カツオノエボシは1種ではなかった：5種への再分類と新種「ミカヅキノエボシ」の命名 執筆：彩恵 りり
サイエンスライターの彩恵りり氏が、カツオノエボシ属（Physalia属）が5種に再分類された最新の研究について詳しく解説してくださいました。これら新種のうち1種の発見に当研究室が貢献したことを、大変光栄に思います。
Mikazuki no Eboshi as one of the 14 New and Unusual Species of 2025 by Discover
Alongside 13 other new species is our lab’s discovery, the Mikazuki no Eboshi (Physalia mikazuki).
These other new species are also incredibly interesting discoveries, spanning a wide range of habitats and phyla. Each has truly unique characteristics and is well worth a look.
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Find the original scientific paper of our discovery here:
Nikkei reported on Mikazuki no Eboshi: 宮城県で新種のクラゲ、伊達政宗にちなんで命名 東北大学
Our lab’s discovery was featured in a Nikkei article. The piece focused on the computer simulation used to estimate the period and travel path of the specimen, as it originated from a different region than the discovery site:
コンピューターを使ったシミュレーション（模擬実験）の結果、神奈川県沖の相模湾などから海流に乗って運ばれた可能性があると分かった。研究成果をまとめた論文は学術誌「フロンティアズ・オブ・マリン・サイエンス」に掲載された。
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New jellyfish species “Mikazuki no Eboshi” first confirmed in Tohoku
By: 官庁通信デジタル _ KANCHO TSUSHIN DIGITAL
A group led by Professor Cheryl Ames of Tohoku University has discovered a new species of jellyfish, the “Mikazuki no Eboshi” This is the first time that a highly venomous species of jellyfish, a relative of the Portuguese man-of-war, has been found in Tohoku. They analyze that one of the reasons for its discovery is the abnormal fluctuations in ocean conditions in recent years.
The Portuguese man-of-war lives in tropical and temperate climates. In Japan, it is found from Okinawa to Sagami Bay, but has not been officially confirmed along Japan’s northern coast until now. The crescent-shaped crest of the helmet worn by Date Masamune, a military commander active in the Tohoku region, is the origin of the name.
The Mikazuki fish was collected after being washed up on Gamo Beach in Sendai City, Miyagi Prefecture. It is speculated that the northward movement of the Kuroshio Current carried this species, which lives in southern Japan, to Tohoku. Ocean current simulations suggest that it takes about 30 days for the fish to travel from Sagami Bay to Sendai Bay, and 45 days to reach the coast of Aomori.
The group commented that “this study provides important insights into understanding the movement and dispersal of marine organisms due to climate change,” and added, “Changes in the appearance and distribution of jellyfish have the potential to affect not only ecosystems but also people’s lives and safety, so we need to carefully monitor their trends.”
Find the original material at: 官庁通信デジタル
Find the original scientific paper here
New Discoveries Rock the Tank: Enoshima Aquarium Faces a Classification Dilemma
Discover the immediate dilemmas facing the Enoshima Aquarium—and what this means for their highly successful Portuguese Man-of-War exhibit.
Following the big splash made by the scientific discoveries originating from our lab, the established understanding of Physalia (the Portuguese Man-of-War) has been revolutionized. Research, which included the recent identification of Physalia mikazuki by our lab, now shows that what was once thought to be a single species first expanded to four and, with our lab’s subsequent discovery, grew to five distinct species in just over three months.
Opening what promises to be an amazing series in the Enoshima Aquarium Trainer’s Journal, Trainer Yamamoto presents a critical series of questions that highlight the practical impact of new taxonomy:
“Will we need to change the scientific names listed on our fish display boards and exhibits? Which species does the Japanese common name ‘Katsuo-no-Eboshi’ actually refer to? Since it is famous as a ‘highly venomous creature,’ are all five species equally dangerous?”
We are closely monitoring the developments at the Enoshima Aquarium and anxiously awaiting the answers to their questions.
