The sperm whale, or cachalot, is the planet’s largest toothed predator, a fact that has made it a figure of fascination for centuries. These giants of the deep ocean navigate dark waters to hunt, evoking a sense of power and mystery. Their immense size and unique physical traits have also made them subjects of scientific curiosity and legends in maritime lore.
The Unique Dental Anatomy of Sperm Whales
A primary feature of a sperm whale’s mouth is its long, narrow, and underslung lower jaw. This mandible houses all the animal’s functional teeth, typically numbering between 18 and 26 on each side. Each conical tooth can reach up to 20 centimeters in length and weigh over a kilogram, and is composed primarily of dentin and cementum, lacking the enamel that covers the teeth of many other mammals.
This dental arrangement is highly specialized. The upper jaw, in contrast to the lower, lacks any erupted teeth. Instead, it contains a series of sockets that correspond to the teeth in the mandible below. When the whale closes its mouth, the lower teeth fit snugly into these upper jaw depressions.
The teeth grow in layers as the whale ages, a feature scientists can use to determine the approximate age of an individual. Sperm whales are monophyodonts, meaning they only grow one set of teeth for their entire lives. The two sides of the lower jaw are fused for most of their length, giving the mandible a distinct, rod-like shape that supports this dentition.
How Sperm Whales Use Their Teeth
A common misconception is that sperm whales use their large teeth to chew food. In reality, these whales swallow their prey, such as colossal and giant squid, whole. The purpose of their teeth is still a subject of scientific discussion, as healthy, well-fed whales have been observed with missing or damaged teeth, indicating they are not strictly necessary for feeding.
One theory suggests the teeth are used for social and competitive interactions. Mature males often bear scars on their heads and bodies inflicted by the teeth of other males, which points to their use in aggressive encounters during battles over potential mates or territory.
Another hypothesis is that the teeth aid in capturing large, slippery prey. While not used for chewing, the conical teeth could help grip and secure struggling animals like squid, preventing their escape before being swallowed. The way the lower teeth lock into the upper jaw might also help create a seal to suck prey into their mouths, suggesting their function is likely multifaceted.
Whale Teeth in Human Culture
The teeth of the sperm whale have held a significant place in human history, particularly within maritime cultures. For 19th-century whalers on long voyages, these teeth became the medium for a folk art known as scrimshaw. Sailors would spend idle hours polishing the ivory-like teeth and engraving intricate designs onto their surfaces. Common motifs included whaling scenes, nautical symbols, ships, and portraits of loved ones.
This art form transformed a byproduct of a dangerous industry into artifacts and personal mementos. Scrimshaw required patience and skill, with whalemen using simple tools like pocketknives or needles to etch their illustrations. The engraved lines were then highlighted with ink, soot, or tobacco juice to make the images stand out.
The cultural legacy of whale teeth has shifted due to conservation efforts. The trade of sperm whale teeth is now strictly regulated under international agreements like the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and national laws like the Marine Mammal Protection Act in the United States. These regulations mean that while antique scrimshaw remains a legal collectible, creating or selling new pieces is broadly prohibited to protect sperm whale populations.