Do Lobsters Live Forever? The Immortal Lobster Myth

Where did the immortal lobster idea come from?

The idea grew from real biology. In 1998, a team of researchers reported in the journal FEBS Letters that lobsters produce telomerase in all of their organs as adults. In most animals, including people, this enzyme is active mainly in embryos and a few special cells. The researchers suggested that the enzyme could help explain why lobsters live so long.

Other observations added to the picture. Lobsters keep growing throughout life, and older, larger lobsters do not seem to slow down, weaken or lose fertility the way many animals do. Big females actually carry far more eggs than small ones. Biologists call this “negligible senescence”: aging that is so slow it is hard to detect.

From there, the claim spread online and turned into a popular meme: lobsters are “biologically immortal” and would live forever if nothing killed them. The truth is more interesting and less dramatic.

What does telomerase do?

Each of an animal’s chromosomes is capped at both ends by repeated stretches of DNA called telomeres. Every time a cell divides, its telomeres get a little shorter. When they become too short, the cell stops dividing or dies, which is one of the processes behind aging.

Telomerase rebuilds telomeres. Having it active in adult tissue means lobster cells can keep dividing, which fits with an animal that grows and repairs itself for decades. But telomerase does not stop an animal from dying. It does not protect a lobster from injury, infection, starvation or the huge physical cost of molting.

Why do lobsters still die?

The main limit is molting. A lobster’s hard shell cannot grow, so the animal must shed it and build a bigger one. Each molt takes a great deal of energy, and the bigger the lobster, the more energy it needs. A lobster can get stuck in its old shell, be too exhausted to finish the molt or be attacked while its new shell is still soft. The risk is thought to rise as a lobster gets larger.

To save energy, big lobsters molt less often, from about ten times in their first year to once every few years as adults. Some very old lobsters seem to stop molting altogether. Their old shells then wear down and become infected with bacteria that cause shell disease, which eats holes into the shell. Without a molt to replace it, the shell can break down until the lobster dies.

Most lobsters never get that far. Only about one larva in 1,000 is thought to survive its first weeks of drifting in the plankton. Young lobsters are eaten by fish, crabs, octopuses and seals, and adults face disease, warming water and fishing. In heavily fished areas, few lobsters live long past the minimum legal size, which they reach at about 5–8 years old.

How long do lobsters actually live?

Estimates vary because lobster age is so hard to measure. NOAA Fisheries says some American lobsters may live to be about 100 years old. Other scientists put the maximum age at a few decades, with figures of around 45–50 years often cited for wild lobsters.

Famous giant lobsters are often given extreme ages. In 2009 a New York restaurant released a 9.1 kg (20 lb) lobster nicknamed George, caught off Newfoundland, after an animal-rights campaign. News reports gave his age as about 140 years, but that figure was a rough estimate based on his size, not a measured age. Because growth rates depend on water temperature and food, two lobsters of the same size can differ in age by many years. You can read about record sizes in how big do lobsters get?

How do scientists tell how old a lobster is?

A lobster sheds its whole shell when it molts, so it carries no permanent growth rings like a tree trunk, a clam shell or a fish’s ear bone. Scientists have tried several workarounds:

• Growth models: tagging lobsters and measuring how much they grow per molt and how often they molt, then working out how long it takes to reach a given size.
• Age pigment: a fatty pigment called lipofuscin builds up slowly in nerve tissue, including the brain and eyestalks, and its amount gives an age estimate.
• Stomach bands: in 2012, researchers in Canada reported growth bands in the hard, tooth-like plates of the stomach (the gastric mill) of lobsters, crabs and shrimps, which appeared to form once a year. Later studies questioned whether these bands survive molting, so the method is still debated.
• DNA changes: more recently, scientists have estimated the age of European lobsters from chemical tags on their DNA, which change in a predictable way over time.

None of these methods is yet precise enough to give the exact age of a very old wild lobster.

Are any animals really immortal?

Truly immortal animals do not exist, because every animal can be eaten, injured or killed by disease. A few species, however, show no clear signs of aging. The tiny jellyfish Turritopsis dohrnii can turn back from an adult into a young polyp and start its life cycle again, as explained in how long do jellyfish live?. Freshwater hydras also show no rise in death rates with age in laboratory studies.

Lobsters belong to a different group: animals that age so slowly that they can live for many decades. For record holders such as Greenland sharks, bowhead whales and ocean quahog clams, see the longest-living animals.