It’s amazing to see the far-reaching impact of new and relevant scientific discoveries. You can find the full original post in the Enoshima Aquarium Trainer’s Journal here:
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This Gorgeous but Dangerous Jellyfish Was Just Discovered off Japan’s Coast
New, Venomous Portuguese Man-of-War Discovered in Japan’s North: Physalia mikazuki
This new species, named Physalia mikazuki (“crescent helmet man-o-war”) in honor of the samurai lord Date Masamune, marks the northernmost recorded presence of the Physalia genus to date, with specimens collected off the coast of northeastern Japan (Sendai Bay).
A student-led research team at Tohoku University (greatly formed by our lab) has formally identified a previously unknown species of the venomous siphonophore, Physalia —commonly known as the Portuguese man-of-war.
Key Scientific Findings:
- New Species Identification: Through detailed morphological examination and genetic analysis, the team confirmed that P. mikazuki is genetically distinct from its tropical relatives, specifically Physalia utriculus, which was previously believed to be the only species of the genus inhabiting Japanese waters.
- Climate-Driven Range Extension: The appearance of P. mikazuki in the colder waters of the Tohoku region suggests a significant shift in marine distribution. Ocean surface current simulations confirmed that the northward extension of the Kuroshio Current, combined with unusually high sea-surface temperatures, likely transported the colonies to Sendai Bay.
- Ecological Significance: The discovery provides direct evidence that climate-related changes in ocean circulation are actively reshaping the distribution of marine species, highlighting the urgency of coastal observation.
The research not only adds a new species to the world’s taxonomic records but also underscores the immediate impact of climate change on ocean ecosystems, influencing where even dangerous marine life can drift and thrive.
Find the original storye at SciTechDaily.com
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New Jellyfish Discovery in Japan Is So Weird It Had to Be Named After a Samurai
In a rare marine encounter, researchers in Japan have uncovered a previously unidentified species of Portuguese man-of-war, Physalia mikazuki, off the coast of northeastern Japan. This marks the first time such a venomous jellyfish has been documented so far north in the country, with experts tying its arrival to warmer waters and changing currents.
access the complete story on the IDR(indian defence review) website
Find the original scientific paper here
New Portuguese Man O’ War Species Discovered After Warming Ocean Currents Push It North
A new species of Portuguese man o’ war has been discovered floating in the waters of northeast Japan. Spotted by a student-led research group, the discovery marks a species that has never been seen before in the area, raising questions about shifting distributions of marine creatures due to the effects of climate change.
The lab work is making a big impact in the media. We are proud to display the media coverage here and you can access the complete story on the IFLScience website.
Find the full paper here
Media Spotlight: New Samurai-Named Jellyfish Highlights Climate Change Threat
Our recent research paper, detailing the discovery of a new venomous jellyfish species in Japan, has captured international media attention, with outlets highlighting the fascinating cultural connection of its name and its critical implications for marine science.
The discovery, published in Frontiers in Marine Science, confirms the existence of Physalia mikazuki sp. nov.—a new type of Portuguese Man-of-War found unexpectedly far north in Japan’s Tohoku region.
A Name Worthy of a Warrior
The media coverage, including articles from Tohoku University, Asia Research News, and ScienceDaily, emphasized the unique story behind the new species’ name. The jellyfish was named P. mikazuki (“crescent helmet man-o-war”) as an homage to the legendary samurai warrior and feudal lord of Sendai, Date Masamune, who was famous for the crescent moon (mikazuki) adorning his helmet.
This culturally significant name drew attention to a serious scientific finding: the species’ arrival in the temperate Tohoku region is a direct result of marine ecosystem change.
Climate Change Drives Species North
The research, led by a team including Cheryl Lewis Ames, Chanikarn Yongstar, Kei Chloe Tan, and Ayane Totsu, suggests that warming coastal waters and the northward shift of the Kuroshio Current are pushing tropical species into previously untouched temperate zones. The study used DNA analysis and particle simulation modeling (as highlighted by the coverage) to confirm the species is distinct and to track its probable drift path from warmer waters.
