The sperm whale, Physeter macrocephalus, is the largest toothed predator on Earth, spending most of its life in the ocean’s dark depths. When these massive marine mammals surface, their bodies, especially the enormous, block-shaped head, are often heavily marred. These abundant scars are not random blemishes but are a record of the whale’s life history, signifying intense battles fought in the deep ocean and aggressive social encounters.
The Primary Cause: Male Competition and Aggression
The most prominent scars found on mature bull sperm whales are long, parallel, linear rake marks. These deep grooves result from intraspecific fighting, primarily observed between males competing for dominance and access to breeding females. Although sperm whales do not need their teeth for catching soft-bodied prey, their lower jaw teeth have evolved into formidable weapons used almost exclusively in these conflicts.
During a fight, two bull males often ram one another head-first, a behavior supported by the dense structure of the whale’s forehead, known as the “junk.” After the impact, one male will rake its opponent’s skin with its lower jaw teeth, leaving behind characteristic parallel gouges. These battles are frequent among large bachelor males, leading to heavy scarring on the head and flanks. The degree of scarring often increases with the male’s body length and is correlated with sexual maturity.
Marks of the Deep: Battles with Giant Squid
A second major source of the sperm whale’s body markings comes from its primary prey: the giant and colossal squid. These deep-sea hunts often result in distinct, circular or oval scars, contrasting sharply with the linear marks from whale combat. These rounded imprints are left by the powerful suckers lining the arms and tentacles of the massive cephalopods.
Colossal squid suckers also possess sharp, rotating hooks that can slice into the whale’s skin. Whales commonly sustain these injuries around the head and facial region while attempting to subdue their struggling prey. Although the squid is swallowed, the violent struggle leaves permanent evidence of the encounter. Less common, deeper slashes can sometimes be attributed to the razor-sharp beak of a very large squid.
The Context of Scars: Age, Status, and Other Factors
The total accumulation of scars acts as a visual biography, indicating the whale’s age and history of successful conflict navigation. Older, larger males, having survived numerous fights and hunts, are the most heavily scarred individuals. This extensive marking signals the individual’s experience and status within the male social hierarchy.
Scar Healing and Minor Causes
Cetaceans lack hair, and their skin is susceptible to cuts and abrasions, causing wounds to heal differently than those on land mammals. As the injury heals, the scar tissue frequently lacks the original skin pigment, making it appear noticeably white against the whale’s dark skin. Minor scarring can occasionally result from environmental abrasions, encounters with predators like orcas, or entanglement with fishing gear. However, the vast majority of visible marks trace back to either a rival male’s teeth or a giant squid’s suckers.