The decline of dinosaurs led to the evolution of a new marine order known as cetaceans. Today's species of whales and dolphins began to emerge 10 million years ago. Among these 86 species that exist today, whales constitute the majority of Odonotocetes and Mysticetes. These creatures are among the largest in the world and exhibit an equally unique way of communicating with each other. Baleen and toothed whales communicate using sounds, but neither has an external ear. Sounds are detected through a fatty structure between the middle ear and the mandible, while the sounds made to communicate vary between species or, in the case of an orca, between pods. Mysticetes do not contain vocal cords, but vocal cords with which they communicate and generate some of the most resounding biological sounds known to man. These series of clicks and moans come together like a whale song and are used to communicate everything from possible threats to identifying another whale to mating calls. Odonotocetes communicate a little differently by making high-pitched sounds and echoes to move around and determine the location of objects. Echolocation is imperative and provides a three-dimensional view of the underground world where only 1% of sunlight travels up to 100 meters deep. Migratory whales communicate using these methods over vast distances, such as 4,500 kilometers, and continue to make the same sounds with each other. Even when slight changes between clans occur seasonally, the rest of the members of other breeding grounds follow suit. In 1996, when two humpback whales ventured from the Indian Ocean to the Pacific Ocean with their own unique song, it was just... middle of paper...... pollution. Natural causes include avoidance of predators or weather conditions as well as the possibility of hunting prey or the unfortunate illness of a whale in the group. Pilot whales are often victims of mass strandings for several reasons. They are very social creatures, so if one member of the group becomes ill and ventures ashore, the other will follow. This can be seen when recently in Florida about 50 pilot whales were stranded, starting with a small number and steadily increasing as they communicate with each other ( ). It is natural for one whale in a group of pilot whales to follow another to shore, since these creatures are gregarious; however, the fact that these are deep-sea whales emerging from great depths to beach themselves is not a common feat. However, scientists are discovering that it actually plays a major role.