The largest pearl in the world is as heavy as a husky

The name of Tridacna is quite obscure, and is generally known only to those who specialize in research and those who live by the sea. As a typical inland person, I only learned about this difficult-to-pronounce name a few years ago, but it was long before I met it.

It's time to reveal my age: In the 1986 version of Journey to the West, Wukong and Bajie jumped into the Bi Bo Lake to find the son-in-law of the Wansheng Dragon King, the Nine-headed Insect. During the fight, Bajie's foot was caught by a huge shell, which was actually a giant clam! Does it make sense?

Giant clam's giant shell | Neutcomp / Wikimedia Commons

In addition to this scene, in the episode of Dragon Palace Treasure Hunt, every scene with the Crystal Palace has a large white shell with vertical stripes all over it, which is a giant clam carefully prepared by the props team. Giant clams are actually marine animals, and it is reasonable for them to appear in the Dragon Palace in the East China Sea, but it is not rigorous to appear in the Bibotan.

The "Man-Eating" Shell

So now recalling, the only impression that giant clams give me is: big. And this is also the most obvious feature of giant clams. Giant clams are the largest bivalve molluscs in the ocean, belonging to the class Bivalvia, the order Tridacna, the family Tridacna, and the genus Tridacna.

The largest known giant clam has a shell length of 1.4 meters and a maximum individual weight of 263 kilograms. If this giant really clamps a person's foot, the possibility of escape is extremely small, so the giant clam is called the man-eating clam. There is such a record in the Philippines, where a fisherman with excellent swimming skills dived to pick up seafood, but his companions did not see him surface for a long time, so they went into the water to look for him and found that he was clamped tightly by a large giant clam and eventually suffocated.

Giant clam | Rick Hankinson / Wikimedia Common

In the children's adventure novel "The Adventures of Hal Roger" (another opportunity to reveal my age), a scientist was caught by a giant clam and asked the villain to cut off his leg. Even the cruel villain couldn't do it, so he had to stay there and drown. It was really a childhood shadow. Thank God, giant clams close very slowly, and some old giant clams have uneven shells that cannot be closed tightly, so such accidents rarely happen. Giant clams are not only the orange cat giants among shellfish, but also have a considerable lifespan. According to records, their lifespan can be as long as 80-100 years.

The mantle of a giant clam is brightly coloured | Mal B / Flickr

Oversized (and ugly) pearls

In addition to its length and weight, giant clams are large in many aspects. Let's go back to Journey to the West. You must be familiar with this scene: the dragon girl chanted a spell, and a huge giant clam slowly opened its shells, revealing a glittering pearl... Many people have questions: can there be pearls in giant clams?

Yes, there are. Not only that, giant clams are huge, so the size of pearls is also not ambiguous. The largest pearl in the world is undoubtedly the giant clam pearl. It is called the Pearl of Puerto. It is about 67 cm long and weighs 34 kg. This size should not be called a pearl. It is comparable to a large winter melon. The Pearl of Puerto was discovered by fishermen on Bawang Island in the Philippines more than ten years ago, and it was not exhibited to the public until 2016.

A replica of the Pearl of Allah, with its uneven surface | Fernando Losada Rodríguez / Wikimedia Commons

The most famous giant clam pearl was discovered in 1939. It is called Allah's Pearl and is also quite huge, weighing 6.4 kilograms. Imagine opening a giant clam and finding a "big winter melon" inside. Ordinary pearls don't smell good at all. But big does not necessarily mean high appearance. The huge giant clam pearl is not as round as we imagine, but rugged and oddly shaped. The surface of the Allah Pearl is full of grooves, like the wrinkles on the face of an old man. Some people think it resembles an elder in the Spring and Autumn Period - Laozi, so this pearl is also called Laozi Pearl. Moreover, there is no nacre on the surface of the giant clam pearl, so it does not have the effect of "beautiful pearls".

Another feature of giant clams is that their skin is not thin and their fillings are large. The thickness of a snail shell is estimated to be only 0.1 mm, and we can easily crush it. But the shell of a giant clam can be more than 10 cm thick, and more than 86% of its components are very hard calcium carbonate. The thick and hard double shell has attracted the attention of the cultural and art circles. Various giant clam shell crafts are illegally traded online and offline, and the giant clam population in my country's South China Sea has been severely reduced.

Giant clam water bowl | Frank Vincentz / Wikimedia Commons

In 2018, my country's Ministry of Agriculture and Rural Affairs issued a document stipulating that, except for the giant clam (Tridacna gigas), which maintains the first-class protected animal rating, other giant clams are treated as second-class protected animals. And this year's newly adjusted "National Key Protected Wildlife List" even listed the wild populations of five giant clams as second-class protected. So if you buy a giant clam bracelet, you will be in jail for life. Moreover, Buddhism advocates compassion. If you wear the remains of rare animals on your body, can you still say that you are sincere to Buddhism?