A new species of branching seaworm has dozens of regenerating hind limbs that separate and swim during reproduction. This strange superpower led the monster discoverers to name it after Godzilla’s monstrous multi-headed enemy, King Ghidorah.
In total, 25 new worms were named Ramisyllis kingghidorahi After the evil kaiju, she was found living inside a sea sponge in Japan in October 2019. Unlike her namesake, who has three heads and tails, R. kingghidorahi It has only one head but has many hind branches, which grow to fill the narrow tubes within the host sponge, which are between 2 and 4 inches (5 and 10 cm) long.
As the worms reproduce, the end of each branch, known as a stolon, detaches and swims to the surface to release eggs or sperm, which then mix into the water column, where fertilization occurs. The worms die, but the worms remain safely in their spongy host and replenish the lost parts of each branch for the next reproductive cycle.
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“King Ghidorah is an imaginary branching animal that can replenish its lost ends. So we thought that was a suitable name for the new species of branching worms,” said lead author Maria Teresa Aguado, an evolutionary biologist specializing in marine invertebrates at the University of Göttingen in Germany. He said in a statement.
R. kingghidorahi It is the third type of branching sea worm ever discovered. The first types are now called Siles RamosaFound in 1879 in the Philippines. The second, Ramisyllis multicaudata (of the same sex R. kingghidorahi), was detected in 2006 in northern Australia and named in 2012. A study released in May 2021 revealed that R. multicaudata It can contain about 100 branched segments, Live Science previously reported.
Different species also choose different sponges as homes: S. Ramosa Live inside a glass sponge in the deep sea, while the two Ramiselles Sponges prefer stone sponges in shallow water. According to the researchers, there are likely to be more branching sea worms waiting to be discovered. However, elusive invertebrates are hard to find because they spend most of their lives hidden within their spongy host.
“We were surprised to find another one of these strange creatures,” Aguado said in the statement. Genetic differences between R. kingghidorahi And R. multicaudataDescending from the same common ancestor, she added, there is much more diversity among branching sea worms than expected.
The researchers now want to explore the unique and mysterious relationship between the worms and their sponge hosts.
“We do not yet understand exactly what the relationship between the worm and its host sponge is,” Aguado said in the statement. It can be symbiotic, which means it is mutually beneficial to the worm and the sponge, or parasitic, in which the worm benefits at the expense of the host sponge.
The researchers are also unsure how the worms are able to access enough food inside the sponge to continue growing new branches and replenishing lost branches — processes believed to be very costly, according to the statement.
The study was published online January 19 in the journal Diversity and evolution of living things.
Originally published on Live Science.