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Why can Hirondellea gigas survive in the deepest bottom in the world? –Part II

Updated: Jul 1, 2022

Hirondellea gigas
Hirondellea gigas, the creature in the deepest sea

Due to the high water pressure in the deep sea, it is difficult for many organisms to survive. Especially in the deep sea where the water depth exceeds about 5000 m, carbonates begin to dissolve. That depth is called the carbonate compensation depth (abr. CCD). The deeper the depth, the faster the carbonate will dissolve. Seashells, bones, shrimp shells, etc. are made of calcium carbonate. Therefore, organisms cannot maintain their shape without special elution prevention method. Fish bones are contained in their bodies. Dissolved calcium can be used to rebuild bones in the body. When calcium dissolves from the shell, it diffuses into seawater and cannot be recovered. Shellfish promote the crystal synthesis of calcium carbonate and maintain the strength of the shellfish. Some species of deep-sea mussels were found deeper than CCD. The shrimp also can synthesize crystal calcium carbonate. Different from clam or mussel, shrimp cannot grow without molting. Molting remove all crystal calcium carbonate from body. After molting, it is difficult for shrimp to reconstruct shells containing crystalline calcium carbonate in the deep sea. Hirondellea gigas, a member of the shrimp, also molts. How can Hirondellea gigas sustain its shells in its life cycle?

Hirondellea gigas wears aluminum hydroxide gel to protect its shell.

When researchers observed surface of Hirondellea gigas, aluminum element covered its body. Aluminum forms an aluminum hydroxide gel in a weakly alkaline environment such as seawater. Aluminum hydroxide gel protects shell and keeps dissolved calcium around shell. As a result, Hirondellea gigas can maintain its shell in during its life cycle in the deepest part in the world. Hirondellea gigas is the first animal on the planet to use aluminum for environmental adaptation.

How does Hirondellea gigas get aluminum?

Aluminum is almost insoluble in seawater. The aluminum content in seawater is approximately 1 micro-g / L. It is lower than the uranium content in seawater. On the other hand, Aluminum is abundant in seafloor sediments. Hirondellea gigas eats sediment to eat plant debris. This can be a chance to get aluminum. However, can Hirondellea gigas get aluminum from sediment? Researchers experimented with the extract to see if it could extract aluminum from the sediment. As a result, aluminum was released from the sand in sediment. Hirondellea gigas has extractor of aluminum from sand. And scientists have revealed the substances that extract aluminum. It was gluconolactone. Gluconolactone is made from glucose by an enzymatic reaction. Glucose is also poor in the deep-sea, because there is no plants in the deep-sea. However, Hirondellea gigas can easily obtain glucose from plant debris by its unique cellulase. Unique cellulase allows Hirondellea gigas to survive in the deepest point in the world. If you want to know about Hirondellea gigas, please check my paper.

We sell a resin embedded specimen of Hirondellea gigas.

Hirondellea gigas lives in the deep trenches including Challenger Deep of the Mariana Trench. And it is one of the well-studied deep-sea creatures. Its feature is very unique and interesting. We have succeeded in producing the resin embedded specimen of Hirondellea gigas. This specimen retains its shape and color when it was alive. We believe this specimen. We believe this specimen is suitable for museum exhibition. If you interested in resin embedded specimen of Hirondellea gigas, please ask us via E-mail.

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