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Are Lobsters Really Immortal?

Lobster under water on a rocky ocean bottom
OSDG/Shutterstock

That lobster trapped behind glass in the grocery store might be older than you thought: lobsters are biologically immortal. But does that mean they live forever?

The term biological immortality might seem to suggest so, but lobsters actually do die. However, biological immortality is a fascinating natural feature that might teach us some things about living longer. So, how do lobsters live so long, and where did the myth of lobster immortality come from? Let’s take a look.

What Is Biological Immortality?

Biological immortality probably isn’t the best term for this phenomenon. As biologist Thomas Bosch told the BBC, “Immortal really means you don’t die at all, which is stupid.” However, it’s hard to deny that the term is kind of catchy.

And biologically immortal creatures do hold something akin to the immortality humans have long dreamed of: they don’t age. Sure, they can still be killed by outside forces. Inevitably, as it grows older, a lobster will run into a deadly threat or disease. But it won’t die of old age before that.

Lobsters produce an enzyme called telomerase. This enzyme prevents DNA damage that happens when cells replicate, which is believed to be the cause of aging. With cells that can replicate without damage, lobsters stay forever young.

How “Immortal” Lobsters Die

As lobsters age, they continue to grow, so the bigger the lobster, the older it is. Presumably, if an ageless lobster were lucky enough to avoid predators, disease, and natural disasters, it would live forever and slowly become a giant—right?

Unfortunately, that’s not entirely true. While lobsters don’t age the same way humans do, their aging does take a toll on their bodies.

As lobsters grow, they molt. Each time a lobster molts, it sheds its old exoskeleton and grows a new bigger one, becoming larger and heavier in the process. The biggest lobster ever recorded weighed 44 pounds! Though some estimated his age at over 100 years, marine biologists claim that 30 to 50 years is more likely.

The process of shedding and growing a new exoskeleton is incredibly stressful on a lobster. Even if a lobster manages to avoid predators during this vulnerable process, the sheer effort of molting can sometimes be enough to kill them.

And the bigger the lobster, the more energy it takes to molt. Eventually, the lobster simply stops shedding completely, because older larger lobsters don’t have enough energy left for the task.

Without molting, these old lobsters eventually contract bacterial infections and shell disease, where scar tissue from bacteria causes the lobster to get stuck to its shell. When a lobster with shell disease tries to molt, it will die from the effort. And, even if the lobster doesn’t try to molt again, being trapped in the same shell year after year makes it more likely to get another deadly disease.

Thus, even if a lobster is kept in perfectly safe conditions, it will eventually die. They may not die of old age, specifically, but they will die from other factors related to aging and molting. So, although you might call a lobster “biologically immortal,” lobsters are far from being immortal in the true sense.

Where the Lobster Immortality Myth Began

Last year, some viral social media posts popularized the idea that lobsters are immortal, which scientists quickly debunked. However, the myth of immortal lobsters is probably quite a bit older.

After all, creatures of the sea have long been misunderstood, mainly because it’s hard for land-dwelling humans to observe them accurately. It seems likely that fishermen from long ago who found the occasional massive lobster may have thought that they kept growing and getting older forever. Today, though, social media plays the primary role in carrying on this myth.

Lobsters may not be genuinely immortal. But they certainly are fascinating, thanks to their ability to grow without aging. And, if you were hoping for real immortal animals, don’t be disappointed—some kinds of jellyfish appear to be truly capable of living forever.

Elyse Hauser Elyse Hauser
Elyse Hauser is a Seattle-based writer and editor with a Master's in Writing Studies from Saint Joseph's University. Her work has appeared in publications like Racked, Vine Leaves Literary Journal, and Rum Punch Press. She was awarded a 2017 Writing Between the Vines residency.  Read Full Bio »