Giant isopods of the genus Bathynomus, which can reach more than 30 cm in length, are known as bọ biển or “sea bugs” in Vietnam. For the first time, one such species was described from Vietnamese waters and named Bathynomus vaderi. The name “vaderi” is inspired by the appearance of its head, which closely resembles the distinctive and iconic helmet of Darth Vader, the most famous Sith Lord of Star Wars.
Bathynomus vaderi belongs to a group known as “supergiants,” reaching lengths of 32.5 cm and weighing over a kilogram. So far, this new species has only been found near the Spratly Islands in Vietnam, but further research will probably confirm its presence in other parts of the South China Sea.
Giant isopods like Bathynomus vaderi have become an expensive delicacy in Vietnam. Until 2017, local fishermen only sold them as a bycatch product for low prices, but in recent years the media has drawn public attention to this unusual seafood. Some go as far as claiming it’s more delicious than lobster, the “king of seafood”.
These animals have been commercially fished by trawlers operating in various deep-water parts of Biển Đông ( East Sea, Vietnamese part of the South China Sea) and offshore of provinces in south-central coastal of Vietnam. Over the last five years, it has become common to see themsold alive in some seafood markets in Hanoi, Hồ Chí Minh City, and Đà Nẵng City. Some outlets and restaurants even advertise the saleof these “sea bugs” online on various social media platforms, including how best to cook them!
In March 2022, staff from Hanoi University purchased four giant isopod individuals from Quy Nhơn City and sent two of them to Peter Ng from the Lee Kong Chian Natural History Museum in the National University of Singapore for identification. Peter Ng has a very active crustacean laboratory in Singapore and has worked on the deep-sea fauna from many parts of Asia. He subsequently co-opted Conni M. Sidabalok from the National Research and Innovation Agency Indonesia, who had described Bathynomus from southern Java with him. Together with Nguyen Thanh Son from the Vietnam National University, who is the resident crustacean researcher there, they studied the specimens. In early 2023, they realised they had specimens of a so far undescribed species. Now, they have published their findings in the open-access journal ZooKeys.
The discovery of a species as strange as Bathynomus vaderi in Vietnam highlights just how poorly we understand the deep-sea environment. That a species as large as this could have stayed hidden for so long reminds us just how much work we still need to do to find out what lives in Southeast Asian waters.
There is an urgent need to better understand our deep-sea biodiversity as humans increasingly endeavour to exploit this habitat for fisheries, oil and gas, and even minerals. The sustainable fishery of giant isopods just adds to the many challenges we face. And the first step is to know what lives there.
Research article:
Ng PKL, Sidabalok CM, Nguyen TS (2025) A new species of supergiant Bathynomus A. Milne-Edwards, 1879 (Crustacea, Isopoda, Cirolanidae) from Vietnam, with notes on the taxonomy of Bathynomus jamesi Kou, Chen & Li, 2017. ZooKeys 1223: 289–310. https://doi.org/10.3897/zookeys.1223.139335
