Surely many of you have heard that the largest bivalve clam was caught in 1956 off the coast of the Japanese island of Ishigaki. It turned out to be a giant tridakna, 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 Great Barrier Reef, located off the coast of East Australia, is considered the real kingdom of tridacs. It is here, on the immense shallow spaces, densely overgrown with all kinds of corals, the largest mollusk lives.
In addition, it can be seen in the waters of the Red Sea. Interestingly, they inhabit not only shallow water, but also depths not exceeding one hundred meters.
Structural features
The giant tridacna has a huge shell, consisting of two upward-facing flaps. The clam mantle is nothing but folds of skin. It consists of two layers. The outer is glandular, and on the inside there are special cilia, thanks 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 through 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.
Brief Description of Appearance
Just note that this giant clam is striking in its size. Its length can reach one and a half meters, and the mass is about two hundred kilograms. In addition, officially registered cases of the capture of more impressive specimens are known. As mentioned earlier, the tridacna caught off the Japanese coast ended up in the Book of Records.
Interestingly, the average lifespan of these huge creatures is about three centuries. The largest mollusk affects a variety of colors. Gray, yellow, blue, blue, turquoise, green and brown individuals are found in nature. It is proved that the hue 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.
Breeding
Just note that the largest clam is hermaphrodite. But they are unique in that they have the ability to cross-fertilize. The larger the number of tridac population, the higher the chances of their future offspring appearing. It is known that one sexually mature individual is capable of throwing several million eggs.
As a result of fertilization, tiny 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, together with plankton, move in oceanic waters. Growing up, they settle to the bottom and begin to engage in active searches for the ideal place for future housing. Having found a suitable substrate, young tridacs cling to it with the help of byssus threads. As they develop, these mounts gradually die off. The matured individuals calmly lie at the bottom, holding there with their own weight.
What eats the largest clam?
The basis of his diet is plankton and a suspension consisting of organic particles located in the water column. Food is provided by filtering the fluid entering the mantle cavity. Food mixed with water moves through cilia. As a result, small pieces of food, previously separated from mineral impurities, enter the mollusk's mouth, which is located near the anterior muscle-closure. From there, they enter the esophagus, and then into the stomach. The anterior intestine departs from the latter, smoothly transforming into the posterior.
In addition, these giant inhabitants of the deep sea feed on symbiotic algae or zooxanthellae. They hide in the thick folds of the mantle of the mollusk and are periodically digested by it.
