Life on the Move


Level of Organization

Cnidarians achieve a tissue organization, but organs are not present. Specialized cells group together to create tissues.

Germ Layers

Cnidarians have 2 germ layers: Ectoderm and Endoderm layers


Cniadarians have radical symmetry. They radiate from the center and if divided down the central axis, they will be symmetrical.


Cnidarians do not have cephalization.

Body Cavity

They lack a body cavity, but do have a gastrovascular cavity which helps them digest food. This is one big area in the Cnidarian.


Cnidarians do not have segmentation

Digestive System

Their tentacles inject prey with toxins and ener the prey through the mouth into the gastrovascular cavity. Nutrients is stored in the food vacuoles.

Ciculatory System

They do not have/need a circulatory sytem because they obsorb oxygen through their thin bodies.

Respiratory System

They do not have a respiratory system. They get oxygen through the water which is filtered through their thin bodies. Their body can diffuse water in and out of it.

Excretory System

They consume food and get rid of waste through the same spot.

Nervous System

Cnidarians have a nerve net which is not centralized and is only associated with simple sensory structures. They can detect and respond to stimuli in all directions.


Cnidarians have both asexual and sexual reproduction. The two stages alternate and one produces the other.


Cnidarians have a hydrostatic "skeleton." Meslogea is the endoskeleton and chitin is their exoskeleton.