Sperm whales are among the ocean’s most recognizable and largest predators. Their distinctive physical appearance sets them apart from other marine mammals.
Overall Physical Characteristics
The most striking feature of a sperm whale is its massive, block-shaped head. This head can account for up to one-third of the animal’s total body length. This large head houses the spermaceti organ, a complex structure filled with a waxy substance crucial for echolocation and communication.
Sperm whales exhibit significant sexual dimorphism, meaning males and females differ in size. Mature males are larger than females, typically measuring around 16 meters (52 feet) in length and weighing up to 45 metric tons (50 short tons). Females are smaller, generally reaching lengths of about 11 meters (35 feet) and weighing approximately 15 metric tons (17 short tons). The body of a sperm whale is robust and somewhat stocky, tapering towards the tail, and often has a wrinkled appearance, especially behind the head.
Unique Anatomical Features
A sperm whale’s single, S-shaped blowhole is positioned on the left side of the head, close to the front. This unusual placement results in a unique bushy, forward-angled blow when the whale exhales. This blow pattern helps identify them.
The lower jaw of a sperm whale is long and narrow, appearing underslung relative to its massive head. This jaw contains between 18 and 26 prominent conical teeth on each side, which can weigh up to 1 kilogram (2.2 pounds) each. While these teeth are functional, the upper jaw typically has few or no erupted teeth, instead featuring sockets where the lower teeth fit when the mouth is closed.
Sperm whales possess small, paddle-shaped flippers compared to their body size. Their tail fins, known as flukes, are large and triangular with a deep notch in the center. These flukes are proportionally larger than those of many other cetaceans and are flexible, often lifted high out of the water at the start of a deep dive.
Skin and Coloration
Sperm whales typically exhibit a dark, grayish-brown to black coloration across most of their body. However, irregular white or lighter-colored patches can often be observed, particularly on the belly and around the mouth. The interior of their mouth is often bright white.
The skin of a sperm whale often has a wrinkled or corrugated appearance. This is especially noticeable on the head and back, contributing to a “shriveled” or “prune-like” look. This texture is thought to be a result of their deep-diving habits, which subject their skin to extreme pressure changes.