The "Massacre" Caused by Snails

 　　The giant African snail is one of the most threatening invasive creatures, and its feeding ability is astounding. Once plants cannot meet their needs, they will feed on sand, gravel and cement, and sometimes even destroy human buildings, causing huge economic losses.

　　I don’t know if you have heard such a story. I heard that eating raw snails is very nourishing, so my husband carefully fed several large snails with vegetables in his garden, ready for the whole family to enjoy. However, the price of the delicious delicacy is unbearable. Soon, the family developed fever, severe headache, vomiting and other symptoms. In the end, the husband and wife, the eldest son and the husband's mother died, and the second son died after more than ten years in bed.

　　Such an accident, which can be called a "family massacre", may have made many people know the cute and honest-looking African giant snails - they are the "well-fed big snails" in this story. They always carry tan snail shells with yellowish stripes. This giant snail can grow up to 20 centimeters, making it the largest snail in the world and one of the most threatening invasive creatures.

　　How good is the appetite of the African giant snail? The

　　African giant snail's body, feces, and even the surface mucus carry a large number of bacteria and parasites. And the real culprit behind the annihilation story at the beginning is the most common parasite in the African giant snail, Angiostrongylus cantonii.

　　Both humans and animals can become infected with Angiostrongylus cantoni after exposure to snail mucus, eating raw (or undercooked) parasite-infected snails, or vegetables contaminated with snail mucus. Once it enters the human body, it may invade the brain through the central nervous system, causing symptoms such as fever, headache, neck stiffness, nausea and vomiting, and even death in severe cases.

　　If the African giant snail as a "porter" of bacteria and parasites harms humans unintentionally, then its damage to the environment is "intentional".

　　The large African snail has a very good appetite, and its diet includes not only many crops of economic value to humans, such as cauliflower, papaya, bananas, etc., but also lichens, fungi and other snails (usually the carcasses of other snails).

　　Carefully observe the process of eating snails, you will find that although they move slowly, they are absolutely standard "dry rice snails" when they eat. In areas plagued by giant African snails, residents grow vegetables in their gardens that are sometimes eaten overnight.

　　Surprisingly, snails are actually the creatures with the most teeth in the world. In its pinpoint-sized mouth, there are more than 20,000 teeth densely arranged on the band-shaped tongue, so their tongues are called dengues. . In fact, snails can't "gnaw", they can only use the teeth and tongues of "grinders" to scrape the food down.

　　Even so, the feeding ability of the African giant snail is astounding. Not only can they eat soil, they can even lick and digest cement. Because they need constant calcium supplementation to maintain the growth of the huge hard snail shell on their backs, they usually consume a lot of plants to get calcium. Once plants cannot meet their needs, they will feed on sand, gravel and cement, and sometimes even destroy human buildings, causing huge economic losses.

　　Survival and reproduction

　　However , the destruction of the environment is only one of the self-cultivation of invasive species, and strong survivability in the invasive area is also a necessary condition.

　　As can be seen from the name, the natural habitat of the African giant snail was originally in warm and humid Africa. But if the environment is too dry or cold, they can slow down their metabolism by burrowing soft parts into the soil for as long as 5 to 9 months. Sometimes they also secrete a milky mucous membrane to seal the mouth of the shell, "closing the door" for themselves. Combined with their not picky eaters, the African giant snails brought to warm regions can be described as a duck to water.

　　In addition, African giant snails usually have reproductive function when they grow up to 6 months, and it is a hermaphroditic, allogenetic species. This means that each snail does not have to look for the "other half" of a specific sex, as long as any two sexually mature snails meet, they can reproduce. Studies have shown that under ideal conditions, a large African snail can lay thousands of eggs in its lifetime, and the survival rate of offspring is close to 90%, which shows its strong reproductive ability.

　　Invasion and extermination

　　Due to the preference for warm climates, the African giant snail is usually distributed between the Tropic of Cancer.

　　According to the Florida Department of Agriculture and Consumer Services, after the giant African snail was first discovered in 1969, Florida spent nearly $1 million to kill more than 17,000 snails, and finally announced the eradication of the invasive species in 1975. However, in 2011, another large African snail was discovered in Florida, which started a decade-long killing. This time, it cost about 23 million US dollars to kill hundreds of thousands of snails, and finally announced in 2021. Killed successfully. Unfortunately, in June of this year, a large African snail was found again in Florida, and it was forced to start the third "snail war".

　　It can be said that Florida has a lot of experience in fighting African giant snails. The staff sprayed the insecticide metaldehyde for snails to achieve targeted killing. They even trained Labrador retrievers, which can sniff out giant African snails, to track them during the night when the snails are most active. In addition, although the snails themselves move very slowly, they can use the mucus to attach to moving vehicles, garbage, etc., and move around. Therefore, it is crucial to set up an isolation area and strictly check the soil, machinery, etc. that may bring snails out of the isolation area.

　　In order to completely eradicate the giant African snail, humans can be said to have tried their best, but the giant African snail is not aware of the harm it has caused to humans. In fact, aside from the mating process, they are solitary throughout their lives, neither communicating with their peers nor forming any bonds with their offspring. Their lives are either moving, eating or resting.