Sonar waves bounce off the bottom of the ocean. Oil spill sare harmful to animals and the enviroment. Dolphins talk and communicate to each other by clicks or whistles. The largest oil spill ever happened in Alaska. Countershading is only found on ocean animals.
Whales are almost extinct.
Sharks live only in warm water. Fish eat only plankton. Frogs live in oceans. Tidal power plants are expensive. The Indian Ocean the largest ocean in the world.