What is the symbiotic relationship between the cleaner fish and shark?

Sharks do not have a symbiotic relationship with the fish they eat. However, a lot of sharks do have a symbiotic relationship with remoras. This small, tubelike fish attaches itself to larger fish (including sharks) by means of a suction cup on its head. It eats external parasites off the shark. The remora gets a free meal and the shark gets rid of its parasites.