Slugs slime into Oakland

They’ve appeared in Oakland for about four years, living as if they’ve never… They’ve appeared in Oakland for about four years, living as if they’ve never lived before — a hedonistic lifestyle. On cool summer nights, they can be found hanging out on porches or cruising the streets. They dwell in old, cracked buildings and don’t mind clutter. When it comes to food, they’re not picky. And with beer, they’ll have whatever someone is willing to buy them. The bittersweet indulgence can be a costly one because if they have too much … plop. They’ll drown.

It’s hard not to consider a Limax maximus one of the guys or gals — or both. The Limax maximus, meaning “great slug,” is the largest known slug in Pennsylvania. They love living in cities and can be found all over Oakland. They can grow up to about 6 inches long and are known for their leopard-like spots on their grayish-brown skin. The leopard print gives the Limax maximus its common name, “leopard slug.”

Tim Pearce, head of the Section of Mollusks at the Carnegie Museum of Natural History, believes there are more slugs this year because of the heavy snow this past winter.

“Most of the mollusks in our area have antifreeze, so they can stand temperatures well below freezing and still be alive. They would crawl underneath the ground where it stays warmer. When we have snow like we did this past winter, that snow acts like a really nice blanket,” Pearce said. “I personally have more slugs in my garden this year.”

Leopard slugs start becoming visible in May and stay out until the fall. These slugs like to hide in cracks in houses and sidewalks when it’s too hot and dangerous for them to be outside.

“Slugs are like leaky bags of water trying to survive on dry land,” Pearce said.

Leopard slugs are found in many states, but they’re mostly in port cities and states along the east coast.

Pearce said most garden slugs, like the leopard slug, are invasive species from Europe. The leopard slug was first discovered in the United States about 150 years ago. Pearce said they likely traveled to North America on merchant ships in the soil and rocks the ships used as ballast. The merchants would dump the dirt onto the North American soil, fill their ships with goods and head back to Europe.

Pearce and his friend Paul Robb, who is a collections assistant at the Carnegie Museum of Natural History, disagree about whether the leopard slug is a pest.

“It’s been here a long time,” Robb said. “As I like to say, I think it’s time it gets its citizenship papers.”

Since the leopard slugs are city slugs, they have little interaction with native slugs. But Pearce believes these slugs are detrimental to humans and the economy because they eat cabbage, kale, bok choy, hostas and other plants.

“I’m going to let the vegetable plants live, and I’m killing the weeds. We do play God. We do decide who lives and dies. I have chosen to favor the native species in a land,” he said.

He continued to say that just because there’s no evidence of the slug harming natives doesn’t mean it’s not happening.

Pearce and Robb agree that the leopard slugs are aggressive.

Robb used to raise leopard slugs, and he has seen their ferocity first hand.

“There were numerous instances when I saw the dominant slug just haul off and bite its cagemates. I remember one instance. I felt really sorry for this Limax maximus. He was sitting out without a shell. I had an overturned shell that provided shelter for them. It was just sitting out. I felt so sorry for him. I guess the other slugs had pushed him out. This poor, forlorn slug crawled back under the shell. Then, all of a sudden I saw the other two leopard slugs that had been under the shell bolt out in 90-degree directions from each other. And here this guy in the overturned shell was biting the hell out of them,” he said with a chuckle.

Robb has been bitten several times. Though the slugs didn’t draw blood, the nibble was startling. Slugs and snails have hundreds, if not thousands, of tiny teeth arranged in rows. They also have four tentacles, two top tentacles with eyes on the ends and two bottom ones for smelling and tasting.

Pearce joked that maybe the slugs were trying to mate with Robb’s finger.

Battle of the sexes — slug style

Though he’s never spotted a leopard slug, CMU senior Evan Korol has seen a video on YouTube of two leopard slugs mating. A friend, who shared Korol’s interest in the television series “Planet Earth,” sent him the link.

“It’s one of those awkward things, but it’s sort of beautiful,” Korol said.

Though leopard slugs are hermaphrodites, like most slugs, they still mate. Mating for the leopard slug, however, is a particularly taxing act. A BBC video narrated by Sir David Attenborough explains that a slug advertises its readiness to mate by changing the taste of its slime. When a willing partner catches on, it will find the other slug. They travel up a tree, stair case or other structure and twist their bodies together.

Then they slip down a thread of mucus. While suspended in the air, the leopard slugs’ light blue male organs emerge from the right side of their heads, and they intertwine. The male organs fan out, and sperm passes from one slug to the other.

Pearce has only seen the leopard slug mating spectacle once.

“I saw it when I was in the fifth grade, way long ago, before I even knew what sex was about. It was an amazing thing, and so it stuck with me,” he said.

Pearce believes that sperm passes both ways when leopard slugs mate. They both deposit sperm into the spermatheca, which is a female reproductive organ and digestive tract. He believes that this organ consolidates the male and female desires of a slug.

“[A slug] wants to be promiscuous, but it wants to be choosy. Promiscuous. Choosy. What does it do?

“So they say, ‘Oh sure, I’ll take your sperm. Here, you have some of mine. I’ll take your sperm, and then I’m just going to digest it,” Pearce said with a hushed, sly voice.

It’s uncertain whether leopard slugs can self-fertilize. Proof would require a virgin slug to lay eggs, which hasn’t been documented.

Little definitive research has been done on the leopard slug, Pearce said. He, however, encourages people to study and grow compassion for mollusks.

If you get slug slime on your hands, it’s best to scrape it off with a paper towel before washing your hands. The slime absorbs the water and becomes slimier. Leopard slugs make nice pets, but if the keeper grows tired of the slugs, Pearce urges the keeper to euthanize them or let them live out the rest of their lives. Leopard slugs can live for four years, but they tend to live shorter lives in captivity. They shouldn’t be reintroduced into the wild because they can alter the local ecosystem.

Pearce sometimes holds slug races between different species of slugs to entertain and educate youngsters. The setup for a slug race is a circle within a circle. The slugs start in the inner circle and must travel the 8 inches to cross the outer circle.

The races aren’t always exciting, though.

“The fastest I’ve ever seen a slug run those 8 inches is a minute and a half, but I’ve run races that have run for 20 minutes, and no one has won,” Pearce said.

Ounce for ounce, the leopard slug isn’t the fastest. But when it comes to slug races, size matters. So, in a slug race with native species, bet on the gladiator, the great one: Limax maximus.