Where do Cnidarians live?

Cnidarians such as sea anemones primarily live in great coral reefs, near the shoreline in shallow water. Jellyfish of the Cnidarian phylum can be found in extreme depths and shallow tide pools, and some Cnidarians can survive in freshwater too.

The (typical) Cnidarian life cycle:

A hydrozoan Cnidarian, such as a Moon Jelly, starts as a fertilized egg. As a planula, or larva, it swims around and eventually plants itself on a study surface. It reaches the polyp stage and buds off of itself. Then the polyp turns into a strobola and branches out, turning eventually into an ephyra, which is a smaller and lighter version of the actual medusa. As an adult medusa, it can lay eggs and start the whole process over again.

Life cycle of a Moon Jelly Game:

http://www.neaq.org/education_and_activities/games_and_activities/online_games/jellies_game.php

How do Cnidarians reproduce?

Some Cnidarians reproduce sexually, but others are able to be female and male at the same time, so they reproduce asexally.

Can Cnidarians communicate with each other? How do they do it?

Some jellyfish of the Cnidarian phylum can communicate by different flashing lights in their bodies. Still others can release certain chemicals into the water that others of their species can pick up.

How do Cnidarians move?

By a type of jet propulsion; they suck water into their mouths and spit it out in a powerful burst.

How do Cnidarians espond to stimuli?

Cnidarians have sensitive nervous tissue that allows rapid communication between cells, enabling coordinated movement.

How do Cnidarians breathe?

Cnidarians use diffusion for respiration, excretion, and circulation.