A newly discovered species of branched sea worm has dozens of regenerative hindquarters that loosen and swim off during reproduction. This strange superpower made the beast’s discoverers name it after Godzilla’s monstrous multi-headed enemy, King Ghidorah.
In total, 25 of the new worms are named Ramisyllis kingghidorahi after the villain kaiju, were found alive inside a sea sponge in Japan in October 2019. Unlike their namesake, which has three heads and two tails, R. kingghidorahi have only one head but have several posterior branches which grow to fill narrow tubes inside their host fungi which were between 2 and 4 inches (5 and 10 centimeters) long.
As the worms multiply, the end of each branch, known as a stolon, loosens and swims to the surface to release its eggs or sperm, which are then mixed into the water column where fertilization takes place. The stolons die, but the worms remain safe in their spongy hosts and regenerate the lost parts of each branch for the next reproductive cycle.
Related: The 12 strangest animal discoveries
“King Ghidorah is a branched fictitious animal that can regenerate its lost ends. So we thought this was an appropriate name for the new species of branching worm,” main author Maria Teresa Aguado, an evolutionary biologist specializing in marine invertebrates by University of Göttingen, Germany, said in a statement.
R. kingghidorahi is the third species of branching sea worm ever discovered. The first species, now called Syllis ramosa, was found in 1879 in the Philippines. The second, Ramisyllis multicaudata (from the same genus as R. kingghidorahi), was unveiled in 2006 in northern Australia and was named in 2012. A study published in May 2021 revealed that R. multicaudata can have about 100 branch segments, Live Science previously reported.
The different species also choose different fungi as home: S. ramosa live inside deep-sea glass fungi while the two Ramisyllis fungi prefer stone fungi in shallow water. There are probably more branched sea worms waiting to be discovered, according to the researchers. However, finding the elusive invertebrates is a challenge because they spend most of their lives hidden in their spongy hosts.
“We were amazed to find yet another of these bizarre creatures,” Aguado said in the statement. The genetic differences between R. kingghidorahi and R. multicaudata, who is descended from the same common ancestor, also highlights that there is much more diversity among branched sea worms than expected, she added.
The researchers will now explore the unique, mysterious relationship between the worms and their fungal hosts.
“We do not yet understand exactly what the relationship between the worm and its host fungus is,” Aguado said in the statement. It can be symbiotic, meaning that it is mutually beneficial to the worm and the fungus, or parasitic, where the worm benefits at the expense of its host fungus.
Researchers are also unsure how the worms manage to gain access to enough food inside the mushrooms to continue growing new branches and regenerating lost ones – processes that are thought to be very energetically expensive, according to the statement.
The study was published online Jan. 19 in the journal Diversity and evolution of organisms.
Originally published on Live Science.