Using golden apple snails to impersonate field snails and sell them? One golden apple snail contains 6,000 parasites!

Crowd terror warning! Crowd terror warning!

Some time ago, The Paper investigated the industry chain of the Golden Apple Snail and found that after being shelled and processed, the snails were "disguised" as field snail meat and then flowed into the market.

The price of golden apple snails caught from the wild is extremely low, several times the price of field snails. After the golden apple snails are peeled and skewered or cooked, it is difficult to distinguish whether they are field snails or golden apple snails. The person in charge of a golden apple snail processing factory said that the sales volume of golden apple snails is several hundred tons a year , mainly sold to restaurants and pre-prepared food processing factories.

A snail vendor displays frozen golden apple snail meat near Heping Bridge in Hanshou County, Hunan Province｜Xia Ruchu

It is disgusting to think that the delicious snail meat you eat outside may actually be golden apple snails. You know, golden apple snails were famous for a terrible zoonosis parasite, Angiostrongylus cantonensis .

The eggs of the golden apple snail are pink but scary｜Judgefloro / Wikipedia

An accident caused by golden apple snails

Back to 2006, 18 years ago, from the end of May to the end of August of that year, more than 100 cases of Angiostrongylus cantonensis were confirmed in Beijing. This is a parasitic disease caused by Angiostrongylus cantonensis, a foodborne parasitic disease. Patients experience symptoms such as headache, fever, and stiff neck.

In theory, humans are not normal hosts of Angiostrongylus cantonensis . Their intermediate hosts should be terrestrial snails, slugs, etc., and the final host is rodents. Infection with Angiostrongylus cantonensis must be caused by eating infected organisms.

Angiostrongylus cantonensis｜Punlop Anusonpornperm / Wikipedia

After investigation, it was found that most of the more than 100 patients had eaten the cold-mixed snail meat from a restaurant in Beijing. This cold dish made with golden apple snails does not cook the snail meat thoroughly, because this can ensure the taste of the snail meat. Later, in the test of the golden apple snails, the presence of Guangzhou roundworms was confirmed. For a time, food and drug administrations across the country issued documents prohibiting the sale of golden apple snails. The reputation of golden apple snails suffered a cliff-like decline.

Snail meat may look delicious, but it may actually be dangerous｜Eric Danell & Emily Driskill / wordpress

This is not the first time that the golden apple snail has encountered a crisis of trust among people. As early as the 1990s or even earlier, the golden apple snail left a bad impression on people at that time because it harmed agricultural production. The golden apple snail is now a notorious invasive species, but when it was first introduced, people had many good expectations for it.

High-yield snails from South America

The golden apple snail is a large freshwater snail native to the Amazon Plain and the La Plata Plain in South America. The climate here is warm, with an average annual temperature between 14 and 25 degrees Celsius. They are omnivorous animals with a wide range of diets, mainly feeding on plants, organic debris and animal carcasses, but they prefer to eat a variety of aquatic plants. When the opportunity comes or there is no choice, they will also try their luck on land. The ability to go between waterways is due to the " amphibious equipment " they are equipped with: in the water, they can use gills to absorb oxygen from the water; after leaving the water, they can use water tubes to absorb air and breathe through lung sacs.

Illustration of the golden apple snail | British Museum / Wikipedia

The growth and reproduction of golden apple snails are very dependent on temperature . When the temperature is too low, the golden apple snails will stop growing and reproducing. Under normal circumstances, it only takes 50 days for them to reach sexual maturity . Golden apple snails are dioecious and fertilization is done internally. In warm tropical areas, golden apple snails can reproduce throughout the year, while in temperate areas, reproduction only occurs in the warm early spring to early autumn.

About a week after mating, the female snail will lay eggs. They are very particular about the timing and location of spawning. Generally, female snails will choose the evening when the sun sets, which is a good time to lay eggs. The female snail with a belly full of eggs will crawl out of the water along the stems of aquatic plants, look at the height of the stems from the water surface, and choose a location more than 10 cm above the water surface to lay eggs. The eggs they lay are about 2 mm in diameter and are adhered to each other by mucus. These egg masses will form a grape-shaped red egg mass after natural air drying, and such an egg mass contains 200 to 500 eggs.

