I met a stranger one morning. I call her Rosy. Some might call her The Plague or The Pestilence or more accurately, The Destroyer of Dawdlers. Let me introduce you to her.
That’s Rosy’s look of consternation. She displayed it each time I moved her. Or when I got too close. Or when I took a profile shot, something she hates because it makes her look translucent. She thinks opaque is more her style.
Rosy’s a little tiger. Actually, she’s more a wolf—a rosy wolfsnail (a.k.a. cannibal snail; Euglandina rosea). She’s native around these parts. In fact, she’s endemic from Latin America into Texas and east along the Gulf of Mexico to Florida. She even has a minor presence from Georgia to North Carolina.
I discovered Rosy on my patio. She was hunting these:
No, she wasn’t hunting my hand. Silly, silly people… She was hunting the tiny baby snail I’m holding. Several dozen of these minuscule mollusks had climbed my patio fence to seek shelter from the rising water created by severe storms.
As I investigated the scene, I found Rosy searching for prey at the bottom of the fence. I promptly decided she needed her portrait taken. So I fetched her from the damp earth and put her atop the wooden latticework where I could more easily snap a few images—or at least where I could take pictures without having to kneel under a tree during a thunderstorm.
Rosy happens to be a voracious predator. She and her ilk have endangered and wiped out native snail species around the globe where she’s been introduced. Why did we provide free first-class air travel to exotic locales, plenty to eat both on the way and upon arrival, and lots of siblings to play with once she reached her various destinations? In feeble attempts to control the likewise introduced East African land snail (a.k.a. giant African land snail; Achatina fulica). We humans are so daft, are we not? That idea was akin to dowsing a fire with gasoline.
Like wolf spiders and their canine namesakes, she gets her moniker by actively chasing down and overcoming prey. Obviously she’s chasing other snails, otherwise she’d be an evolutionary failure. She moves at a snail’s pace while looking for clues that will lead her to lunch: the mucus trails left behind by snails and slugs. Once she finds such a path, she no less than doubles her speed to catch up with the unsuspecting critters. And under the best circumstances she moves five times faster than other snails. She’s the hare to their tortoise, albeit one that remains painfully slow from our much larger vantage.
Rosy is nicknamed the “cannibal snail” not only because she eats other snails, but because she has no problem eating her own species. It’s common for hatchlings of her kind to seek out and consume smaller or slower siblings. Late bloomers are toast. But later in life she’s less inclined to eat her own and more inclined to mate with them. You see, she’s a cross-fertilizing hermaphrodite: she can do the dirty with any other wolfsnail, and that can result in one or both individuals becoming pregnant. Usually, though, the smaller one gives up the goods to the larger one and lets her play housewife on her own.
Rosy is an equal opportunity huntress: she takes out snails of any size. She can manipulate larger snails into positions that allow her to nibble their tender bits, and her body shape empowers her to reach into their shells to fetch the next bite. Yes, she does have a slender figure, does she not? And unlike we humans, she maintains that figure no matter how much she eats. (It’s okay to be jealous.)
But Rosy needs to consume snails whole if she’s to continue expanding her own domicile. She metabolizes the homes of others and recycles the shell material for her personal building efforts. Hence she failed to control the African snail she was introduced to kill. To keep growing, she ate more of the smaller native snail species than she did the larger invaders. Oops!
She’s been introduced in places like Hawai’i, Japan, Guam, Madagascar, Sri Lanka, Bermuda and at least a dozen other places. What a horrible mistake. Instead of doing what we wanted her to do, Rosy set about causing the extinction of other snail species whilst pretty much ignoring the job description we’d laid out for her. She can be rather contrary.
She’s also a prolific breeder. Rosy can multiply her numbers up to five times more quickly than most of the snails she hunts. Mind you, her own cannibalism somewhat tempers those numbers, but her adaptability and her proclivity to procreate at high volume means she’s a menace in ways our silly ape minds never imagined when we begged her to clean up the other messes we’d made.
Rosy can grow to be a large gal. A few years ago I found one of her ancestors on my patio who was about five inches/12 centimeters long with a shell about three inches/seven centimeters long. That version of Rosy later perished of a self-inflicted shell wound after falling off the patio wall. Very unfortunate…
After our little photo session, I let Rosy go. Well, her and Rosy 2.0, the second wolfsnail that sneaked up on us while I was entranced by another shiny bauble that caught my eye. (It was a mushroom, damn it, if you must know. Like a ferret, I’m easily distracted by the next trinket, the next sparkly thing. So sue me.)
Since Rosy and her kith and kin are native to my area, I felt no shame in releasing them so they could continue their search for breakfast. Meanwhile, I grabbed a bit of puddle water and rubbed down the base of the fence. To give the baby snails a chance.
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One thing that makes Rosy so unpopular is that she ranks #35 on the Top 100 List of Invasive Species. She’s responsible for causing the extinction of all native tree snails in French Polynesia. She’s also done in most of the native land snails in Hawai’i. And that’s just two of the many places where she’s been introduced.
Rosy’s designation is that of a terrestrial snail. While taxonomically that’s correct, no one told her about the limitation. Fast on the ground, she’s also fast in the trees and underwater. She didn’t exactly sit at the base of trees in French Polynesia tapping her pseudopod waiting for lunch to come to her. She climbed those trees and ate the snails she was hunting. Likewise, she has no problem following and consuming lunch below the surface of aquatic habitats. Did I already mention she’s an equal-opportunity killer?
But even monsters like Rosy come from a place where they’re native, and destructive critters like her don’t lose their homeland beauty simply because we’ve let them loose in places where they promptly devastated the local ecosystem. Remember this: She didn’t swim to Japan or Madagascar or Hawai’i, and neither did she hitch a ride to those places unbeknownst to us. We took her there, along with a bunch of her friends and family, and we set her free.
Mind you, had I photographed her in any of the places where she’s wiped out or endangered a great many native species, the tone of this entry would have been a wee bit different.
[cross-posted to The Clade]