By: Paige Barnett

Level Of Organization

They have an organ level of organization

Germ Layers

They have three germ layers. They are the ectoderm, mesoderm, and endoderm.


They have bilateral symmetry.


It does not show this.

Body Cavity

They have an internal body cavity.


They are unsegmented.

Digestive System

They have a definite digestive system that runs the length of their bodies. It has a mouth, pharynx, intestine and anus.

Circulatory System

They don't have one so they use diffusion to circulate substances.

Respiratory System

They don't have a formal respiratory system. They breathe through diffusion.

Excretory System

They have an anus near it's rear end and a series of excretory tubes that end in an excretory pore.

Nervous System

They have two nerve cords that transmit impulses through it.


They reproduce sexually. When it is time to reproduce, the sperm cells pass through the spicule. Over 200,000 eggs can be deposited at once in the soil once they are fertilized.


They do not have a skeleton.