The decline of the dinosaurs led to the evolution of a new marine order known as the Cetacea. Current species of whales and dolphins began to emerge 10 million years ago. Of these 86 species that exist today, whales make up the majority of both Odonotocetes and Mysticetes. These creatures are among the largest in the world and display an equally unique way of communicating with each other. Both baleen whales and toothed whales communicate using sounds, but neither has an external ear. Sounds are detected through a fatty structure found between the middle ear and jaw, 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 instead have vocal cords with which they communicate and generate some of the most resonant biological sounds known to man. These series of clicks and moans come together like whale songs and are used to communicate everything from possible threats to identifying another whale to mating calls. Odonotocetes communicate slightly differently by making high-pitched sounds and echoes to orient themselves and determine the location of objects. Echolocation is learning and provides a three-dimensional view of the world below where only 1% of sunlight travels down to 100 meters deep. Migrating whales communicate through these methods over large distances such as 4,500 kilometers and continue to produce the same sounds with each other. Even when small changes between clans occur seasonally, the rest of the members in other breeding grounds follow suit. In 1996, when two humpback whales ventured from the Indian Ocean to the Pacific Ocean with their unique song, it was just… middle of paper… pollution. Natural causes include avoidance of predators or weather conditions, as well as the opportunity to chase prey or the unfortunate illness of a whale in the pod. Pilot whales are often victims of mass strandings for a variety of reasons. They are very social creatures, so if one member of the pack gets sick and ventures ashore, the other will follow. This can be seen recently, in Florida, about 50 pilot whales were stranded, starting from a low number and steadily increasing with the squawks communicating with each other ( ). It is natural for one whale in a pod of pilot whales to follow another to the shore, being such gregarious creatures; however, the fact that these are deep-sea whales emerging from great depths to beach themselves is not a common feat. however scientists are finding that it actually plays an important role.