Located worldwide in deep and coastal waters
A type of Nematocyst
Often attached to coral or rock
Appearance consists of a single polyp with a cylindrical body
Their mouths are surrounded by cnidocyte-containing tentacles
Cnidocytes are cells containing one giant secretory organelle called a cnidocyst that can deliver a sting to other organisms
Cnidocytes are cells containing one giant secretory organelle called a cnidocyst that can deliver a sting to other organisms<unk>  venom contains multiple enzymes including:
Cytolytic/hemolytic toxins
Neurotoxins
Cardiotoxins
Protease inhibitors
Cytolytic/hemolytic toxins
Neurotoxins
Cardiotoxins
Protease inhibitors
Physical contact or osmotic gradient  causes discharge of nematocysts
A spring loaded venom delivery system
Once opened, a nematocyst releases all of its contained venom
Sea anemone envenomation
Toxins
Fire coral envenomation
Ciguatera
Box jellyfish envenomation
Scombroid
Crown-of-Thorns starfish envenomation
Tetrodotoxin 