Aliens with voracious appetites are invading Florida, and they're leaving nothing behind but a thickly layered trail of gooey slime. They're not from another planet, but they're not from around here either: giant African land snails.

"They're huge, they move around, they look like they're looking at you ... communicating with you," described Denise Feiber, a spokeswoman for the Florida Department of Agriculture and Consumer Services, to the BBC.

Florida is no stranger to invasive species, but these giant snails might be the most destructive of them all. They can grow to a whopping 8 inches long and their shells are so thick and sharp that they can pop car tires. When they encounter lawnmower blades, the shells turn into projectiles. Most distressing of all, though, is their appetite. They devour "pretty much anything that's in their path ..." according to Feiber. The snails are even known to eat through plaster walls.

The good news for people is that the snails are vegetarian. The bad news is that they feast on more than 500 different plant species, endangering a wide variety of native flora and threatening agriculture throughout the state.

There's also the slime and excrement, which coats the walls and pavement wherever these creatures lurk. Oh, and they are known to carry disease — a parasitic rat lungworm that can potentially cause meningitis in humans.

Since their arrival, the snails have spread at an expeditious rate. More than 117,000 have been caught in Miami-Dade County alone, and the pace of capture is now at more than 1,000 a week. Part of the reason for their rapid distribution is that Florida represents an ideal climate for the species. Of course, it doesn't help that a single snail can produce more than 1,200 eggs a year. They can also live for as long as 10 years.

It may seem unlikely that an animal like this can be kept as a pet, but the reality is that their size and curiosity make them popular in the pet trade. An irresponsible pet owner is probably to blame for originally releasing the snail into the Florida wilderness.

The snails emerge en masse from underground hibernation every year for the rainy season, and officials expect this year's infestation to be the worst yet. There is now even a Giant African Land Snail Science Symposium, where possible eradication tactics are considered. Stronger bait was approved this year, but the snails are a resilient species. Before long, the only thing thicker than Florida's notorious humidity might be the slimy trails left behind by these invasive snails.

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Bryan Nelson ( @@brynelson ) writes about everything from environmental problems here on Earth to big questions in space.

Giant snails invade, coat Florida in slime
Giant African land snails, an invasive species on the march in Florida, can grow to 8 inches long and eat through plaster walls.