The sperm whale (Physeter macrocephalus) is the largest toothed predator on Earth, drawing focus to its remarkable dental structure. These massive marine mammals possess large, heavy, conical teeth found almost exclusively in the animal’s long, narrow lower jaw. This specialized dentition is a defining characteristic of the species, yet their precise function has long been a subject of scientific inquiry.
Physical Structure and Anatomy
Sperm whale teeth are substantial, reaching up to 8 inches (20 centimeters) in length and weighing over two pounds each. A mature whale typically has 18 to 26 pairs of these teeth, totaling 36 to 50, all situated along the lower jaw. They are composed primarily of dense dentin, covered by a layer of cementum, which gives them the ivory-like quality that made them historically sought after.
Unlike the teeth of many other mammals, sperm whale teeth lack a thick layer of enamel. The conical lower teeth fit neatly into corresponding sockets or depressions found in the gum line of the upper jaw. The upper jaw contains only a variable number of vestigial, or rudimentary, teeth that rarely erupt above the gum line. This anatomical arrangement means the sperm whale’s mouth lacks a true interlocking set of teeth, raising questions about their primary biological purpose.
Role in Predation and Feeding
The most striking aspect of the sperm whale’s teeth is that they do not appear strictly necessary for capturing prey. Sperm whales are deep divers that feed mainly on large, slippery cephalopods, including giant squid. Evidence suggests that many well-fed individuals have been found with broken jaws or teeth that are severely worn down or missing, indicating that dentition is not the sole means of securing food.
The prevailing theory suggests the whale uses powerful suction to draw prey into its mouth, a method highly effective for capturing soft-bodied creatures in the dark depths. The lower teeth may function to grip the prey, particularly larger or more active species, long enough for the whale to maneuver the meal for swallowing whole. The teeth fitting into the upper jaw sockets may also help create the necessary seal for generating suction force.
Beyond feeding, the teeth are implicated in the social behavior of the species. Mature male sperm whales often display extensive linear scars on their heads and bodies, known as “rake marks,” inflicted by the teeth of other males. This suggests the teeth are frequently employed during aggressive, intraspecies interactions, likely related to establishing dominance hierarchies or competing for mating access. The teeth may function more as weapons for ritualized combat than as tools for daily foraging.
Historical and Artistic Uses
The physical characteristics that make sperm whale teeth unique also made them highly valuable to humans. The dense, ivory-like material provided a durable medium for artistic expression, particularly during the 19th-century whaling era. Whalers developed scrimshaw, etching detailed images into the polished surface of the teeth and then rubbing pigment into the incisions to make the designs visible.
Scrimshaw pieces often depicted scenes from maritime life, portraits, or elaborate geometric patterns, transitioning the biological artifact into a cultural object. These engraved teeth were frequently exchanged, sold, or given as gifts. The teeth also held profound significance in certain Oceanic cultures, notably in Fiji, where they are known as Tabua.
Tabua were traditionally prepared by polishing the teeth and sometimes smoking them to achieve a dark, tobacco-like color. These objects functioned as a form of ceremonial currency reserved for solemn social and political occasions. They were presented at important events, such as weddings, funerals, or to solidify an agreement. The exchange of Tabua carried significant spiritual and social weight, underscoring the deep cultural value placed on this unique part of the sperm whale.