Cnidaria, one of the seven phylums, consists of jellyfish, anemones, corals, and hydroids. The name Cnidarian originates from the greek word "cnidos" which means stinging nettle. They are all radially symmetrical meaning that they all are centered around an axis and contain nematocysts which is a venom allowing them to consume their prey more easily. Cnidarians eat plankton, algae, and little fish and live primarily in salt water.