What are the three types of sea creatures called?

Sea creatures are commonly categorized into three types: fish, invertebrates, and marine mammals. Fish are aquatic animals with gills and fins, such as salmon and tuna. Invertebrates include creatures like jellyfish, octopuses, and crustaceans, which lack a backbone. Marine mammals, such as dolphins and whales, are warm-blooded and breathe air, distinguishing them from other sea life.