The clownfish, or anemone fish, performs an dance with the anemone before taking up residence: it touches the anemone's tentacles with different parts of its body until it is acclimated to their host. A layer of mucus on the clownfish's skin makes it immune to the fish-eating anemone's lethal sting. In exchange for safety from predators and food scraps, the clownfish drives off intruders and cleans its host, removing parasites that might attack. What type of relationship exists between the clownfish and the anemone?