Main Characteristics of Cnidarians

There are 11,000 species of cnidarians.
They are divided into five classes: anthozoa, stalked jellyfish, box jellyfish, true jellyfish and hydrozoans.
Anthozoa are attached to the sea bed. They include corals and sea anemones.
The box jellyfish include the particularly poisonous sea wasp.
Well-known true jellyfish are the moon jellyfish and the fried egg jellyfish. The Portuguese man o' war is one of the hydrozoans.
Cnidarians are poisonous and cause painful wounds when touched.
They live in salt water, some also in fresh water. Most are carnivores.

Cnidarian Family Tree