New Jellyfish Species Discovered May Have an Arsenal of Unique Venoms


A new species of jellyfish has been discovered deep below the waves, and it may possess venoms that we have never seen before.

The new species, named Santjordia pagesi, was discovered at a depth of 2,664 feet near Japan’s Ogasawara Islands, floating around a deep-sea volcano known as the Sumisu Caldera.

The new jellyfish, which has been sighted only twice, is an umbrella-shaped medusa species, measuring around 4 inches across and with a red cross in the center of its body, according to a new paper in the journal Zootaxa. This inspired its common name: the St. George’s Cross Medusa.

A new jellyfish species is seen from above and the side (inset). Scientists named the jellyfish Santjordia pagesi because of its bright red stomach that resembles the Cross of St. George.

Dhugal John Lindsay/JAMSTEC

The jellyfish was captured from the depths and had its DNA analyzed, which revealed that it was so distantly related to all other species of jellyfish that scientists needed to designate not only a new species name but a whole new genus and subfamily.

“The species is very different from all the deep-sea medusae discovered to date. It’s relatively small, whereas others in this kind of environment are much larger,” paper co-author André Morandini, a professor of zoology and Director of the Center for Marine Biology at the University of São Paulo, said in a statement.

Because this new species is so evolutionarily different from other species that scientists have discovered, they suggest it may contain a cocktail of venoms drastically different in chemical makeup from anything previously seen.

“Who knows? Maybe it holds secrets more valuable than all the mineral wealth that could be extracted from that place. All this with the advantage of keeping the species and the site intact,” Morandini said.

The St. George’s Cross Medusa is mostly transparent, with the exception of its characteristic red cross marking, which is thought to make it harder for predators to spot any bioluminescent food the jellyfish has inside its belly.

“The bright red coloring of its stomach probably has to do with capturing food,” Morandini said.

A map show the location of the Sumisu Caldera (Smith Island) in the Ogasawara Islands, south of Japan.

The jellyfish was first spotted in 2002 during a research mission to the Sumisu Caldera using the remotely operated vehicle (ROV) Hyperdolphin, which captured the specimen and allowed for DNA analysis.

However, the species was not seen again until 2020, when it was filmed by the KM-ROV but evaded capture. It’s unusual for a new species to be confirmed after the collection of only a single specimen, as several of the animals are usually studied first. However, because of the apparent rarity of S. pagesi, it was designated a new species after a single specimen was captured and another observed.

new jellyfish capture
In 2002, a remotely operated submersible robot captured the specimen (bottom right) and images of the jellyfish. Only one specimen has ever been recovered.

Dhugal John Lindsay/Jamstec

The researchers hope that further expeditions to the deep-sea volcano will yield more sightings of the rare jellyfish.

“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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