You've probably heard that lobsters are "biologically immortal" and can live forever if nothing kills them. It's become one of those facts people love to share at parties. The problem? It's completely wrong. Lobsters do die of old age, but the reason they die is so bizarre it almost makes the immortality myth seem reasonable.
Here's where the myth comes from: lobsters produce an enzyme called telomerase that most animals don't have in abundance. In humans and most creatures, our DNA deteriorates every time our cells divide because the protective caps on our chromosomes (telomeres) get shorter. Eventually, cells can't divide anymore and we age and die.
Lobsters' cells produce so much telomerase that their telomeres don't shorten the same way. Their DNA doesn't deteriorate with age like ours does. They don't show typical signs of aging—they don't get weaker, their organs don't fail, and they actually become more fertile as they get older. A 100-year-old lobster is biologically similar to a 10-year-old lobster.
So if they don't age, why do they die? Because lobsters never stop growing, and that growdth eventually kills them in the most exhausting way possible. Lobsters grow by molting—they literally shed their entire shell and grow a new, bigger one. When they're young, this happens frequently and easily.
But as lobsters get larger and older, molting becomes increasingly difficult and energy-intensive. A giant lobster has to produce an enormous amount of new shell material, and the process of shedding the old shell becomes dangerous. The lobster has to absorb water to swell up and crack open its old shell, then pull its entire body out—including pulling its eyeballs through the eye sockets of the old shell.
Eventually, molting requires so much energy that the lobster can't sustain it anymore. Some lobsters die of exhaustion during the molting process. Others successfully molt but are so weakened and vulnerable in their soft new shell that they get eaten by predators or die from infections before the shell hardens.
Even if a lobster somehow survives molting indefinitely, there's another problem: they become too big to function properly. A lobster's shell doesn't just protect them—it's their skeleton. As they grow massive, moving becomes increasingly difficult. Their own weight makes it harder to walk, hunt, and escape predators.
Scientists estimate that lobsters probably can't survive much beyond 100 years, though measuring their exact age is difficult. The largest lobster ever caught was 44 pounds and estimated to be around 140 years old. It likely would have died soon from molting failure even if it hadn't been caught.
There's also disease. Older lobsters are more susceptible to shell disease, where bacteria eat through their shells. Without the ability to heal their shells between molts the way younger lobsters can, these infections can become fatal.
So no, lobsters aren't immortal. They just die in a uniquely weird way—not because their bodies wear out like ours do, but because they literally outgrow their ability to survive. They don't age in the traditional sense, but their endless growth becomes their own death sentence. Nature found a way to kill them anyway, just through exhaustion rather than deterioration.