New jellyfish discovered near Japan may contain multitudes of venom

A team of Japanese and Brazilian scientists have discovered a funky new jellyfish with a distinctive marking. The jellyfish of the St. George's cross (Santjordia pages Or S. pagesi) is a new species of jellyfish found approximately 2,664 feet deep in the Pacific Ocean. It lives in a deep volcanic structure called the Sumisu Caldera. This hot, active hydrothermal caldera is approximately six miles in diameter and is located off the coast of Japan's Ogasawara Islands, approximately 285 miles south of the capital Tokyo. The results are described in a study published in November in the journal Zootaxa.

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Protect your snacks – with a shield and 240 tentacles

The St. George's Cross jellyfish is considered quite large for a jellyfish, measuring approximately four inches wide and three inches long. He also boasts about 240 tentacles. It gets its name from the cross-like shape on its body when viewed from above, which resembles red. Cross of St. George on the English flag.

This is a type of jellyfish called jellyfish (or plural, jellyfish), which are free-swimming, umbrella-shaped jellyfish with a reduced stem.

“The species is very different from any deep-sea jellyfish discovered to date. It is relatively small, while others in this type of environment are much larger. The bright red color of its stomach is probably linked to capturing food,” André Morandini, co-author of the study and a biologist at the University of São Paulo in Brazil, said in a statement.

The St. George's cross jellyfish swims by pulsing its body. CREDIT: Japan Agency for Marine and Terrestrial Science and Technology

Like all jellyfish, S. pagesi is transparent. It also eats other deep-sea bioluminescent organisms that emit light. The team believes its bright red stomach acts as a shield to hide its prey. This way, other organisms cannot see its meal once it has swallowed it.

A rare find

While new species are constantly being discovered and described, this one was particularly rare. It was so difficult for the team to collect that the results are based on a single specimen. However, the team reportedly saw another S. pagesi nearby and we expect future surveys to show more members of the group.

A Santjordia pagesi, or the St. George's cross jellyfish, swimming in its natural habitat. CREDIT: Lindsay et. 2023.

The study specimen was captured in 2002 by the remotely operated vehicle (ROV) Hyperdolphin. The Sumisu Caldera is only accessible via ROV because it is very deep. Scientists did not see any other specimens until 2020. ROVs filmed, but did not collect, another jellyfish of the same species.

[Related: These fingernail-sized jellyfish can regenerate tentacles—but how?]

“We chose to publish the description and draw attention to the species present at the site, which has mineral-rich substrate and potential for commercial development. Unfortunately, research cannot be conducted in such places without partners with interests of this type,” Morandini said.

“Arsenal of venom”

S. pagesi belongs to a new subfamily named Santjordiinae. It has small sensory structures called rhopalia underneath and around the edges of its umbrella, making it unique among the order's jellyfish. Semeostomes. It is to this order that the most common species such as moon jellyfish belong. The team believes it could eventually become part of the Semaeostomeae when they can collect more species. For now, it remains among the Ulmaridae, the larger jellyfish family.

Because it is so different among jellyfish, the authors believe it potentially has a different “arsenal of venoms” than those previously discovered in jellyfish. The Indo-Pacific box jellyfish releases a venom that makes the heart contract and Australian box jellyfish can release this venom from thick tentacles up to 10 feet long.

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

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