When would you use marine as an object aquatic?

The term "marine" is used as an adjective to describe things related to the sea or ocean, while "aquatic" refers to anything related to water in general, including freshwater environments. You would use "marine" specifically when discussing oceanic contexts, such as marine life or marine ecosystems. In contrast, "aquatic" could apply to both freshwater and saltwater environments, like aquatic plants or aquatic habitats. Therefore, use "marine" when the focus is solely on the ocean and its inhabitants.