Japanese researchers have discovered the ability of the amphipods Hirondellea gigas, living at the bottom of the Mariana Trench, to create a personal "armor" based on aluminum. This extra shell helps the tiny crustaceans withstand the immense pressure and coldness of the deep sea. They never float above 4.5 km from the surface of the water and have developed a unique defense mechanism for survival in extreme conditions.
The main food of Hirondellea gigas is sea plants, for the digestion of which their digestive system releases chemical solvents. In addition to food, these crustaceans also absorb metal-rich bottom sediment, so aluminum ions become a by-product of their vital activity. Once in an alkaline environment in the depths of the ocean, they turn into aluminum hydroxide, which covers the body of the animal in the form of a shell.
This gel armor serves as thermal protection and can contract to compensate for high pressures. Also, aluminum hydroxide traps calcium carbonate, which is very important for the strength of the exoskeleton of Hirondellea gigas. There is also a version that such a substance is "tasteless" for predators, and therefore helps to protect the crustacean from them. The result is a versatile armor that, while in need of constant renewal, fulfills many vital functions for Hirondellea gigas.
It is possible that this discovery will create the technology of new protective systems for working at great depths, which will replace clumsy spacesuits and bathyscaphes. The extremely hostile conditions of the ocean trenches, it turns out, are not at all an obstacle to life.