The sperm whale’s distinctive name comes from a unique biological feature: a specific substance found within its massive head. This article explores the nature of this substance, the organ that produces it, and its historical significance, all contributing to the whale’s enduring name.
The Spermaceti Substance
The term “sperm” in sperm whale refers to spermaceti, a waxy, oily substance found within the whale’s head. When extracted, this substance appears as a whitish, semi-liquid material. Early whalers mistakenly associated its appearance with seminal fluid, leading to the name “spermaceti,” which means “whale sperm” in Medieval Latin. This misconception became the established term for the substance and the whale.
Chemically, spermaceti is primarily composed of wax esters, notably cetyl palmitate, which can constitute up to 70% of its composition. At the whale’s body temperature, this substance is a clear, fluid oil. Upon cooling to around 30°C to 50°C, it solidifies into a white, crystalline wax that is hard yet oily to the touch.
The Spermaceti Organ
The spermaceti substance is housed within a massive anatomical structure in the whale’s head known as the spermaceti organ. This organ can occupy up to 40% of the whale’s entire length, containing as much as 2,000 liters (approximately 500 gallons) of spermaceti. It is located above the upper jaw, composed of a large, barrel-shaped “case” filled with the waxy fluid, and a lower part called the “junk” with spermaceti-filled compartments separated by cartilage.
Scientists propose two biological functions for this organ. One theory suggests it plays a role in buoyancy control, allowing the whale to adjust its density for deep dives by manipulating the spermaceti’s temperature. Cooling the spermaceti increases its density for descent, while warming it decreases density for surfacing. Another theory is its role in echolocation, functioning as an acoustic lens to focus and direct the clicking sounds the whale uses to navigate and hunt. The spermaceti’s acoustic properties, including its high sound transmission speed, are well-suited for this purpose.
Historical Value of Spermaceti
Spermaceti’s economic importance during the whaling era contributed to the “sperm whale” name. This substance was valued for its properties, which surpassed those of conventional whale oil. Spermaceti was a superior illuminant, producing a bright, clean, and odorless flame in lamps. This made spermaceti lamps desirable compared to lamps burning other oils that produced smoke and unpleasant odors.
Its use in candle making was notable, as spermaceti candles burned cleanly and without odor, providing a consistent light source. The “candlepower,” a former unit of luminous intensity, was defined based on the light produced by a pure spermaceti candle.
Beyond illumination, spermaceti found applications as a high-quality lubricant for delicate machinery due to its low viscosity and stability. It was also used in cosmetics, ointments, pharmaceuticals, leatherworking, and textile finishing. These valuable uses made the spermaceti substance, and the whales that yielded it, economically significant, solidifying the name “sperm whale.”