nematoda
	Arthropoda
	Echinodermata

	exhibit bilateral symmetry
	exhibit radial symmetry
	are asymmetrical
	exhibit no symmetry
	lack a digestive system

	a closed circulatory system
	nephridia
	a brain
	two tissue layers
	tube feet

	an endoskeleton
	a closed circulatory system
	no excretory system
	a brain
	lungs

	Echinodermata
	Cnidaria
	Arthropoda
	Mollusca
	Chordata