Scientists have discovered a new species of medusa jellyfish living in the Sumisu Caldera, a volcanic formation in Japan.

They named it Santjordia pagesi because it resembles the Saint George's Cross.

New Species

It lives at a depth of more than 800 meters in the Sumisu Caldera in the Ogasawara Islands, about 460 kilometers south of Tokyo, and is a hydrothermally active deep-sea volcanic structure with a diameter of around 10 kilometers.

The jellyfish species is estimated to be approximately 10 cm in diameter.

"The species is very different from all the deep-sea medusa discovered to date. It's relatively small, whereas others in this kind of environment are much larger. The bright red coloring of its stomach probably has to do with capturing food," study co-author André Morandini from the University of São Paulo in Brazil said.

The St. George's Cross medusa is fairly large for a jellyfish, measuring around four inches broad by three inches long. It also has approximately 240 tentacles.

It receives its name from a cross form on its body that, when viewed from above, resembles the English flag's crimson cross of St. George. It is a free-swimming jellyfish known as a medusa (or medusae), which has a shortened stalk and resembles an umbrella.

At depths of roughly 812m in the sea, numerous organisms use bioluminescence to navigate in the dark.

Scientists believe that the new jellyfish's vivid red stomach keeps the bioluminescent prey it swallows hidden from other predators.

The S. pagesi belongs to a new subfamily called Santjordiinae.

It has microscopic sensory organs called rhopalia on the underside and edges of its umbrella, distinguishing it from other jellyfish in the Semaeostomeae order.

This is the order to which most common species, such as moon jellyfish, belong. The researchers believe it will eventually fit within Semaeostomeae after more species are collected. For the time being, it is classified as part of the Ulmaridae family of jellyfish.

Researchers discovered that the medusa differed significantly from closely similar recognized species and believe S. Pagesi may have venom that is substantially different from what has already been discovered.

Morandini emphasized that perhaps it contains knowledge more valuable than any mineral wealth that could be recovered from that location. All of this comes with the added benefit of preserving the species and the site.

An Extremely Rare Find

Usually the discovery of a new species necessitates the gathering of many specimens; however, since S. Pagesi is extremely rare and difficult to obtain; its description is based solely on a single specimen.

The team had such a tough time collecting that the findings are based on a single specimen. However, the team reportedly saw another S. pagesi nearby.

The study's specimen was collected in 2002 by the Hyperdolphin Remotely Operated Vehicle (ROV).

Because of its depth, the Sumisu Caldera can only be reached via ROV. Scientists did not find any additional specimens until 2020. An ROV filmed, but did not collect, another jellyfish of the same species.

Researchers expect that future studies of the deep ocean will help them identify more members of the species.

"We opted to publish the description and call attention to the species that are present at the site, which has a substrate rich in minerals and the potential to be commercially developed. Unfortunately, research can't be conducted in such places without partners who have interests of this kind," Morandini said.

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