The giant African land snail, according to invasivespeciesinfo.gov, was first introduced to Hawaii in 1936 because they were imported for educational purposes, as pets or in cargo. Since then, it has become an invasive species and an agricultural pest.
The United States Geological Services website describes GALS as being potential vectors of zoonotic pathogens, which means it’s possible for people to get sick because of germs and parasites carried by the GALS. One such illness is rat lungworm disease.
Rat lungworm disease, according to the Centers for Disease Control and Prevention, comes from a parasitic worm. The adult worms live in rats and pass their offspring onto other rats by infecting snails and slugs with larvae. The snails and slugs are in turn eaten by rats, which then get infected. It’s possible for humans to be infected in the same way the rat is infected.
Most people infected with rat lungworm recover without any symptoms, says the CDC website. However, in rare cases, it can cause eosinophilic meningitis, which is not usually fatal.
Another unintended consequence of GALS is the introduction of the rosy wolf snail to Hawaii. According to the Hawaii Department of Land and Natural Resources, rosy wolf snails were deliberately introduced in the 1950s in the hopes they would eat GALS, who were eating too many crops.
The rosy wolf snail, DLNR states on its Snail Extinction Prevention Program website, then went on to eat endangered native Hawaiian snails instead, driving some to extinction.
The DLNR website makes no mention of current targeted efforts to eradicate GALS in Hawaii. Originally, the snails were also found on the mainland United States, but Florida was successful in eradicating them in 2021.
GALS can get up to 8 inches long with a shell 4 inches across, according to a-z-animals.com, with the largest recorded snail being nearly 15 inches long. They live three to 10 years and can lay up to 200 eggs at a time. Their top recorded speed is 0.002 miles per hour.