“Xiangshou Crab” has become a hot topic. Are pet crabs going to become internet celebrities?

Recently, crabs have suddenly become popular as pets - multiple online shopping platforms have launched pet crabs and given them names such as "Xiangshou Crabs".

Raising crabs as pets is not a new thing, but it has only become popular in recent years . As far as I can remember, about 20 years ago, small crabs called "watermelon crabs" or "couple crabs" were sold as pets in the aquarium market. At that time, I even believed the merchants and fed these crabs with watermelons - needless to say, they all died within half a month.

Later, more and more types of crabs were available in the aquarium market, with various names, such as devil crab, general crab, red claw crab, etc. However, there are still only a few people who like crabs and keep them as pets, and crabs are still a niche and unpopular pet.

Until recently, "Xiangsuo Crab" suddenly became a hot search. Are pet crabs finally going to become Internet celebrities? I think this may not be a good thing for the crabs themselves.

What kind of crab is it?

Let’s first sort out what are the types of crabs with the highest exposure in the aquarium market.

First up is the internet-famous "Xiang Shou Crab", whose name is actually the Seshou Crab . In the aquarium market, the most common Seshou Crabs include two species. One is the dark red Chinese Oriental Seshou Crab , which is what is sold on the online platform this time. It is also often called the "Red Claw Seshou Crab" by merchants (the name "Red Claw Seshou Crab" is also inaccurate, the real "Red Claw Seshou Crab" is the Red Claw Mantis Seshou Crab).

Chinese Oriental crab (Orisarma sinense)｜Photographed by Zhang Xiaofeng

Another common species of crab is the toothless Oriental crab . They are dull in color but are given the slightly domineering name of "General Crab".

Toothless Oriental Sesarma (Orisarma dehaani)｜Photographed by Zhang Xiaofeng

These two types of crabs like to live in estuaries where fresh and salt water meet, and they dig holes in the mud on the shores with dense vegetation. They are both widely distributed. The Chinese Oriental Sesarma is distributed from the Yangtze River estuary in Shanghai to Guangdong. This type of crab has also been recorded in the northern part of Hainan Island, but I have not found it in my field surveys so far. The toothless Oriental Sesarma can be found as far north as southern Zhejiang to northern Fujian. Further north to the Yangtze River estuary is its closely related species, the cryptic Oriental Sesarma. The two are similar in appearance, and some taxonomists even believe that they should be classified as the same species.

Although the movement distance of adult Sesarma crabs is limited, their planktonic larvae can reach inland lakes and rivers with the help of water currents. Therefore, Sesarma crabs can also be found in many rivers and lakes that are deep inland and are completely unaffected by tides.

Another type of crab that is often seen as a pet is the "watermelon crab". When I was a kid, I thought it really ate watermelon, but later I thought maybe it just looked like watermelon. The Chinese name of this crab is Licai Niuxianchao , and it can be found in estuaries and inner bays south of Fujian, especially around mangroves.

Uca splendida｜Photo: Zhang Xiaofeng

The "watermelon crabs" that can be bought in the market are almost all male without exception. Don't listen to the claims of some merchants that "the left claw is larger for males and the right claw is larger for females". No matter how you match them, you are forcing them to be "gay". The exaggerated large claws on one side of male fiddler crabs are their weapons for courtship and driving away intruders, but female fiddler crabs do not have such needs, so both claws are small. Because of this, female crabs are not popular, and only male crabs are "marketable".

These two types of crabs have been sold as pets for some time, but sand crabs are a recent phenomenon. Most of the crabs sold by merchants are Chinese sand crabs , which are distributed in China from Zhejiang to the south. They like to dig holes in places with vegetation such as coastal forests that are a certain distance from the sea. Chinese sand crabs have a strong tolerance to salinity and can be found wherever there is sand, whether it is on the coast where salinity is relatively stable or around estuaries where salinity varies.

Chinese sand crab (Ocypode sinensis) | Photographed by Zhang Xiaofeng

In addition to the above crabs that have become popular recently due to online supermarket platforms, crabs that can be seen in the aquarium market include "chili crabs" (Taiwan mud crabs), "devil crabs" (genus Chironomids, mostly introduced from abroad) and some freshwater crabs (such as South China Sea stream crabs, etc.), as well as huge and long-lived land crabs, such as Lamarck's imitation land crabs, fierce round-axis crabs, and even "rainbow crabs" (armed round-axis crabs) and giant three-legged crabs introduced from abroad.

Is it illegal to raise crabs?

Now comes the most important question: Can these crabs be raised? Is it legal?

