Have stinging cells (a must to be a cnidarian) to capture preyHave radial symmetryCentral pointSoft Corals, Hard Corals, Sea Fans, Hydra, Jellyfish, Sea Anemones

Create coral reefs at growths of inch per yearDeposit skeleton of calcium carbonate (limestone)Photosynthetic and symbiotic dinoflagellates (zooxanthellae) live within coral structure and provide energy to growing coral.

Toxins in nematocysts are quite potentOf the 9,000 to 10,000 cnidarians, only a handful pose a threat to humansIn most cases, nematocysts are not strong enough to penetrate skin

Organ Pipe Coral

Sea Surface Temperature Changes

StomachMouth

Distinct floats that allow wind to push them through the water

Sting can be life threatening

Tentacles exceed 40 meters (131 ft) in length

Lives in tentacles of Man-of-War jellyfish much like a clownfish lives in an anemone

Immune to sting

Use jellyfish for protection in open ocean

Most dangerous to humansPotent toxin can kill an adult human within minutesCause paralysis and lyse blood cellsFortunately, rare in most parts of world