A 120-year-old saltwater crocodile, Cassius, died last year from sepsis caused by a dormant infection that remained contained within his body for over four decades. The case, revealed by a necropsy conducted by the Center for Crocodile Research in Darwin, highlights the unique resilience—and ultimate vulnerability—of reptiles to long-term infections.
The Silent Threat: Encapsulated Infection
Sally Isberg, managing director of the research center, explained that Cassius harbored an infection stemming from an injury sustained in the wild before his capture in 1984. Crocodiles can encapsulate infections within fibrous tissue, effectively sealing them off for extended periods. This is unlike mammals, where such infections would typically manifest as abscesses.
However, the containment isn’t permanent. In Cassius’s case, the fibrous casing, or “fibrosis,” finally ruptured near his left lung in November, unleashing the decades-old infection and leading to rapid sepsis. Remarkably, just 17 days before his death, Isberg found no visible signs of illness during a health checkup.
Injury and Age: The Double Blow
The original injury likely occurred when Cassius lost his front left leg as a juvenile. The necropsy revealed that the infection was linked to damage in his left rib cage, which had been distended by the growing fibrosis. As Cassius aged, his body’s ability to maintain the fibrous casing deteriorated, ultimately causing it to burst.
“He was not able to continue [making] that fibrous casing around that infection,” Isberg stated. This emphasizes that even in long-lived reptiles, cellular decay eventually compromises defense mechanisms.
Age Estimation Remains Uncertain
Marineland Crocodile Park celebrated Cassius’s 120th birthday in 2023, but his age was always an estimate. Researchers attempted to confirm his age by analyzing growth rings in his thigh bone, but the stable temperatures at the park made it impossible to get an accurate reading. Growth rings in crocodile bones are only reliable when metabolism fluctuates—something that doesn’t occur in a controlled environment.
Despite the uncertainty, Cassius’s lifespan remains extraordinary. His body has now been taxidermied and will be featured in an exhibit at Marineland Crocodile Park.
The death of Cassius serves as a stark reminder that even the most resilient creatures are susceptible to the long-term consequences of injury and the inevitable effects of aging. The case underscores the complex interplay between infection, immunity, and longevity in reptiles, providing valuable insights for wildlife conservation and veterinary science.
