In order to record the most ordinary rare animals, I wrote a book for clams

River clams, a type of creature that is familiar yet unfamiliar to us - most people call them clams or "gala" and know them by frying, stir-frying, and deep-frying.

China is one of the countries with the richest clam species in the world. Clams can be found in rivers, ponds and paddy fields. However, most people don’t know that the seemingly common clam is one of the most endangered animal groups on the planet.

Since I was a child, I have been very curious about the species of clams in the riverside of my hometown. This question was buried in my heart, and decades later I was finally able to compile an atlas of Chinese freshwater bivalves and solve this mystery myself.

Sinohyriopsis cumingii, a mullet, is often used in pearl farming. This photo was taken by the author during a dry winter in Jiangxi | Guo Liang

The most common rare species

My first contact with river clams originated from a close friend, Mr. Ye Mao, who lived near the Yangtze River. We were both natural history enthusiasts and often communicated with each other. One time, he brought me two thick clam shells as a gift. The thick shells were hard and had a silky luster, and the surface was covered with tumor-like protrusions. Such strange clam shells were beyond my understanding of river clams, and thus I started my unfinished journey to find river clams.

How did Mr. Ye Mao come to know about river clams? When he was a primary school student, he collected river clams on the banks of the Han River in Hubei. At that time, he did not realize that the Yangtze River is a hotspot for river clams diversity in China, so the riverbanks are full of clams of strange shapes. Today, decades later, it seems that even the remains of clam shells are hard to find on the banks of the Han River.

Over the years, Mr. Ye Mao has been collecting river clam specimens and has accumulated a lot of valuable information for me to make a river clam illustration. Fortunately, river clams are not like fish, birds and insects. Even if they become extinct, they will leave hard shells buried in the riverbed, which can be preserved for thousands to tens of thousands of years.

A variety of clams on the shore of Poyang Lake | Guo Liang

If you want to sort out and classify river clams, you must first obtain specimens for comparison. For me, finding river clams is not an easy task: I am an insect lover, and the forests in the mountains and hills are the environment I am most familiar with; most river clams live in rivers with a certain flow rate and natural lakes, buried in the mud and pebbles of the riverbed, and many species live underwater at a certain depth. I can't swim, which makes things even worse.

In my spare time, I started looking up materials and preparing a plan. I searched for collection tools on a shopping app and recalled the clam rakes I used to collect snails by the river when I was a child. This is an excellent investigation tool. However, the riverbed environment is very complex. Some parts are made of mud and sand, and some are made of rocks. Rocks can get stuck on clam rakes. In places where clam rakes cannot be used, I wait for the dry season of rivers and lakes, and then go down to search and explore after the water level recedes.

The giant head pseudo-wedge clam Pseudocuneopsis capitatus was originally widely distributed in the middle and lower reaches of the Yangtze River. Now the population has been extremely reduced to only be seen in certain tributaries | Guo Liang

Poyang Lake has become a cemetery for river clams

After reading a lot of literature, I locked on Jiangxi and Hunan, two provinces with large river clams, as the collection sites. Poyang Lake in Jiangxi is the largest freshwater lake in China, with a dense network of waterways, and is the home of river clams. So I made a plan to go and take a look.

2019 is an El Nino year. The daytime temperature in Jiangxi at the end of November was still around 25℃, the second highest in history. Our group came to the Poyang Lake in Jiangxi, which has experienced the worst drought in history. The dry season in 2019 came early and left late. Poyang Lake entered a dry season in July, which was a disaster for river clams.

Poyang Lake is covered with shells of the cave clams Lamprotula caveata | Guo Liang

Hundreds of millions of clam shells lie on the dry riverbed.

Although some clams can use their axe feet to dig and hide in the mud of the riverbed to lie dormant, not all clams can do this. Those burrowing clams are directly "sent away". For example, the olive clams and the dragon bone clams, they burrow in the riverbed, and their two shells cannot close well, so they will quickly dehydrate when the dry season comes. The same is true for species of the genus Lysimachia, which have hard and thick shells, which can protect them from predators, but also make escape more difficult. Most clams will sink deep into the mud, but even if they dive into the mud, they will be suffocated to death under the scorching sun.

Sinosolenaia oleivora, the olive razor clam, has a highly adapted morphology to cave dwellings and is unable to escape due to low water levels | Guo Liang

The dead mussels became food for birds. Bird watchers were delighted, but we could only smell the smell of death. What made us most desperate was that we couldn't even find the shells of some rare species. They might have disappeared long ago. Whether it was day or night, we were either looking for mussels or on the way to find them. In the short sleep time, we even dreamed about them, but some species still did not show up.

Leaving a record for the lost clams

There are countless rivers and lakes in China, and the story of the search goes far beyond this. Later, more people joined us, from a PhD studying moths to beetle experts, fish scholars and snail doctors, as well as fishermen and workers who lost their jobs due to the epidemic, as well as primary school students and college students - regardless of occupation, age or region, everyone is helping me. Later I found that Poyang Lake is the best place to find river clams. Dongting Lake in Hunan, the Pearl River in Guangdong, the Lancang River and Yingjiang in Yunnan, and the Heilongjiang River are not as easy as Poyang Lake, the "cemetery of river clams". In some places, even the empty shells of river clams cannot be seen.

After searching for many river mussel specimens, I began to draw them, using the most primitive line drawing method, so as to highlight their morphological characteristics and facilitate identification. Because I am an insect lover, I know that the best way to understand morphology is to draw them.

Line drawing of a river clam by the author | Guo Liang

With human development activities, a large number of species are on the verge of extinction, and the river mussel group is also facing a major blow. Since the 20th century, the global freshwater bivalve population has declined significantly. According to the IUCN Red List of Endangered Species, 200 river mussel species are on the verge of extinction. Bogan (1998) pointed out that 297 river mussel species were recorded in North America, 19 of which were extinct by 1993, and the number of extinctions reached 35 by 1998.

Rare ecological photos of the multi-tuberculate sharp-pointed clam Aculamprotula polysticta. No one has ever taken ecological photos of this species before. Both its living and dead shells are very rare. | Guo Liang

Most river clams have complex life histories, are fragile, and have long development cycles, making them one of the most difficult animal groups to recover and protect. As of 2008, 37 species of river clams were known to be extinct, and 168 were close to extinction or critically endangered - and the real number is much higher than this. The more I learn about river clams, the more helpless I feel. If I don't race against time to record them, the existence of these river clams may become a legend in the future.

As time went by, the book was finally published. When we went to the publishing house to read the manuscript, I and the editorial team were so excited that we couldn't sleep. It might be because we had invested countless efforts and hard work, or it might be because the results of our efforts were finally presented. A few days before the proofing started, I had a dream: I don't know how many years later, when our descendants open this book, they will be surprised to say that there are so many strange shells in our rivers!

"River Clams" is not a recipe book, but an apocalypse of China's rivers.

Author: Guo Liang

Editor: pee pee shrimp

This article comes from the Species Calendar, welcome to forward

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