Egg laying in progress｜Alchetron

The fertilized eggs of the golden apple snail will hatch in about two weeks, and the hatched young snails will fall into the water and continue to grow . If nothing goes wrong, these newly hatched young snails will only need at least 50 days to join the breeding army. The high egg carrying capacity and the short sexual maturity time of the offspring give the golden apple snail an amazing reproductive ability. It is estimated that a pair of golden apple snails can produce tens of thousands of offspring in a year .

The Darkening Path of the Golden Apple Snail

The huge size of the golden apple snails, their considerable meat content and their amazing reproduction rate have made people see their potential for breeding .

In 1980, a box of golden apple snail eggs from South America was brought to Taiwan, China, by an Argentine overseas Chinese for hatching. At the end of that year, golden apple snails were promoted for breeding in Taiwan under the name of "Golden Treasure Snail". The following year, golden apple snails were introduced to mainland China. Subsequently, they were bred in many countries including the Philippines, Vietnam, Japan and Thailand. At that time, breeding this kind of big snail seemed to be a sure-win business. For a time, a breeding boom of golden apple snails was set off in various countries.

Albino golden apple snails are sometimes used for ornamental purposes｜Michael Radtke / flickr

As time went by, people found that the meat of golden apple snails was not good and could not win the favor of diners . Farmers abandoned the breeding of golden apple snails one after another. The abandoned golden apple snails gradually spread to fields, canals and other places.

In the Americas, where the golden apple snails are native, although they reproduce just as quickly, they do not become a disaster because there are local predators such as snail kites (Rostrhamus sociabilis) to help control their numbers. However, the people who introduced the golden apple snails did not consider this problem at all. In the few years after their introduction, the golden apple snails, which had no natural enemies in the local area, quickly became a disaster . The golden apple snails, which have a more diverse diet, use various rivers, ponds and rice fields as their bases, eating almost any plant they can touch.

Snail Kite｜Dario Sanches / Wikipedia

The damage caused by golden apple snails first manifested itself in the rice farming industry. The hungry golden apple snails gnawed on rice, causing a reduction in rice production. In addition, golden apple snails also attacked citrus fruits, water chestnuts, sweet potatoes, arrowheads, astragalus, and aquatic vegetables in humid habitats, causing an ecological disaster.

How to distinguish between golden apple snails and field snails?

The golden apple snail is the intermediate host of parasites such as Angiostrongylus cantonensis and Echinostoma volvulus. A golden apple snail can contain 6,000 parasites . Eating insufficiently heated golden apple snails may cause parasitic infection, which can lead to coma and death in severe cases. So how do you distinguish between golden apple snails and field snails?

The "field snails" we usually refer to are generally the Chinese round field snail (Cipangopaludina chinensis) or the Chinese round field snail (C. cathayensis). These two types of field snails are widely distributed in my country and can be found in almost all lakes.

The golden apple snail and field snail look very similar, and it is relatively easy to distinguish them if they are in their shells.

Firstly, the size of the golden apple snail is larger than that of the field snail , and the mouth of the snail is also larger than that of the field snail; secondly, the shell of the golden apple snail is yellow, while that of the field snail is bluish-brown; finally, the "butt" of the golden apple snail is flat, while that of the field snail is pointed.

The difference between the golden apple snail and two common field snails, the Chinese round field snail and the Chinese round field snail｜Claude & Amandine EVANNO

But if it is in the state of being shelled and processed, it is indeed difficult to distinguish. This also requires government departments to strengthen supervision, rather than just relying on the sharp eyes of consumers. After media reports, the Hanshou County Market Supervision Bureau in Hunan Province announced that it had closed down the company involved in selling golden apple snails as field snail meat.

However, no matter which type of snail it is, it may be the intermediate host of the parasite and can only be eaten safely after being fully cooked.

Author: Sundayhao, berlika

Editor: Calendar Girl, Yellow Line Pollock