Giant ‘Darth Vader’ sea bug discovered off the coast of Vietnam

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Scientists have newly identified a “supergiant” sea bug species after purchasing crustaceans from fishermen and restaurants in Vietnam to study the growing popularity of the creatures as a local delicacy.

The deep-sea critter, now called Bathynomus vaderi, got its name after researchers noticed its head shared a resemblance to the helmet worn by iconic “Star Wars” villain Darth Vader.

The scientists officially described the newfound species on Tuesday in the journal ZooKeys, confirming that some elements of B. vaderi’s body structure differed greatly from other Bathynomus specimens found in the South China Sea.

Supergiant sea bugs, including B. vaderi, are members of the isopod family, characterized by their hard, protective exoskeleton and seven pairs of legs. The largest specimen in the study weighed more than 1 kilogram (2.2 pounds) and measured 32.5 centimeters long (12.8 inches), making B. vaderi one of the world’s largest known isopods.

The overall body structure of Bathynomus crustaceans is similar to many shallow-water cirolanids — the isopod family it belongs to — but these deep-sea creatures have evolved to be significantly larger, according to study coauthor Dr. Conni Sidabalok, a researcher with the National Research and Innovation Agency in Indonesia.

Most isopods are incredibly small, typically measuring less than 2.5 centimeters (1 inch) in length. This disparity in size makes the discovery of such a huge specimen particularly remarkable, said Dr. Lanna Cheng, professor emeritus of marine biology at the University of California, San Diego, who was not involved in the study.

Identifying a species that’s new to science

Fishermen who caught B. vaderi were deep-sea trawling in the South China Sea about 50 nautical miles offshore of the city of Quy Nhon in south-central Vietnam, which is west of the Spratly Islands.

B. vaderi are bottom dwellers that feed on dead animals, recycling nutrients as part of the deep-sea food chain, Sidabalok said.

She noted that Bathynomus’ massive size may aid its survival in the ocean’s abyss or provide a competitive advantage over other scavengers.

Currently, there are only 11 known “supergiant” and nine “giant” Bathynomus species, with several awaiting formal description, according to the study. B. vaderi is only the second recorded supergiant isopod species discovered in the South China Sea.

However, because these crustaceans inhabit such deep waters, distinguishing B. vaderi from other species was a laborious process for the research team.

Unlike other recorded supergiant isopods, B. vaderi possesses a unique feature: The last segment of its back legs narrows at the end and curves slightly backward, according to the study.

To confirm B. vaderi’s uniqueness, Sidabalok and her colleagues examined specimens of related species from museum collections across various countries and collaborated with other experts. In addition, the researchers analyzed the DNA of B. vaderi, but the lack of genetic data for many Bathynomus species presented additional challenges in the identification process.

Vietnamese delicacy vulnerable to overfishing

In recent years, other Bathynomus species, such as B. jamesi, have become a delicacy in Vietnam, with their flesh often compared to that of lobster, according to the study.

As Bathynomus grew in popularity, in 2017 some specimens were sold for up to 2 million Vietnamese dong ($80), researchers wrote. However, as fishermen caught and sold more Bathynomus, prices dropped because the sea bugs became more widely available.

By early 2024, 1-to-2-kilogram (2.2-to-4.4-pound) specimens were being sold for around 1 million Vietnamese dong ($40), the study noted.

With the discovery of B. vaderi, scientists such as Sidabalok and Cheng have raised concerns about its potential integration into global seafood markets.

Bathynomus are known for their slow reproduction. These supergiant crustaceans produce a small number of eggs — only in the hundreds — which hatch as miniature versions of the adults, Sidabalok said. She added that this slow reproduction rate makes them especially vulnerable to overfishing.

“These (creatures) don’t grow very fast, and if they become a very unusual and sought-after item, we may eat them out of existence,” Cheng said.

The research team believes B. vaderi exists beyond Vietnam’s coastal waters in other parts of the South China Sea, but uncovering other species in these depths will take time.

Sidabalok said she hopes this research will pave the way for further research into Bathynomus populations and help fishermen develop more sustainable practices.

“If we get the chance, we would like to do more surveys and perhaps work with scientists in the region to ascertain what is living there,” Sidabalok said. “There is still so much to learn and discover.”

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