Giant tridakna - the largest mollusc

Surely many of you have heard that the verya large bivalve was caught in 1956 near the coast of the Ishigaki island of Japan. They were a giant tridakna, weighing 333 kilograms at a length of 1.16 meters. After reading today's article, you will learn more about this inhabitant of underwater depths.

Habitat

These giants inhabit the depths of the Indian and Pacificoceans. But the real kingdom of tridakn is the Great Barrier Reef, located off the coast of Eastern Australia. It is here, in the vast shallow spaces, densely overgrown with all kinds of corals, is inhabited by the largest mollusk.

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.

Features of the structure

Giant tridacna has a huge shell,consisting of two upwardly directed flaps. The mantle of the mollusk is nothing more than a fold of the skin. It consists of two layers. Outer - glandular, and on the inside are special cilia, thanks to the movements of which the mantle cavity gets water.

In addition, the largest mollusc in the world hasgills, outwardly resembling modified ktenidii. Each of them consists of two plate-like parts. These halves are connected to each other by means of so-called filiform petals. Gills tridakny perform the function of a filter that detaches particles of food. Also, this huge inhabitant of the sea depths have V-shaped buds, one end of which opens into the pericardium, and the second - into the mantle cavity.

Brief description of appearance

Just note that this giant shellfishstriking in its size. Its length can reach one and a half meters, and the mass is about two hundred kilograms. In addition, there are officially recorded cases of the capture of more impressive specimens. As mentioned earlier, the tridakna, caught off the Japanese coast, got into the Book of Records.

Interestingly, the average life expectancyThese huge creatures are about three centuries old. The largest mollusc is striking in its variety of colors. In nature there are gray, yellow, blue, blue, turquoise, green and brown individuals. It is proved that the shade is determined by the color of unicellular algae living in the mantle of giants. As for the shell, its colors are not so diverse. As a rule, it is covered with soil particles.

Reproduction

Just note that the largest mollusk -hermaphrodite. But they are unique in that they have the ability to cross-fertilize. The larger the population of tridacts, the higher the chances of their future offspring. It is known that one sexually mature individual is able to throw several million eggs.

As a result of fertilization, they appearthe smallest eggs, and a little later they turn into larvae with soft shells, which are called trochophores. For the next fourteen days, they move with plankton in ocean waters. Growing up, they settle to the bottom and begin to actively search for the ideal place for a future home. Having found a suitable substrate, young tridacs cling to it with the help of bisus threads. As they develop, these mounts gradually die off. The matured individuals lie calmly on the bottom, keeping there with their own weight.

What does the largest clam eat?

The basis of his diet is plankton and a suspension,consisting of organic particles in the water column. The food is provided by filtering the liquid entering the mantle cavity of the tridacna. Food mixed with water moves at the expense of cilia. As a result, small pieces of food, previously separated from mineral impurities, enter the mouth of the mollusk, which is located near the anterior muscle of the closure. From there they enter the esophagus, and then into the stomach. From the latter, the anterior intestine, gradually transforming into the posterior one, emerges.

In addition, these gigantic marine lifeThe depths are fed by symbiotic algae or zooxanthellae. They hide in the thick folds of the mantle cavity of the mollusc and periodically digested by them.

Application

Since ancient times, the shells of this beautiful giantwere used by the local population as a building material. In addition, they made all kinds of crafts and household items. Also, from the wings were cut circles that perform the functions of coins.

Occasionally for tridaknami they hunt for the sake of pearls. According to some reports, a specimen weighing about seven kilograms and a length of twenty-three centimeters was found in one of the shellfish. In recent years, the shells of these creatures are actively bought up by tourists. Therefore, the population of tridacne began to decline.