Ecological relationship is the relationship between an organism in its ecosystem. All organisms in an ecosystem are connected in one way or another. Each interaction depends on the one before it.
Commensalism - Barnacles and whales
Barnacles are arthropods contained in the class Crustacea along with lobster’s crabs and shrimp. They're believed to be one of the oldest surviving animals on Earth. There are more than 1,000 species of barnacles inhabiting brackish and saltwater environments worldwide. Although some barnacles are parasites most are filter feeders.
Filter-feeding barnacles are