Smithsonian Magazine · People & society

Deep-Sea Isopods Survive Long Fasts Via Large Stomachs and Stolen Genes

Giant isopods, large deep-sea crustaceans resembling oversized pill bugs, can survive for over five years without food. New research suggests this remarkable endurance is due to a combination of a massive stomach and a gene acquired from bacteria millions of years ago.

Deep-sea survival is challenging due to darkness, cold, high pressure, and scarce food. Giant isopods, found at depths up to nearly 7,000 feet, can grow between 11 and 20 inches long.

Researchers studied two giant isopod species, Bathynomus jamesi and B. doederleini, along with an intertidal isopod. They found that the deepest-dwelling species, B. jamesi, possessed a stomach occupying about two-thirds of its body cavity, likely for food storage.

Both deep-sea species had a gene called ND1. In B. jamesi, this gene appears to slow energy production, aiding starvation tolerance. In contrast, B. doederleini, living in a food-richer area, had fewer copies of the gene.

Experiments with genetically engineered zebrafish showed that the ND1 gene reduced metabolic rates in cold temperatures. Food-deprived zebrafish with the gene lived 37% longer at 64°F compared to normal fish.

Genetic analysis indicates that giant isopod ancestors acquired the ND1 gene from a bacterium over 16 million years ago, a rare event involving gene transfer between vastly different organisms.

This gene provides isopods with an additional mechanism to regulate energy use, particularly for slowing down metabolism when necessary. The discovery offers insights into deep-sea gigantism and adaptation.

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