Buoyancy control as a function of the spermaceti organ in the sperm whale

Abstract

Factors influencing buoyancy of the sperm whale throughout its geographical and depth ranges are discussed and the effects of variation in sea-water density, the volume of air in its lungs and the effect of pressure on its tissues are analysed. It is shown that by dropping the temperature of spermaceti oil in its head by about 3 °C the whale could make itself neutrally buoyant at its operational depths deeper than 200 m over its whole geographical range. It is shown that sufficient heat could be lost in the time available and alternative mechanisms for this are described and discussed. Sufficient heat is available to the whale in a diving cycle for re-heating the oil. This hypothesis of buoyancy control accounts for many of the unusual features of the sperm whale such as general and detailed structure of the snout, thermal properties of the spermaceti oil, the volumes and dimensions of the oil and nares, the whale's buoyancy at the sea surface and the temperature of the oil when at the sea surface. © 1978, Marine Biological Association of the United Kingdom. All rights reserved.