Now and again, photos of lobsters circulate on social media with captions calling the crustaceans biologically immortal. What does this claim mean and is this fun fact actually true?
This viral tidbit points to the fact that lobsters don’t show typical signs of what we call senescence. In plain terms, lobsters don’t age the way other living creatures do—they don’t lower their reproductive ability, slow their metabolism or decrease in strength. This has led to extrapolations that lobsters, if left undisturbed, can’t die.
But, while it’s true that lobsters continue eating, reproducing and growing until the end, there is an end—they’re not immortal.
Lobsters continue to grow until they die of natural causes or are killed. So, what does a natural death look like for a lobster?
It has to do with molting. Lobsters grow by molting their hard exoskeleton. They do this a lot: the average lobster can molt 44 times in its first year. By age seven, they molt once a year, and after that, once every two to three years, growing larger every time.
But molting is a stressful process, and between 10 and 15 percent of lobsters die each year as they shed their exoskeletons because the exertion proves to be too much. Each molting takes more energy than the one before it. Finally, older crustaceans run out of the energy to molt. Plus, their shells contract bacterial infections that weaken them. They die trapped inside their shells.
So, it’s true that lobsters can live long lives of several decades, with variations from species to species. Yet, one thing is certain: no lobster is immortal.