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Unknown "Sea Monster" with 20 arms discovered in the dark Antarctic waters

In the depths of the frozen Antarctic sea, a team of intrepid scientists aboard a research vessel made an astonishing discovery. Within the pitch-black waters, the experts encountered a creature that seems to defy imagination. It is a previously unknown sea monster with a whopping 20 arms and a body that, curiously enough, bears a slight resemblance to a strawberry.

Antarctic feather stars 

The scientific expeditions, which spanned almost a decade from 2008 to 2017, were focused on a specific target: the pursuit of elusive or cryptic sea dwellers belonging to the genus Promachocrinus. These creatures are commonly known as Antarctic feather stars. 

While they may share some traits with other invertebrates such as starfish and sea cucumbers, the feather stars distinguish themselves through their considerable size and a somewhat ethereal presence when in motion.

“Although similar to other invertebrate ocean animals, like starfish and sea cucumbers, feather stars are distinct both in their ‘large’ size and ‘otherworldly appearance’ when swimming,” said the researchers.

Eight different species identified 

These marine anomalies have been found to inhabit depths ranging from 65 feet to an astounding 6,500 feet beneath the waves. The team identified eight singular species, half of which had never been previously described or named by the scientific community.

For years, specimens retrieved from earlier expeditions were suspected, though not confirmed, to belong to this group. Until the recent discoveries, the Promachocrinus kerguelensis was the sole species unmistakably identified as a member of this genus.

Scientific breakthrough 

However, the researchers highlighted a significant breakthrough that made these recent classifications possible: “The scholars noted that their capacity to aptly classify numerous additional distinct members within the genus had only now become possible thanks to an examination of both DNA and physical morphology, or shape, of these organisms.”

Among their exciting discoveries is the Antarctic strawberry feather star (Promachocrinus fragarius), a creature that showcases a spectrum of colors, ranging from muted purplish hues to a more intense dark reddish shade.

Vast ocean of mystery 

Despite the revelations about the feather stars, vast swathes of the Antarctic waters remain largely uncharted, with potentially countless undiscovered species lurking beneath. 

“Comprehensive exploration will be indispensable to gaining even a basic understanding of the profusion of life within the Antarctic waters,” concluded the researchers. The study was recently published in the journal Invertebrate Systematics.

More about Promachocrinus

Promachocrinus, while perhaps not as popularly known as some of its marine contemporaries, offers a compelling look into the prehistoric marine world and the evolution of crinoids.

What is a Crinoid?

Before diving into the specifics of Promachocrinus, it’s essential to understand what crinoids are. Crinoids are marine animals belonging to the class Crinoidea within the phylum Echinodermata.

They are commonly referred to as “sea lilies” or “feather stars”, depending on their mode of life. While sea lilies are sessile and attached to the ocean floor by stalks, feather stars are free-living.

Crinoids have been a part of the marine ecosystem for hundreds of millions of years, making their first appearance in the fossil record during the Ordovician period.

Promachocrinus: An overview

Promachocrinus is a genus within the crinoid class. Like other crinoids, it would have featured a central body (or calyx) from which extended numerous arms used for feeding. It lived during a time when the seas teemed with an array of fascinating and diverse life forms.

As mentioned above, scientists recently discovered a new species of Promachocrinus, Antarctic strawberry feather star (Promachocrinus fragarius)

Promachocrinus morphology

Promachocrinus, as with many of its kin, had a radial symmetry, a characteristic feature of echinoderms. Feather-like arms, which could be tens of centimeters long, would have crowned its body. These arms contained pinnules, smaller lateral extensions, which increased the surface area for catching food.

The central disc or calyx housed the creature’s internal organs. Below it, a stem or stalk may have anchored the animal to the seabed in some species. Stacked columnals composed this stalk, and people often find them as isolated fossils today.

Ecology and lifestyle

Like other crinoids, Promachocrinus was a filter feeder. It captured tiny particles of food from the water using its feathery arms. The arms moved food particles towards the mouth, located at the center of the calyx.

Depending on the species and time period, Promachocrinus could have been either sessile or free-moving. The sessile varieties, with their long stalks, would remain rooted to a spot. The more mobile varieties would move around the ocean floor.

Significance in the fossil record

Promachocrinus, along with other crinoids, is of great interest to paleontologists for several reasons:

Diversity and evolution

The numerous species of crinoids, including Promachocrinus, that have existed over the eons show a broad diversity. Studying them can shed light on evolutionary pathways and responses to environmental changes.

Paleoenvironment indicators

The presence of crinoid fossils, like Promachocrinus, can provide clues about ancient marine environments. For instance, their depth preferences can indicate past sea levels and water conditions.

Exceptional preservation of Promachocrinus

Crinoids often exhibit exceptional preservation in the fossil record, sometimes even showing soft-tissue details. This allows scientists to get a comprehensive look at the organism’s morphology.

Promachocrinus, while just one genus in the vast world of crinoids, is a testament to the resilience and adaptability of marine life. These ancient sea dwellers, with their delicate, feathery arms, give us a window into marine ecosystems of the past. In addition, they help scientists decipher the story of life on Earth.

As we continue to discover and study more fossils, the tale of creatures like Promachocrinus continues to unfold, enriching our understanding of the natural world.

More about sea monsters

Sea monsters have been a source of fascination, myth, and legend for centuries. They have captivated the imaginations of seafarers, storytellers, and explorers alike.

These tales, often born from genuine encounters with unfamiliar marine creatures, have been interwoven with cultural lore, feeding human curiosity about the unknown depths of the ocean. Here’s a dive into the topic of sea monsters:

Historical sea monsters


Ancient Near Eastern and Judaic texts describe the Leviathan as a giant sea serpent or dragon. They represent chaos and the untamed ocean.


In Scandinavian folklore, the Kraken is a massive octopus or squid-like creature that drags ships under the water to terrorize them.

Mermaids and mermen

These half-human, half-fish creatures have appeared in folklore across various cultures. They’re often depicted as beautiful. However, they can also portray themselves as treacherous beings that lure sailors to their doom.

Sea serpents

People have reported sightings of these elongated creatures around the world. People often describe them as giant, snake-like creatures, occasionally with humps.

Scientific explanations

Giant squid

Once believed to be pure legend, the giant squid (Architeuthis) is now a recognized deep-sea species. Many believe it to be the real-life basis for Kraken stories.


This long, slender, silvery fish, which can reach lengths of up to 36 feet, may be responsible for some sea serpent legends.


Some people could have exaggerated sea monster tales from encounters with unfamiliar species of whales.


Prehistoric marine animals, such as the Megalodon, a giant shark, might have inspired stories passed down through generations.

Modern sightings and hoaxes

Loch Ness Monster

While not a sea creature, this alleged lake monster, nicknamed “Nessie,” has made headlines worldwide with sightings, photos, and even sonar readings, though conclusive evidence remains elusive.

New Jersey’s Chessie

Like Nessie, there have been numerous reports of a serpent-like creature in the Chesapeake Bay.


There have been many hoaxes, especially during the 19th and early 20th centuries, with people claiming to have found remains or captured photographs of sea monsters.

Literature and pop culture

Sea monsters have a rich presence in literature, from ancient texts to modern novels and films. From Herman Melville’s “Moby Dick” to the monstrous creatures in Jules Verne’s “20,000 Leagues Under the Sea,” these entities have been used to embody the mysterious and often perilous nature of the deep blue.

Promachocrinus fragarius image credit Greg Rouse


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