Whales are the largest creatures on earth. The blue whale, the largest whale, is actually the largest organism in the history of the world. These gigantic animals are actually aquatic mammals, which means they are more closely related to us humans than they are to other fish. The dark, watery abode of these animals largely negates the senses of sight and smell. However, sound travels faster in water than in air. Thus, many aquatic species have developed the use of echolocation techniques. Whales and dolphins make extensive use of this technique. Whales also use various gestures to communicate with each other. Sounds primarily serve as sonar in toothed whales, and mating calls in baleen whales. Whales have honed the technique of echolocation and communication through sound over millions of years of evolution. They are so proficient at it that scientists have observed various 'dialects' of whale vocalizations in different groups! Two types of vocalization is observed in whales. Odontoceti, the toothed whales, do not produce 'whale songs', and converse in short 'clicks' and whistles. Isolated clicks are used for echolocation, while clicks and whistles are grouped together for communicative purposes. The toothless baleen whales generate and are known for the popular whale songs. The mechanism in the two differs slightly. Odontoceti, called toothed whales, are a suborder of cetaceans, including toothed whales, such as the sperm whale, as well as dolphins and porpoises. This creates problems in discussions about whales and other cetaceans, since conventionally named 'whales', such as sperm whales and bottlenose whales, are included in the group whales, whereas dolphins and porpoises are excluded and treated as a separate class of organisms. Odontocetes produce sounds via an organ similar to the nose in humans. Thus, the process can be anatomically likened to humming. Odontocetes have a physical structure, anatomically comparable to the nasal cavity in humans, called phonic lips. When air is passed through the phonic lips, the area around the lips vibrates, creating finely adjustable sounds. These sounds are then transferred to a fatty organ in the forehead called the melon, which directs the sound in the intended direction. Pods of dolphins are often very 'chatty'. Researchers have noted that dolphin sounds are distinctly distinguishable from each other, but since their meaning is hard to decipher, pods of dolphins often sound like children's chatter on a playground! These huge animals are known for their elaborate communicative and mating calls, known as 'whale songs'. The sound-producing mechanism in baleen whales is not yet clear, although it is believed that, like humans, their larynx is responsible for creating the sounds. But since whales don't have vocal cords and don't exhale while producing sound, this analogy is not completely accurate. Whales are thought to be capable of recycling the air used in sound production. Baleen whales do use echolocation, but not as extensively as toothed whales. Since their sense of smell is also not as well-developed as predators like sharks, scientists are unclear how baleen whales navigate so accurately on a regular basis. Some scientists claim that increasing human activity in the oceans is hindering whale communication. Since whales rely extensively on sounds as a mode of communication, these ambient noises are quite harmful to their feeding, navigation, and ultimately survival. Whales also communicate through several gestures, although this is not their primary mode of communication. Slapping the water with the tail is used to display aggression, and to warn off potential competitors. It is also a tool to scare and herd prey together, making them easier to pick off. Similarly, breaching -- jumping out of the water -- is a display of aggression. Due to whales' massive size, breaching never goes unnoticed. The world was utterly amazed by whale songs when the behavior first came to light, and some scientists are now even working towards finding if these magnificent creatures have a 'language' of their own.