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The sea cucumber has a very unusual defense mechanism. Many species use the Cuvierian tubules, which are located in the digestive system of the animal to confuse would be predators.  When stimulated, they will raise their anus, point it in the direction of the stimulation, and contract the body wall to expel the tubules through the anal opening. The Cuvierian tubules are sticky and toxic, and are used to simply confuse the predator. These digestive tubules are lost when the sea cucumber takes this action, and can be re-grown later.