In the true or false junior, the students question us about the abyss, these depths of the seas that we have very little explored.
The abyss and the seabed fascinate as there is still so much to discover. Students from the Sacré-Coeur college in Marseille and those from Jules Ferry, in Essonne, ask us about the depths of the oceans and this is Olivier Lascar, editor-in-chief of the digital center of Science and the futurehe is the author of “Abyss, the final frontier”published by Alisio.
Yes, we’ve already been to the deepest point on Earth
Tino wonders if it’s true “that humans have managed to go to the deepest place in the abyss, that is to say 11,000 meters deep” and Clara wonders about the deepest abyss, “the Mariana Trench”.
Olivier Lascar agrees with them both, “the deepest point on the planet is at the level of the Mariana Trench, there is a point in particular, the ‘challenger deep’, which is approximately 11,000 meters deep and it is the deepest place on earth.“Olivier Lascar explains “that there are several explorers who have gone to a depth of 11,000 meters, the first, in 1960, were the Swiss Jacques Piccard and the American Don Walsh who reached the bottom of the Challenger trench aboard the bathyscaphe Trieste in 10,916 meters.”
For the anecdote, they were very scared, they said that during the dive, they heard, for an instant, a terrible crack, which came from the porthole. This created a moment of anxiety during the expedition, but in the end everything went well.
About 5% of the ocean floor has been explored
Chiara wonders if it’s true”that barely 2% of the ocean floor has been explored by underwater vehicles.”
According to Olivier Lascar, it would be around 5% maximum, but “this shows the immensity of the virgin territory which still remains to be defined”. He adds that we very often say “that we know the surface of the Moon better than that of the ocean floor.” This is a very difficult environment to access and Olivier Lascar explains to us that “the pressure there is very difficult to counter”. An explorer who did a lot of diving aboard a submarine called the Nautile told him that when you are at a depth of 4,000 meters, “It’s a bit like having the weight of a cow on every square inch of your skin.”
In mid-October, Ifremer, the French research institute dedicated to knowledge of the ocean, launched a new expedition to continue exploring the abyss, in the middle of the Atlantic, more than 3,500 meters above sea level. depth. There is also the project, Seabed 2030, responsible for mapping the entire ocean floor, a sort of global ultrasound, seen from above. Currently they are more than 20% mapped and their objective is to achieve 100% mapped areas by 2030.
There are millions of creatures left to discover in the abyss
Yasmine wonders if it is true that “In the abyss there are sea creatures that we still haven’t discovered.”
Olivier Lascar replies that we estimate that there is “250,000 marine species identified by scientists and there remain between one and 10 million to be discovered.” He states that most of the creatures that live in the abyss “are extremely small, the vast majority are invisible to the naked eye, there are also crustaceans, worms, and even cephalopods, that is to say a kind of octopus.”
These marine creatures that feed on “sea snow”
Bastien wonders if it is true that “In the abyss most marine animals are scavengers.”
Yes, it’s true, Olivier Lascar replies, “Most marine animals are scavengers because they feed on what is called sea snow, a kind of dust that falls from the surface and settles by gravity on the bottom of the water.“Olivier Lascar specifies that “this snow is made up of animals which have died and which decompose into small crumbs of their corpses, or it can also correspond to the droppings of animal species which live more on the surface.” All this material settles and falls to become the main food of the inhabitants of the abyss.