[Hearing mechanisms in dolphins and baleen whales (author's transl)]

Dolphins have the most highly developed acoustical system in nature. They are not only able to hear far into the realm of ultrasound, but they have also developed a magnificent echolocation system. Baleen whales, on the other hand, are specialists for extremely low frequencies, without echolocation. In order to overcome technical problems it was necessary to drastically alter the construction of the hearing organ, of the entire skull, and even the skin. A short review of the current knowledge is presented, along with a discussion of the biotechnology involved.