Deep in the ocean, where food is scarce and sunlight never reaches, lives a strange giant crustacean known as the supergiant isopod.
These armored creatures, which resemble enormous pill bugs, have fascinated scientists for years because of their incredible ability to survive without food for more than five years.
This remarkable feat has long puzzled researchers.
Supergiant isopods can grow to impressive sizes, and large bodies usually require large amounts of energy.
How can such a giant animal survive in one of the most food-poor environments on Earth?
A team of scientists from the Institute of Oceanology of the Chinese Academy of Sciences has now uncovered the answer.
Their study reveals that these deep-sea animals use a clever two-part survival system that allows them to thrive despite long periods without food.
The researchers studied two species of giant isopods living at different ocean depths. One species, Bathynomus jamesi, lives nearly 900 meters below the surface, while Bathynomus doederleini lives at depths of around 300 meters.
The first key to their survival is an enormous stomach. Scientists found that the stomach occupies about two-thirds of the animal’s body. Compared with related species living in shallower waters, the deep-sea isopod’s stomach is exceptionally large.
When food becomes available, these animals appear to eat as much as possible. Their stomachs can become packed with a thick, mud-like mixture of partially digested food. This huge storage space allows them to stockpile nutrients during rare feeding opportunities and slowly use those reserves over a very long time.
The second part of their strategy is conserving energy. The researchers found that giant isopods have an extremely low basal metabolic rate, meaning their bodies use very little energy while at rest. By dramatically reducing energy consumption, they can stretch their stored food supplies for years.
The team also discovered an unusual genetic adaptation that may help these animals manage their energy use. They identified a gene called ND1 that appears to have originally come from a symbiotic bacterium and later became part of the isopod’s own genome.
To understand how this gene works, the researchers inserted it into zebrafish, microscopic worms, and human cells. Under normal temperatures, the gene increased energy use, causing the organisms to burn through their resources more quickly and making them less resistant to starvation.
However, when temperatures were lowered to mimic the cold conditions of the deep sea, the gene had the opposite effect. It reduced energy metabolism and lowered activity in the cells’ mitochondria, which are responsible for producing energy. As a result, zebrafish carrying the gene were able to survive starvation about 37% longer than normal fish.
The findings suggest that the ND1 gene helps giant isopods carefully adjust their metabolism to match the cold deep-sea environment. Combined with their huge food-storage stomachs, this allows them to balance the energy demands of their large bodies with the need to survive extended periods without eating.
The study provides new insight into how life adapts to extreme environments. It also reveals an elegant solution to a difficult biological challenge: how to grow large while living in a place where food may not arrive for years.
For the giant deep-sea isopod, the answer is simple—eat big when you can and spend energy as slowly as possible.
