The classification of sea lions, dolphins and turtles into one category and sea stars, jellyfish and anemones into one category is based on
Whether it is a mammal. Sea lions, dolphins and sea turtles are all mammals, but starfish, jellyfish and anemones are not mammals, so sea lions, dolphins and sea turtles are classified as one class, and starfish jellyfish anemones are classified as one class. Mammals are animals with the highest morphological structure and the most perfect physiological functions in the animal world.