Symbiosis that is beneficial to both organisms involved.

Clownfish and sea anemones: Clownfish are small, brightly-colored fish found in coral reefs. They are frequently found in the tentacles of sea anemones, which typically capture their prey by paralyzing them with discharged cnidoblasts (nematocysts), and then ingesting the animal within the gastrovascular cavity. Studies have shown that a component of clownfish mucus inhibits the discharge of these cnidoblasts. Clownfish and sea anemones present an example of facultative mutualism. The clownfish benefits by having a protected home territory. What does the sea anemone gain from this arrangement? ExamplesOfMutualism.htm

An association between two organisms in which one benefits and the other derives neither benefit nor harm.

Barnacles adhering to the skin of a whale or shell of a mollusk: Barnacles are crustaceans whose adults are sedentary. The motile larvae find a suitable surface and then undergo a metamorphosis to the sedentary form. The barnacle benefits by finding a habitat where nutrients are available. (In the case of lodging on the living organism, the barnacle is transported to new sources of food.) The presence of barnacle populations does not appear to hamper or enhance the survival of the animals carrying them fCommensalism.htm

the relation between two different kinds of organisms in which one receives benefits from the other by causing damage to it definiton

Giardia lamblia: Metabolically active trophozoites reside in the small intestine du/~seisen/Exam plesOfParasitism. htm

Brood parasitism of robin nest - robin feeds a cuckoo chick