New species of branching worms discovered in waters off Japan – Archyde

Marine biologists have described a third species of branched syllid worm – and the second within the genus Ramisyllis — Life in an undescribed species of the genus of sponges Petrosia Found in shallow waters off Sado Island, Japan.

Among over 20,000 types of Anneliden (Ringworms or segment worms) only two branching species with strongly modified body structure were previously known: Syllis ramosa and Ramisyllis multicaudata.

Both have unusually branched bodies with a head and multiple branches, and live in the ducts of host sponges.

“In 1879, the Scottish physician and marine zoologist William Carmichael M’Intosh published the description of a ‘remarkable branched syllids,’ Syllis ramosa, during which collected Challenger-Expedition, one of the most important natural history expeditions of the 19th century,” explains the first author from the University of Göttingen Professor M. Teresa Aguado and colleagues.

“The worms were found in the hexactinellid sponge Crateromorpha meyeri at 175 m depth near Cebu in the Philippines.”

“Regarding their side branches, McIntosh said, ‘The body of the annelid seems to have a rage for budding laterally, terminally, and wherever a broken surface occurs. which represented the first example of an annelid species described with a randomly branched asymmetric body.”

“The second known type of branching, Ramisyllis multicaudata, was described in 2012 from the shallows off the coast of Darwin, northern Australia.”

“This study revealed striking differences in biology and morphology between this species and Syllis ramosa and analyzed its phylogenetic relationships within the family Sylliden.“

Ramisyllis multicaudata informs Syllis ramosa however, a randomly branching asymmetric body and its way of life in the labyrinthine internal channels of sponges differs (with the exception of the 2005 Sagami Bay reports on the Red Sea and Imajima). Syllis ramosa) in the host sponge (Petrosia vs. Crateromorpha), depth (0–20 m vs. 100–1,000 m deep) and important morphological and anatomical details.”

The home of the branching worm Ramisyllis Kingghidorahi: the host sponge Petrosia sp. in its natural habitat; The rear end of the branching worm can be seen on the surface of the sponge. Credit: Toru Miura.

The newly described species belongs to the genus Ramisyllis and inhabits the coastal waters of Sado-Insel, Japan.

His name, Ramisyllis Kingghidorahi, refers to King Ghidorah, Godzilla’s three-headed, two-tailed monster enemy.

“King Ghidorah is a branching fictional animal that can regenerate its lost ends, so we thought this was an appropriate name for the new breed of branching worms,” ​​said Professor Aguado.

“We were amazed to find another one of these bizarre creatures with just a head and a body made up of multiple branches,” she added.

“This discovery reveals a greater diversity of these arboreal animals than anyone expected.”

Professor Aguado and co-authors also hypothesized the evolution of branching body patterns as an adaptation to life in the labyrinthine canal system of their host sponges.

“The ability to produce new posterior segments throughout their lifespan (typical of many worms), together with their ability to regenerate and the worms’ ability to produce multiple newly formed segments simultaneously during reproduction, could lay the basis for the evolution of a branched body.” be,” they said.

“Scientists don’t yet understand the nature of the relationship between the branching worm and its host sponge,” Professor Aguado said.

“Is it a symbiotic relationship that benefits both creatures in some way? And how do the worms manage to feed themselves to maintain their huge bodies with only a tiny mouth in their single head?

the results were published in the journal Diversity and evolution of organisms.


MT Aguado et al. Ramisyllis Kingghidorahi n. sp., a new branched annelid from Japan. Org Divers Evol, published online January 22, 2022; doi: 10.1007/s13127-021-00538-4

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