2. Dugong: Dugong has the title of "mermaid", which is very similar to manatees and is currently mainly distributed in tropical waters. Dugong's movements are very slow, and the requirements for water quality are very high.
3. Bluefin tuna: Bluefin tuna is mainly distributed in the Pacific Ocean and the Atlantic Ocean, with different habitats and likes to move in groups.
4. Blue whale: The blue whale is the largest creature in the world at present. Its daily food intake can reach more than 4 tons, and the heaviest can reach more than 200 tons.
5. Tortoise shell: Tortoise shell belongs to a kind of sea turtle, with a large body, averaging over 1.6 meters, and scales distributed on the forehead.