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Very rare medusa jellyfish species spotted near Japan

In the vast and mysterious depths of the ocean, scientists have revealed a fascinating new species of medusa jellyfish, known as Santjordia pagesi, or the St George’s Cross Medusa.

This unique creature captivates with its gelatinous, umbrella-shaped body and a striking red stomach that resembles the Cross of St George when viewed from above.

Spanning about 10 cm in diameter, this medusa stands out for its vibrant coloration and diminutive size, especially when compared to other deep-sea jellyfish.

Finding the medusa jellyfish Santjordia pagesi

S. pagesi‘s home is the Sumisu Caldera in the Ogasawara Islands, a hydrothermally active deep-sea volcanic structure located about 460 km south of Tokyo.

This environment, known for its rich mineral substrate and potential for commercial development, has revealed a species that defies the common characteristics of deep-sea jellyfish.

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

Evolutionary adaptations: Survival in the deep

One of the most intriguing aspects of Santjordia pagesi is its transparency and the bright red stomach, which plays a crucial role in its survival.

This feature ensures that bioluminescent prey, common in the dark depths of the ocean, cannot be seen by predators once swallowed, providing a fascinating glimpse into the evolutionary adaptations of deep-sea life.

The naming of the species pays homage to Dr. Francesc Pagès, a renowned jellyfish taxonomist, further emphasizing the scientific community’s tradition of honoring its members’ contributions.

Medusa jellyfish Santjordia pagesi is rare and elusive

Additionally, the discovery process for S. pagesi was notably challenging due to its rarity.

The team relied on a single specimen captured in 2002 by a Remotely Operated Vehicle (ROV) Hyperdolphin, with another sighting in 2020, underscoring the difficulties of deep-sea exploration.

“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,” explained Morandini.

“Unfortunately, research can’t be conducted in such places without partners who have interests of this kind.”

Morandini’s insights also touch on the broader implications of such discoveries, pointing out the potential for Santjordia pagesi to possess unique venoms, distinct even from those of closely related species.

“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,” he speculated, highlighting the untapped potential of biodiversity over commercial exploitation.

International collaboration

The discovery of S. pagesi was a collaborative effort involving an international team of scientists, including André Morandini, a zoologist from the University of São Paulo’s Institute of Biosciences and Director of the Center for Marine Biology.

Morandini’s research was supported by FAPESP’s Research Program on Biodiversity Characterization, Conservation, Restoration, and Sustainable Use (BIOTA-FAPESP), highlighting the importance of international and interdisciplinary cooperation in marine biology.

In summary, this study expands our understanding of the rich tapestry of life in the deep sea while emphasizing the importance of preserving these environments.

As scientists continue to explore these uncharted territories, each new medusa jellyfish species discovery, like Santjordia pagesi, brings us closer to understanding the complex web of life that exists in the depths of our oceans, reminding us of the wonders that lie hidden beneath the waves and the need to protect them for future generations.

More about medusa jellyfish

As discussed above, medusa jellyfish, named after the mythical Greek monster with snakes for hair, captivate observers with their mesmerizing forms and graceful movements through the water.

These creatures, part of the larger jellyfish family, distinguish themselves with their bell-shaped bodies and trailing tentacles, embodying the quintessential image of a jellyfish.

Anatomy and characteristics

The anatomy of a medusa jellyfish is both simple and intricate. At the heart of their design is the bell or umbrella, capable of pulsating to propel the jellyfish through the water.

Hanging from the bell are tentacles equipped with cnidocytes, specialized cells that release venom to capture prey or deter predators.

This efficient predatory strategy highlights the medusa’s role as an adept hunter within its aquatic realm.

Habitat and distribution

Medusa jellyfish, like Santjordia pagesi, are not confined to any single marine environment but are found across the world’s oceans, from the shallows to the depths of the open sea.

Their adaptability allows them to thrive in a variety of conditions, including temperate, tropical, and even some freshwater ecosystems, showcasing their broad ecological range.

Life cycle and reproduction

The life cycle of medusa jellyfish includes two main stages: the sessile polyp stage and the free-swimming medusa stage.

This dual-phase life cycle allows them to exploit different ecological niches and contributes to their success as a species.

Reproduction can occur both sexually, with the medusa stage releasing sperm and eggs into the water, and asexually, with polyps budding off new individuals, ensuring their widespread presence in marine environments.

Ecological role and impact

Medusa jellyfish play a significant role in marine ecosystems, serving as both predator and prey.

Their diet mainly consists of small fish, zooplankton, and other jellyfish, positioning them as important regulators of marine population dynamics.

However, their capability to form large blooms can also have significant impacts on human activities, such as fishing and tourism, and on the overall health of marine ecosystems.

Conservation and study

The study of medusa jellyfish, like Santjordia pagesi, is crucial for understanding marine biodiversity and the health of oceanic ecosystems.

Researchers focus on their distribution, population dynamics, and ecological impacts to better manage and conserve marine environments.

The beauty and mystery of medusa jellyfish continue to inspire both scientific curiosity and a deeper appreciation for the complexity of life beneath the waves.

In summary, medusa jellyfish, with their elegant forms and ecological importance, remind us of the ocean’s vast mysteries and the need to protect its fragile ecosystems.

As symbols of the sea’s beauty and power, they challenge us to explore, understand, and ultimately safeguard the marine world for future generations.

The full study was published in the journal Zootaxa.


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