A New Species of Jellyfish Discovered in Japan

Published by Cédric - Wednesday, February 14, 2024 - Other Languages: FR, DE, ES, PT
Article Author: Cédric DEPOND
Source: Zootaxa

A research team has described a novel species of jellyfish discovered in a remote location in Japan. This rare jellyfish was found at a depth of 2,664 feet (812 meters) within an underwater volcanic structure known as the Sumisu caldera, in the Ogasawara islands. The gelatinous animal, about 4 inches (10 cm) in diameter and featuring a red stomach reminiscent of the St. George's Cross viewed from above, has been identified as Santjordia pagesi, a new species of jellyfish. It is a type of free-swimming umbrella-shaped jellyfish with a reduced peduncle.


André Morandini, the senior author of the paper, is a part of the research team. He is a professor of zoology at the Institute of Biosciences of the University of São Paulo (IB-USP) and director of the Center for Marine Biology (CEBIMar) of the same university. The other authors are researchers from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) in Japan, and from the Okinawa Institute of Science and Technology (OIST), also in Japan.

The St. George's Cross Jellyfish, as it has been named, appears to only live in the Sumisu caldera in the Ogasawara islands, approximately 286 miles (460 km) south of Tokyo. The caldera is an underwater hydrothermal volcanic structure with a diameter of about 6.2 miles (10 km) and a depth of 2,664 feet (812 meters). "This species is very different from all the deep-sea jellyfish discovered so far. It's relatively small, while others in such an environment are much larger. The bright red coloring of its stomach probably has to do with capturing food," explains André Morandini.

Like all jellyfish, S. pagesi is transparent, and the bright red stomach ensures that bioluminescent organisms cannot be seen by predators once swallowed. Bioluminescence (light emission by living organisms) is common in the darkness of the deep sea.


The species name, pagesi, was chosen in honor of Dr. Francesc Pagès, a jellyfish taxonomist from Barcelona, who passed away recently. The authors determined that the jellyfish belongs to a new genus (Santjordia, St. George in Catalan) and a subfamily (Santjordiinae) of the Ulmaridae jellyfish family.

The discovery of a new species usually involves collecting several specimens, but S. pagesi is very rare, and collecting it was so difficult that the description was based on a single specimen, although the scientists saw another specimen nearby and expect future deep-sea explorations to discover more members of the group. A previous specimen had been identified in 2002 by the remote-operated vehicle (ROV) Hyperdolphin during a dive in the Sumisu caldera, accessible only by scientific expeditions with such specialized equipment. No other specimens were found until 2020, when the KM-ROV filmed another individual of the same species.

"We decided to publish the description and highlight the species present at the site, which has a substrate rich in minerals with the potential for commercial exploitation," Morandini stated.

Due to its difference even from closely related species, the researchers believe that S. pagesi might also possess a different array of venoms from those discovered so far. "Who knows? Maybe it holds secrets more valuable than all the mineral wealth that could be extracted from this place. All of this with the advantage of keeping the species and the site intact," Morandini remarked.
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