The Sociology Of Dolphins

Dolphins are believed to imitate human speech by means of echolocation. (Encyclopedia Americana 262). Echolocation is emittance of sounds in the form of short pulses, called clicks, and listening for return echoes. (Carwardine 131). The process of echolocation is believed to work like this: Sound is produced internally. The “brain” focuses this sound into a beam. Reflected echoes carrying information about targets are received at the “acoustic window” area of the dolphins’ lower jaw. The sound is then transmitted by the fatty organ in the lower jaw to the middle ear and then to the brain for processing and interpretation. (Carwardine 133)

In spotted dolphins, each one is believed to have its own identification signal, or a “signature whistle.” (Cox 123)

Dolphins have few predators other than man. Sharks, killer whales, and false killer whales have been seen as threats to dolphins, as scars are commonly found on dolphins. However dolphins and toothed whales often “rake” each other with their teeth in competition for females and to show dominance. This can be a cause of scarring. (Donoghue and Wheeler 39).

In conclusion, the dolphin is a complex animal that exhibits many social behaviors. These are shown in the way it communicates with other dolphins through echolocation, the way it expresses sexual interest, the way it feeds on schools of fish and through some of its extraordinary senses.

Sound travels about five times as fast in water as it does in air, because water is much denser than air. The density difference between the two makes it difficult for sound to pass between the two media. This is called an “acoustic impedance mismatch” between the two media. (Carwardine 130). Because of this imbalance, an air-filled ear is useless to the dolphins. That is why the have no external ears. They have tiny ears located behind the eye and are indicated by a small hole. In the bottlenose, this hole is about five to six centimeters behind the eye, and only about two to three centimeters in diameter. (Carwardine 131).

Adults of the bottlenose dolphin reach sexual maturity after 5 to 12 years in females and 9 to 13 years in males. They mate in the spring. After a gestation period of 11 or 12 months, a single calf is born, tail first. Calves swim and breathe minutes after birth; they nurse for up to 18 months. They are able to keep up with the mother by remaining close and taking advantage of the aerodynamic effects of the mother's swimming. (Encarta Online)

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