Scientists Found a New Giant Isopod Hiding in Plain Sight

A giant isopod that sat unnoticed in a German museum collection for roughly four decades has turned out to be a species new to science. Researchers at the University of Tübingen gave the foot-long crustacean the name Bathynomus tuebingoborikensis, honoring both their university town and Boríken, the Indigenous Taíno name for Puerto Rico, where the specimen was collected, as reported by Phys.org. The giant isopod, measuring 32.2 centimeters (12.7 inches) from antenna to tail, belongs to a heavyweight class the team calls "colossogiants."

Giant isopods are among the largest invertebrates on the planet: a single giant isopod can reach 50 centimeters (20 inches) and weigh several kilograms, and these animals roam the seafloor down to 2,500 meters (8,200 feet) as omnivorous scavengers. Yet despite that scale, the giant isopod shares its basic body plan with the humble woodlouse: the roly-poly that curls into a ball under garden stones and in damp basements is a close land-dwelling relative, just built at a fraction of the size. That contrast is a textbook case of deep-sea gigantism, the pattern in which deep-ocean animals grow far larger than their shallow-water kin.

The specimen's path to scientific recognition reads like a slow-motion detective story. In the 1980s, Tübingen paleontologist Dolf Seilacher (1925–2014) obtained the dried animal at a research station in Puerto Rico and carried it back to Germany as teaching material. There it rested, unremarked, in the university's Paleontological Collection while decades passed. When isopod specialist Benedikt Kästle and collection curator Ingmar Werneburg re-examined the dried animal with modern imaging techniques, subtle anatomical differences set it apart from every known species. A phylogenetic analysis then placed it on its own Caribbean branch of the family tree, and the 2026 paper describing it appeared in the journal Scientific Reports.

How this giant isopod conquered the world's oceans

The new species is not just a curiosity — it is a clue to how the whole genus Bathynomus spread across the planet. According to the researchers' evolutionary reconstruction, the genus arose in what is now the Gulf of Mexico more than 15 million years ago, during the Miocene. At the time, the Isthmus of Panama was still open, leaving a strait between North and South America, and the giant isopod ancestors pushed westward as far as Japan. Across the Indian and Pacific oceans they diversified into many species: the so-called "giants" reaching up to 15 centimeters (5.9 inches) and the "supergiants" growing beyond 15 centimeters.

From there they ranged to Australia, East Africa and, before the Arabian and African continental plates collided, Europe — where they died out at the end of the Miocene. Then the planet cooled. At the Miocene–Pliocene boundary, 5.333 million years ago, a new group of veritable colossi evolved in the Indo-Pacific, growing to more than 25.2 centimeters (9.9 inches) and physiologically tuned to the colder conditions. This giant isopod lineage spread from Australia via Antarctica to South and Central America, where the colossi met their smaller, more distant relatives that had stayed behind after the genus's first westward push. The Caribbean animal falls squarely in the colossus group, Kästle noted, and it is very closely related to another giant species found off Mexico's Yucatán Peninsula.

Why a giant isopod can skip meals for years

Surviving in the deep sea means enduring famine, and giant isopods are champions of it. Some can go more than five years between meals. Researchers who sequenced the genomes of two deep-dwelling species found one secret is a cavernous stomach that can fill around two-thirds of the body cavity, acting as a pantry for gorged meals of scavenged fish and carrion. The other is a stolen piece of genetic hardware: more than 16 million years ago, the animals' ancestors picked up a bacterial gene called ND1 that helps throttle energy production in the cold, according to Smithsonian Magazine. In lab tests, food-deprived zebrafish carrying the gene lived 37 percent longer at a chilly 64 degrees Fahrenheit than ordinary fish.

That hardiness has a darker side. In Vietnam, giant isopods are sold as high-end live seafood under the name "bọ biển," and demand at live markets has surged in recent years, putting new pressure on deep-sea trawl catches. Researchers who described a related new species in 2022 warned that precise species identification is essential for managing such fisheries — managers need to know exactly which species are being caught, and where. The deep sea remains one of the least surveyed habitats on Earth, which means exploitation can outrun understanding. Every new species pulled from a museum drawer, like the Puerto Rico animal, sharpens the picture of which giant isopod species actually live down there before one ends up on a plate.

The biggest lesson, though, may not be about one crustacean. Werneburg points out that natural history collections are global archives of nature: a single dried specimen can wait decades and still rewrite an entire group's evolutionary history once someone looks closely enough. If a foot-long animal hid in plain sight in a teaching collection for some forty years, the world's museum drawers are almost certainly holding more species that science has not met yet. For more science coverage, browse the Science topic page, and see also how ancient viral DNA built embryos — and cancer stole the trick.