Surely many of you have heard that the largest bivalve mollusk was caught in 1956 off the coast of the Japanese island of Ishigaki. It turned out to be a giant tridacna, weighing 333 kilograms with a length of 1.16 meters. After reading today's article, you will learn more about this inhabitant of the underwater depths.
Habitat
These giants inhabit the depths of the Indian and Pacific Oceans. But the real kingdom of the tridacna is considered to be the Great Barrier Reef, located off the coast of Eastern Australia. It is here, in the vast shallow waters, densely overgrown with all kinds of corals, that the largest mollusk lives.
In addition, it can be seen in the waters of the Red Sea. It is interesting that they inhabit not only shallow water, but also depths not exceeding one hundred meters.
Building features
Giant tridacna has a huge shell, consisting of two flaps directed upwards. The mantle of a clam is nothing more than folds of skin. It consists of two layers. Outer - glandular, and oninside there are special cilia, due to the movements of which water enters the mantle cavity.
In addition, the largest mollusk in the world has gills that look like modified ctenidia. Each of them consists of two plate parts. These halves are connected to each other by means of the so-called thread-like petals. The gills of the tridacna act as a filter that filters out food particles. Also, this huge inhabitant of the deep sea has V-shaped kidneys, one end of which opens into the pericardium, and the other into the mantle cavity.
Short description of appearance
We note right away that this giant clam is striking in its size. Its length can reach one and a half meters, and its mass is about two hundred kilograms. In addition, officially registered cases of the capture of more impressive specimens are known. As mentioned earlier, a tridacna caught off the coast of Japan made it into the Book of Records.
Interestingly, the average lifespan of these huge creatures is about three centuries. The largest mollusk impresses with a variety of colors. In nature, there are gray, yellow, blue, blue, turquoise, green and brown individuals. It has been proven that the shade is determined by the color of unicellular algae living in the mantle of giants. As for the sink, its colors are not so diverse. As a rule, it is covered with particles of soil.
Reproduction
We note right away that the mosta large mollusk is a hermaphrodite. But they are unique in that they have the ability to cross-fertilize. The larger the population of tridacnids, the higher the chances of their future offspring. It is known that one sexually mature individual is capable of throwing several million eggs.
As a result of fertilization, the smallest eggs appear from them, and a little later they turn into larvae with soft shells, which are called trochophores. Over the next fourteen days, they move along with plankton in ocean waters. Growing up, they settle to the bottom and begin to actively search for the ideal place for their future home. Having found a suitable substrate, young tridacnids cling to it with the help of byssal threads. As they develop, these attachments gradually die off. Mature individuals lie quietly on the bottom, holding there with their own weight.
What does the largest clam eat?
The basis of its diet is plankton and suspension, consisting of organic particles found in the water column. Nutrition is carried out by filtering the liquid entering the mantle cavity of the tridacna. Food mixed with water is moved by cilia. As a result, small pieces of food, previously separated from mineral impurities, enter the mouth of the mollusk, which is located near the front muscle-contactor. From there they pass into the esophagus and then into the stomach. The anterior intestine departs from the latter, smoothly transforming into the hindgut.
In addition, these giant sea creaturesdepths feed on symbiotic algae or zooxanthellae. They hide in the thick folds of the mollusk's mantle cavity and are periodically digested by it.
Application
Since ancient times, the shells of this beautiful giant have been used by the local population as a building material. In addition, all kinds of crafts and household items were made from them. Also, circles were cut out of the wings, performing the functions of coins.
Sometimes tridacnae are hunted for pearls. According to some reports, a specimen weighing about seven kilograms and twenty-three centimeters long was found in one of the mollusks. In recent years, the shells of these creatures have been actively bought by tourists. Therefore, the tridacnid population began to decline.