What is certain is that none of these common crabs on the market have been listed as protected animals . Therefore, as long as they are not caught in protected areas and not illegally imported from abroad, it will not be illegal for businesses to sell these crabs to the public for purchase and breeding.

In ecology, crabs are typical r-strategists, and they maintain their populations by producing a large number of offspring. Many crabs, including "Xiangshou crabs", "Watermelon crabs" and "Chili crabs", have large populations in the wild, and human capture does not seem to have any impact on their populations - in contrast, habitat protection is more important to them .

Protecting habitats is important | Leon Petrosyan / Wikimedia Commons

However, all of the above are just inferences based on the habits of crabs, lacking specific data. There has been no scientific assessment of the population of a certain type of crab in a certain area in China, so there is currently no scientific data to support whether artificial capture will have an impact on their population .

Before these pet crabs became "Internet celebrities", the limited demand for their capture did not have a significant impact on the population. But after they became "Internet celebrities", the number of their captures will inevitably increase in order to meet the greater market demand . There is currently no data to support whether this sudden increase in capture pressure in the short term will have an impact on the population in the capture area, and how long it will take for the population to return to its original level.

On Xiaohongshu, the topic "Xiangshou Crab" has been viewed 6.65 million times.

I don't object to people buying and raising these pet crabs. After all, raising pets is a spiritual need of human beings. But it must be pointed out that if you want to raise them, please first fully understand the biological learning ability of crabs before deciding whether to buy them. Don't blindly follow the trend .

What to raise? How to raise?

Not all crabs are suitable for breeding in artificial environments , such as "chili crabs" and "watermelon crabs" that are often kept as pets.

"Chili crabs" and "Watermelon crabs" have unique habitats and feed on tiny organic matter in the mud and sand. They are quite dependent on the tidal pattern. Their caves will be completely submerged by water due to tidal changes, but they will choose to come out after the tide goes out, so they do not like to be completely submerged in water for a long time. Such a living environment in the wild is difficult for ordinary breeders to completely imitate, and it is difficult to keep them in an artificial environment for a long time .

Therefore, I do not recommend that you raise these crabs - apart from being beautiful and fun to watch, the so-called raising of them is entirely about consuming their lives to please the breeder .

Taiwanese mud crabs (Ilyoplax formosensis), which are called "chili crabs" by merchants, cannot survive in artificial breeding for a long time. Photographed by Zhang Xiaofeng

Sesarman crabs and sand crabs can usually be raised in fresh water or seawater with a certain salinity , but this does not mean that you can raise them well by raising them casually. Since you have purchased them, you should raise them according to their habits and be responsible for their lives.

Sesarma are omnivorous crabs that eat fruits and vegetables, as well as small fish and shrimp. Adult Chinese Oriental Sesarma and Toothless Oriental Sesarma can adapt to a pure freshwater environment. Although they will dig holes in the soil in the wild, in order to keep the environment clean in captivity, they are generally covered with a layer of pebbles and given clean water about 1 cm above the bottom sand. Of course, it is also necessary to provide them with appropriate objects for climbing or hiding. Sesarma crabs in the wild usually live in clusters, but each of them usually has its own independent cave; if there is insufficient hiding space in artificial breeding, they are likely to cannibalize each other when food is scarce , especially crabs in the molting period, which are easily preyed upon by other individuals in the same breeding box, so special attention needs to be paid to providing enough hiding space.

Sand crabs and Sesarma crabs are kept in similar environments, but they prefer meat. In addition to providing clean fresh water, seawater is also needed for them to choose to use.

Parasesarma continentale in the natural environment. The muddy environment makes it easy for them to dig holes and hide.｜wetlandpark.gov.hk

Pet crabs have always been a niche product, and we are still not sure whether the popularity of pet crabs on some platforms will cause a fatal blow to their population. But one thing is certain: the merchants who hype pet crabs as "cat toys" have no bottom line.

People who choose to buy pets should not just follow the trend, after all, they are buying a life. Keeping a pet requires time, money and energy, and it is not an interest without barriers . Especially for animals like crabs, it is not as simple as buying a small plastic box and filling it with water to keep them alive.

Most importantly, except for a few species such as "devil crabs" or stream crabs, most pet crabs have to return to the sea to reproduce; at least their larvae must be in water with a certain salinity, and after a few weeks or even a month of floating life, they will eventually become real juvenile crabs through metamorphosis. In other words, these crabs are all caught from the wild, and no matter how long they are raised after being caught, they can no longer make any contribution to the wild population .

Therefore, even if it is not illegal to buy these crabs, I still do not recommend that you buy them blindly for the sake of protecting biodiversity. If you are really interested in crabs, then observe them instead of catching and raising them.

Author: Zhang Xiaofeng

Editor: Mai Mai