What are the first level consumers in an ocean?

some fish, whales, dolphins sharks?

Sharks, dolphins, and whales are a fewyou are wrong shark is a third level consumer

small fish, shrimp and Sheldon plankton

Yes,second level consumers can be first level consumers due to the fact that most second level consumers eat producers like berries,plants etc.

Grass can be a first-level consumer and a second-level consumer.