The barnacle lives on the loggerhead turtle's body. it does not harm the turtle in any way. the barnacle benefits from the water movement the turtle creates as it swims. the water ripples the barnacle get remnants of food coming out of the turtle's mouth. what is this type of a relationship called?

That is a Symbiotic Relationship, like how birds will clean a crocodile's teeth for them. The birds eat whatever meat is left stuck in its teeth, and the crocodile won't have infections from the stuck meat. Same with water buffalos and birds, the birds get a free meal and the water buffalo don't have ticks and parasites. And another one is a zebra and ostrich, it's a somewhat odd one but still the same. Zebras have poor eyesight while the ostrich has poor hearing. So they travel together so the ostrich can stop the zebra's enemies while the zebra will hear the ostrich's enemy.

The answer is observations and interpreting.