What is the “glass octopus”, this rare animal filmed in the depths of the Pacific Ocean? – West-France evening edition

At more than 650 meters below the surface of the Pacific Ocean, scientists were able to film a rare species of octopus. Almost completely transparent, the “glass” animal has adapted its body to the extreme conditions of depth.

A new territory has been identified as the living environment of this octopus, in the depths of the Phoenix Islands, in the Kiribati archipelago, in the middle of the Pacific. (Map: Ouest-France)

Scientists announced on July 8, 2021 that they had succeeded in filming two specimens of a rare species of octopus. A great feat since the animal is almost completely transparent!

Named Vitreledonella richardi according to researchers, this “glass octopus” lives between 200 and 3,000 meters deep, in the waters of the Phoenix Islands, an archipelago of Kiribati, in the Pacific Ocean.

If the species is studied using specimens that have died since 1918, these images are the most precise ever taken in a natural environment. It was at the end of a 34-day expedition with the submarine SuBastian that the Schmidt Ocean Institute, an American foundation, announced that it had captured these moments of grace.

The animal was filmed at a depth of 651 meters.

A fascinating spectacle in a new distribution area

This video is an opportunity to see this animal evolve in its natural environment and to identify an additional distribution area. Biologist Laure Bonnaud-Ponticelli, professor at the National Museum of Natural History, in Paris, brings to the evening edition his lighting specialist in the evolution and development of cephalopod molluscs, that is to say whose body is provided with a crown of tentacles.

In addition to the fascinating spectacle, she points out that “The images show the stomach contents of glass octopuses. We therefore know what she ate and retrace her journey “.

The yellow color that we see in the digestive system is “Probably due to the carotenoid [un pigment végétal à l’origine des couleurs d’algues, de fruits ou de légumes, NdlR] present in phytoplankton “.

The latter, evolving on the surface, were first absorbed by other species to be released in small residues, until they reached the octopuses observed. “This is how we can see the food chain, even in the abyss”, notes the researcher.

Biologists are delighted to have identified “Changes in species depending on depth and topography” of the regions studied on this expedition, Dr. Tim Shank, a biologist at the Woods Hole Oceanographic Institute, United States, said in a statement from the Schmidt Ocean Institute.

“Examining these groups of organisms that live in the depths has changed the way we think about how they live and interact,” he added.

A rare and precious animal

“There aren’t many people who have been able to observe them yet., emphasizes Laure Bonnaud-Ponticelli. Their study was mainly done on dead animals, recovered from the digestive system of other animals, or with other underwater catches, brought up in poor conditions for their preservation. “

The shots are all the more precious as the animal is very fragile and the images difficult to obtain at such a depth.

Some cephalopods are adapted to great depths. The glass octopus withstands extreme conditions thanks to its “Organism lightened to the maximum and its metabolism slowed down to consume as little as possible of nutrients and oxygen which are scarce in abyssal waters”, emphasizes the professor. She adds that the cephalopod is able to live in water between 2 and 4 ° C.

This octopus’s digestive tract and gills are visible through its almost completely transparent body. (Screen capture: Schmidt Ocean Institute)

Its amplitude of 45 cm including its eight arms is reduced to 15 cm at the level of the part which contains all the organs, called the mantle. “It is the name given to the part of the body that one can imagine by bending forward and joining his feet and hands”, emphasizes Laure Bonnaud-Ponticelli.

Transparency, a survival strategy

This species has reduced its muscle mass so much that it has become transparent. At this depth, the number of chromatophores, these pigmented cells that help give color to the skin of animals or humans, is very limited.

The transparency of the body makes it possible in particular to escape predators.

“On this magnificent animal, in addition to the chromatophores, what is fascinating is that we can see the eyes, the gills and the digestive gland. “ The researcher also notes that this digestive tract is longitudinal. This allows, when predators are below or above the octopus, to only show a point, reducing its vulnerability. On the other hand, the danger is greater when an animal is on its sides. “The octopus then just has to swim fast. “

For its movements and its evolution in the water, this octopus plays on buoyancy. The lightness effect allows it to stay deep, in the water columns. The animal stores so little oxygen that there is no risk of rising to the surface. It describes a simple mechanism: “The cephalopod has a membrane between its arms, and the more we increase the surface of this parachute, the more we increase the resistance to the movements of the water and the less the animal falls to the bottom”. Due to its weak musculature, however, its ability to move is very limited.

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