Tag: Kei Chloe Tan

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New Research: A comparative molecular study of rhizostome jellyfishes from Japan reveals variability in Symbiodiniaceae taxon associations and cassiosome production.

Led by Kei Chloe Tan , this study dives deep into the complex world of Rhizostomeae that play massive roles in Asian ecology and industry.

What makes these jellies unique?

Rhizostome jellyfishes are unlike your average medusa. They don’t have long, trailing tentacles neither other structures at the eadg of theyr bell; they have eight highly branched oral arms, along which there are suctorial minimouth orifices.

Our study focused on three main goals:

  • Identity: Using DNA barcoding to accurately identify species in Japanese waters.
  • Partnership: Mapping which types of algae live inside which jellyfish.
  • The Sting: Identifying which species produce cassiosomes—the “mucus grenades” responsible for the mysterious “stinging water” syndrome.

Key Discoveries

  • A New Neighbor: We discovered that Cassiopea (Upside-down jellyfish) found in Kagoshima likely represents a new, undescribed species.
  • Symbiotic Flexibility: We found that these jellyfishes are “plastic” in their partnerships, meaning the same species of jellyfish can host different types of algae (Symbiodinium, Cladocopium, or Durusdinium) depending on the individual.
  • The “Grenade” Evolution: We confirmed that cassiosome production is a unique trait of the suborder Kolpophorae. Interestingly, we found that young jellies might not produce them until they reach a certain developmental stage.

“This research provides a baseline for understanding how jellyfish and algae co-evolve, helping us manage coastal ecosystems and the jellyfish fisheries that are so vital to the region.” — Chloe Tan, Lead Author

Lab Work in Action

This paper wasn’t just about sequences; it combined advanced molecular techniques with classic microscopy.

  • Tandem DNA Amplification: Chloe developed a new method to simultaneously sequence the DNA of both the jellyfish host and its tiny algal residents.
  • Microscopy: We captured high-resolution images of the cassiosomes—clusters of stinging cells (nematocysts) with algae at their core—proving exactly how these “contactless stings” work.

Read the Full Paper

Interested in the molecular data or the high-resolution phylogenetic trees? You can find the full study here:

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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。

[彩恵りり氏による解説記事はこちら]

[当研究室のオリジナル論文はこちら]

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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。

Find the original material at:

Find the original scientific paper here:

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New jellyfish species “Mikazuki no Eboshi” first confirmed in Tohoku

tank

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

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NHK – Coverage – Tohoku University research group names new species after Date Masamune

NHK broadcast the findings of our laboratory. We are exceptionally proud of our team’s achievement and delighted by the public interest generated by our research.

The broadcast provided a concise overview of the discovery and the underlying shift in marine currents that led the specimens to be washed ashore in Sendai Bay.

As Professor Ames stated:

“The discovery of this new species was incredibly exciting and a fortunate find, but it also serves as an indicator that the species is migrating north due to climate change.”

You can access the full NHK coverage and video on their website by clicking the icon below:

And you can find the complete scientific paper here:

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A new species of Portuguese man-of-war discoverd for the first time in the tohoku region – Named “Mikazuki no Eboshi” after Date Masamune

Mikazuki no Ebochi

2025 | Press Releases and Research Results

Tohoku University just released a press release show casing the most recent lab discovery at Sendai Bay. The before-mentioned “Mikazuki no Eboshi”

The emergence of this species may be related to changes in the marine environment caused by climate change, such as the northward shift of the Kuroshio Current and rising sea temperatures. The northward movement of poisonous species not only changes the ecosystem, but also requires caution when swimming in the sea.

This is the first record of the Portuguese man-of-war genus in the Tohoku region. Furthermore, particle tracking simulations revealed that the northward shift of the Kuroshio Current and rising sea temperatures may be related to the emergence of this species. The observation of the Mikazuki no Eboshi provides important evidence that climate change is affecting the distribution of marine life.

You can find the Scientific paper here:

You can find the full press relese here:

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New Discoveries Rock the Tank: Enoshima Aquarium Faces a Classification Dilemma

Enoshima Aquarium

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:

Enoshima Aquarium

Find our lab mentioned sicentific paper here:

Find the other relevant sientific paper here:

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This Gorgeous but Dangerous Jellyfish Was Just Discovered off Japan’s Coast

scitechdaily
Researchers in Japan Discover New Jellyfish Species Deserving of a Samurai Warrior Name

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:

  1. 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.
  2. 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.
  3. 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

Find the sicentific paper here: