A dark red creature, without stinging tentacles but with fleshy arms that extend like theater curtains, sailing silently in the absolute darkness. This, which can be quite scary, This is exactly what a scientific expedition has found in the Argentine Sea: a specimen of Stygiomedusa giganteaa jellyfish which has surprised by its large size when compared to that of a school bus.
Hard to see. The Stygiomedusa gigantea It does not receive the nickname “ghost jellyfish” on a whim, since, despite its large size, the truth is that It is very difficult to find because of how elusive it is. To give us an idea, since the first specimen was described in 1910, hardly any have been officially recorded. about 130 sightings throughout the planet for more than a century.
This makes this sighting that was made by the expedition ‘Lives in extremes‘ be really striking, although what has mattered is the quality and detail of the data obtained.
How it was done. The scientific team, aboard the R/V Falkor research vessel, used the SuBastian ROVa remotely operated vehicle capable of descending to abyssal depths and transmitting 4K video. It was this robot that captured the jellyfish on the Argentine continental slope that has left many with their mouths open.
The images point to a huge size of 11 meters when it has its ‘arms’ extended, which makes it comparable to a school bus. But also, unlike other jellyfish, the Stygiomedusa It does not sting, since it does not have poisonous tentacles. What it does have are four massive oral arms that it uses to catch prey and bring it to its mouth.
Its color. Its reddish-brownish tone makes it practically invisible in the depths, where the red light of the solar spectrum is the first to be absorbed by water. To the eyes of other deep-sea animals, this jellyfish is effectively black and invisible, which makes it very easy to find food.
Beyond the jellyfish. Although it has received practically all the attention due to its large size, the true scientific “treasure” of the expedition could be on the seabed. And the researchers from CONICET and the University of Buenos Aires were not only looking for pelagic fauna, but They wanted to map and study the underwater canyons, like the Colorado-Rawson canyon.
And there, the SuBastian ROV’s sonar and cameras found something unexpected: the largest cold-water coral reef known to date in the region.
Its characteristics. It is nothing less, since we are talking about an ecosystem dominated by the species Bathelia candida, a scleractinian coral that forms complex three-dimensional structures. The data indicates that one of its patches covers 0.4 square kilometers and extends the known distribution range for this species some 600 kilometers to the south.
This is a vital discovery, because this coral acts as an “ecosystem engineer”, providing shelter, breeding and feeding grounds for an immense variety of fauna, including fish of commercial interest.
Use of technology. The ship that has given rise to all these discoveries has traveled more than 3,000 kilometers from Buenos Aires to Tierra del Fuego, carrying out a systematic sweep of the ocean floor. To do this, they have used robots like the SuBastian, which allows marine biologists to do something that traditional trawl nets could not: observe the behavior of species in their natural habitat without harming them.
This type of mission reminds us of a recurring maxim in modern oceanography: we know better the surface of Mars than the bottom of our own oceans. Finds like this giant jellyfish or new coral reefs are not just curiosities; They are key pieces to understanding how to protect biodiversity in a rapidly changing ocean.
Images | Schmidt Ocean Institute
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