This Deep-Sea Animal Can Go 5 Years Without Eating

• Study identifies dual survival strategy in deep-sea supergiant isopods
• Isopods store large food reserves and maintain low metabolic rates
• Researchers found bacterial-origin gene regulating energy metabolism
• Gene reduces energy use in cold, increasing starvation tolerance

At roughly 300 to 900 metres below the ocean surface, food does not arrive on a schedule. It arrives when something dies above and sinks, a whale carcass, a shower of organic debris, an event that may not happen again for months or years.

For most animals, this would be a death sentence. For the supergiant isopod, a crustacean distantly related to the common pill bug and roughly the size of a tablet computer, it is simply Tuesday. How an animal that large survives that long without eating has been an open question in deep-sea biology for years.

A study published Friday in the journal Cell by researchers at the Institute of Oceanology of the Chinese Academy of Sciences, in collaboration with the Chinese University of Hong Kong and Northwestern Polytechnical University, now has a precise answer. It involves a gene that the isopod does not technically own.

A Two-Part System, and One Surprising Source

The researchers studied two species, Bathynomus jamesi, collected from approximately 898 metres depth, and Bathynomus doederleini from around 300 metres, using a combination of genomic analysis, physiological measurement, and lab experiments.

What they found was a dual survival strategy. The first part is structural: the isopod’s stomach occupies roughly two-thirds of its body, functioning as an oversized storage organ that allows it to consume large quantities of food when available and draw on those reserves for extended periods afterward.

The second part is metabolic: the animal maintains an exceptionally low basal metabolic rate, keeping energy expenditure close to the minimum required to stay alive. Together, the researchers describe this as an “increase revenue, reduce expenditure” approach to survival. Neither feature alone is sufficient.

Both together produce an animal that can, under the right conditions, go more than five years between meals. That figure comes from captivity observations of the species reported in prior literature, which the current study draws on but did not independently establish. The more unexpected finding was what drives the metabolic side of this system.

The Gene That Came From Bacteria

The most surprising discovery involved a gene known as ND1.

Researchers found evidence that the gene was not inherited through the isopod’s normal evolutionary lineage. Instead, genomic analyses suggest it was acquired from a symbiotic bacterium through horizontal gene transfer — the movement of genetic material between unrelated organisms.

Horizontal gene transfer is common among bacteria, where it helps spread traits such as antibiotic resistance. In animals, however, functional examples are comparatively rare and remain an active area of research.

According to the study, ND1 became integrated into the isopod genome and evolved into a key regulator of energy metabolism.

The gene influences mitochondrial activity, controlling how quickly cells consume energy. Scientists believe this adaptation became particularly valuable in the cold, food-poor conditions of the deep sea.

A Metabolic Switch Triggered by Cold

To test the gene’s function, researchers inserted ND1 into zebrafish, nematodes and human cells.

The results were unexpected.

Under normal temperatures, organisms carrying the gene showed higher energy consumption and reduced tolerance to starvation. But when researchers lowered temperatures to mimic deep-sea conditions, the effect reversed.

Under colder conditions, ND1 suppressed metabolic activity, reduced mitochondrial energy use and increased starvation resistance. In zebrafish, survival under food deprivation improved by approximately 37 percent.

The findings suggest that ND1 functions as a temperature-sensitive metabolic switch. In the cold deep ocean, where energy conservation is essential, the gene helps suppress unnecessary energy expenditure and prolong survival.

Researchers describe this mechanism as helping solve an “energy paradox” that has puzzled biologists for years: how a relatively large animal can persist in an environment where food may be absent for months or even years at a time.

Implications Beyond the Deep Sea

While the study’s most immediate significance lies in evolutionary biology, it also highlights how organisms can adapt to extreme environments through unexpected genetic innovations.

The researchers caution that potential applications to human health, metabolism or longevity remain speculative. The experiments involving human cells merely demonstrated that the gene remains functional outside the isopod and do not indicate that it would have similar effects in people.

Instead, the study’s major contribution is revealing a remarkable example of evolutionary adaptation.

“Our work not only successfully deciphers the mystery of ultra-long starvation tolerance in deep-sea isopods,” said first author Yuan Jianbo, “but also provides an important paradigm for understanding how life balances growth and survival in extreme environments.”

The discovery suggests that one of the deep ocean’s most iconic scavengers may owe part of its success to an ancient genetic contribution from bacteria — a borrowed tool that evolved into a sophisticated system for surviving one of the harshest environments on Earth.