This finding serves as a powerful indicator of how climate change is rapidly altering the global distribution of marine organisms, necessitating increased monitoring to ensure coastal safety and ecological understanding.
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Tohoku Univ. first candidate for huge Japan gov’t research grants
The national university in the northeastern Japan prefecture of Miyagi is set to be formally selected as early as fiscal 2024 as a recipient of annual financial support for up to 25 years from fiscal 2024, starting with around 10 billion yen ($69 million) in the initial year.
Under the new Universities for International Research Excellence program, the grants will be paid out of profits generated from a 10 trillion yen fund.
Tohoku University has been rated highly for its large number of research paper citations, and measures to strengthen its research capabilities and reform its management, the ministry said.
Live Jellyfish Make a Splash in Marine Education
The Smithsonian Magazine that takes you behind the scenes at the National Museum of Natural History! The piece shines a spotlight on the museum’s unique “AquaRoom” a dedicated facility where live jellyfish and other marine invertebrates are raised and studied.
The AquaRoom, co-founded by marine biologists Allen Collins and Dr. Cheryl Ames, had humble beginnings but a grand vision. As Allen Collins recounts,
“So, Cheryl and I started collecting freebie aquarium stuff that people were getting rid of in the department, including a 55-gallon tank.”
From these dedicated efforts, the facility grew to cultivate various jellyfish species and became instrumental in educational outreach, offering tours, bringing live jellyfish to the museum floor, and continuing its mission through virtual webinars and collaborations, even sending jellyfish polyps for student experiments.
Who’s in this Ocean? Tracking Down Species on the Go Using Environmental DNA
The article details the development of a novel method for tracking marine species: the portable eDNA sequencing kit (FeDS), spearheaded by Dr. Cheryl Lewis Ames’s team from Tohoku University. The article explains how the FeDS kit makes the complex process of environmental DNA identification — from water sample collection to species identification — entirely portable and capable of being conducted on-site without an internet connection, thanks to the Nanopore MinION device.
The effectiveness of the FeDS kit was successfully tested in the Florida Keys, where the team not only detected the upside-down jellyfish (Cassiopea) but also identified a remarkable 53 jellyfish species, including two venomous box jellyfish species previously unreported in the area. Dr. Ames envisions incredible practical applications for this technology, such as predicting jellyfish sting risks, much like a ‘weather forecast app’ for swimmers!
This innovative research was published in the esteemed Frontiers in Marine Science journal, underscoring its solid impact and global relevance.
And to access the original scientific paper that underpins this research, click here:
Tracking Down Ocean Species On the Go Using eDNA
The article highlights the pioneering work of our own Dr. Cheryl Ames and her team in the Florida Keys. They led a crucial study demonstrating the potential of a portable Nanopore sequencer to detect the presence of upside-down jellyfish (Cassiopea xamachana) and other jellyfish species directly in the field! This represents an incredible leap forward, overcoming the challenges of bringing complex DNA analysis from labs into the marine environment.
This technology not only identified Cassiopea jellyfish but also revealed the presence of other species unseen at the time of sampling, such as moon jellyfish and venomous box jellyfish. The potential is vast: from predicting jellyfish sting risks to aiding fisheries management, supporting conservation efforts, and even integrating into autonomous underwater vehicles for comprehensive marine surveys.
This groundbreaking research stems from a foundational scientific paper published in Frontiers in Marine Science, underscoring its impact.
Read the full article on Smithsonian Ocean and dive into the future of species detection:
And for the original scientific paper that underpins this amazing work, access it here:
These jellyfish can sting without touching you, thanks to ‘mucus grenades’
Imagine encountering a creature that defends itself with unseen projectiles! National Geographic invites you on a journey into the remarkable world of upside-down jellyfish, showcasing Dr. Cheryl Ames’s extraordinary research into their unique defense strategy.
