The lobster is a marine creature known for possessing a lifespan that can significantly outpace that of many land mammals. Species like the American lobster, living in the North Atlantic, can live for many decades. This impressive longevity has led to persistent, though inaccurate, rumors of biological immortality. Determining the exact age of these crustaceans is challenging because they shed their entire exoskeleton as they grow, eliminating common biological records of age. Scientists have had to develop specialized techniques to peer into the life history of these long-lived ocean dwellers.
Documenting Extreme Longevity
The American lobster (Homarus americanus) is noted for its extreme lifespan, with estimates suggesting some individuals can live for 50 to over 100 years in the wild. The European lobster (Homarus gammarus) also exhibits remarkable longevity, with estimates for wild populations ranging up to 72 years for some females. For many years, determining a lobster’s age was a rough estimation based primarily on size, but this proved unreliable since growth rates depend heavily on factors like water temperature and food availability.
More accurate aging methods have emerged, focusing on internal structures that are not shed during molting. Scientists can now count growth rings found in the gastric mills, the calcified, tooth-like structures inside the lobster’s stomach. Rings are also present in the eyestalks, providing a more precise, though destructive, way to determine the animal’s age. The newest scientific technique involves DNA methylation, which quantifies changes in the lobster’s DNA that accumulate predictably over time. By calibrating this “molecular clock” using lobsters of known age, researchers gain a non-invasive tool to estimate the true age of wild specimens.
The Biological Secret to Aging Slowly
The lobster’s extended lifespan is rooted in a biological trait known as negligible senescence. This means that unlike humans and many other animals, lobsters do not show a measurable decline in reproductive capacity or metabolic function as they age. They continue to grow and remain fertile, challenging the typical pattern of age-related deterioration seen across most of the animal kingdom.
This longevity is linked to the function of telomeres, the protective caps on the ends of chromosomes that shorten each time a cell divides. In most organisms, this shortening leads to cellular aging and eventual death. Lobsters, however, possess a high concentration of the enzyme telomerase in virtually all their adult tissues. Telomerase acts as a repair mechanism, continuously rebuilding the telomeres and preventing them from shortening. This constant maintenance allows lobster cells to divide far more times than those of most other animals, allowing its body to repair and regenerate tissue throughout its life.
Why Lobsters Are Not Immortal
Despite their biological defenses against cellular aging, the idea that lobsters are biologically immortal is a misconception. They do not die from old age in the way that humans do, but they are not immune to mortality.
The greatest intrinsic risk to a large, old lobster is related to its continuous growth: the molting process. As lobsters increase in size, shedding their hard exoskeleton demands an exponentially greater amount of energy and physical effort. This difficult process can lead to death from exhaustion, with estimates suggesting that 10 to 15 percent of lobsters die during or immediately after a molt.
For the largest and oldest individuals, the shell may become too heavy or the energy expenditure too great, causing the animal to stop molting altogether. When this happens, the old shell degrades, becomes susceptible to bacterial shell disease, or collapses, leading to the lobster’s eventual death. Additionally, lobsters remain vulnerable to external factors such as predation, environmental changes, and injuries.