This captivating feature explores how these intriguing invertebrates, Cassiopea spp., can release ‘mucus grenades’ – microscopic, venom-filled structures that pack a potent sting without direct contact. Dr. Cheryl Ames, a marine biologist and associate professor at Tohoku University, provides a fascinating glimpse into the observation of these creatures’ efficiency:
“Then, within 24 hours, the pink cloud will be gone.” (referring to the cloud of zapped brine shrimp after feeding). This observation speaks volumes about the efficacy of their hidden defense system.
National Geographic beautifully illustrates how Dr. Ames’s profound contributions are reshaping our understanding of marine ecosystems and the intricate adaptations within them. It’s truly inspiring to see this deep dive into nature’s secrets featured by such a world-renowned publication, bringing the wonders of the ocean floor to life for millions worldwide.
Upside-down jellyfish release venom-filled ‘bombs’ in their snot
Mucus produced by these upside-down jellyfish can be seen floating above their frilly arms. (Image credit: Allen Collins and Cheryl Ames) For years, swimmers have felt a perplexing tingling in waters inhabited by upside-down jellyfish, even without direct contact. Now, Live Science delivers the definitive scientific explanation, thanks to the pivotal research co-led by Dr. Cheryl Ames!
The long-standing question of what causes this ‘stinging water sensation’ has finally been addressed. As Dr. Cheryl Ames, an associate professor of applied marine biology at Tohoku University, explains the initial scientific challenge:
“We knew it had to be something in the mucus.”
Her team’s methodical investigation led to the identification of ‘cassiosomes’ – microscopic, venom-filled structures released by the jellyfish – providing the clear answer.
This compelling Live Science article details the journey of scientific inquiry, highlighting the rigorous process that unveiled nature’s hidden mechanisms. We’re proud to see Dr. Ames’s dedication to solving marine mysteries recognized by Live Science, bringing clarity and understanding to a broader audience.
Upside-down Jellyfish Create ‘Stinging Water’ That Kills Prey by Launching Mucus ‘Grenades’
[This study] began when I and other marine biologists were concerned about the source of ‘stinging water’—an irritating sensation that occurred while in the mangrove forest waters studying upside-down jellyfish, and working together with aquarists at major public aquariums,” Cheryl Ames, an author of the study from Tohoku University, Japan, and the Smithsonian’s National Museum of Natural History, told Newsweek.
“There were several theories exchanged by fellow marine biologists, and comments posted online by people after experiencing stinging water during snorkeling or swimming in those areas. We wanted to find out the scientific explanation behind the long-standing stinging water puzzle,” she said.
Upside-Down Jellyfish Release Weaponized Goo Packed With Toxic ‘Grenades’
Cassisomes as seen through a microscope. The oval structures are laced with toxic capsules known as nematocysts, and the brown blobs are symbiotic algae that live within the tissues of Cassiopea. Image: (Cheryl Ames and Anna Klompen) Forget what you thought you knew about jellyfish! A recent mind-bending article on Gizmodo blasts open the bizarre secret of Cassiopea spp. – the upside-down jellyfish that can sting you without even a touch!
The mystery behind that infamous ‘stinging water’ has been cracked wide open, thanks to groundbreaking research co-led by Dr. Cheryl Ames. Her team discovered microscopic, venom-packed ‘cassiosomes’ that navigate on their own. As Dr. Ames vividly describes these tiny attackers:
“They were autonomous, moving around like little Roomba vacuums and bumping into the brine shrimp that we fed them, just killing them on contact, and moving on to the next.”
It’s truly wild to see Dr. Ames’s pioneering work not just uncovering new biological mechanisms but making such an incredible splash on Gizmodo, bringing truly cutting-edge, weird science to everyone!
Jellyfish Expert: Biodiversity & Genomics