"It's not spiders I dislike, just people." -Petra
Question #91315 posted on 05/31/2018 11:36 a.m.
Q:

Dear Alta,

What's the deal with *shudders* snails?

They're gross, they appear out of NOWHERE, some are big but some are little, and they just weird me out????

My main confusions that I would love clarification on:
1) where do they come from? do they reproduce or do they just spawn from Hade's Mansions? (I'm currently very convinced of the latter)
2) why do they bubble when you pour salt on them?
3) Are they useful for anything? Can we just... eliminate them entirely with no repercussions?

-Grossed out Guesthouse

A:

Dear Guesthouse,

Okay, have I ever mentioned on the Board that for years I had an irrational fear of snails (and that after answering this question that fear is definitely back)? It's like this question was perfectly crafted to allow me to talk about why snails freak me out.

So, first things first: How do snails reproduce? In a horrifyingly disgusting way, obviously. Most snails (with a few exceptions) are hermaphrodites, meaning they have both male and female reproductive organs. (Some can reproduce asexually, but most require another snail, as well.) For most species of snails, the process begins by the snails approaching each other and engaging in an hours long mating dance, eventually biting each other's "genital pores" located near their heads. Then they shoot their "love darts" at each other (I wish I were making this up, but this is the ugly truth, folks). Made of calcium, these darts aren't used for transferring sperm, and they don't enter the genital pore; they're literally little harpoons that the snails stab each other with. Although sometimes the love darts can actually harm the mate, they're coated with chemicals that increase the chances of the shooter's sperm fertilizing the other's eggs. After that whole debacle, the snails copulate by smashing their genital pores up against each other, mutually fertilizing each other. Both snails then carry their fertilized eggs for a few weeks before laying them in the top few inches of soil, where they wait for a few weeks before hatching. And to add just one more disgusting fact to this already appalling process, sometimes the recently hatched snails eat the unhatched eggs in their brood to give themselves more energy. So, basically they spawn from Hades' Mansions. For more reading about snail reproduction, see herehere, here, here, and here

Now, why do snails bubble when you pour salt on them? The short answer is because osmosis (8th grade me is very impressed/surprised that knowledge of osmosis is finally coming in handy). Osmosis is "the tendency of...water to pass through a semipermeable membrane into a solution where the solvent concentration is higher, thus equalizing the concentrations of of materials on either side of the membrane." Essentially that means that water can pass through cell walls (which are semipermeable membranes) to keep the concentration of a solute (something that dissolves in water, for the purposes of this question) roughly equal on both the outside and the inside of the cell. When we pour salt (a solute) on snails/slugs, it drastically increases the concentration of salt on the outside of the cell wall. That triggers osmosis, and water begins passing from the inside of the cells of the snail/slug's body to the outside, to equalize the salt concentration on both sides of the cells. Or in other words, pouring salt on snails literally sucks the water out of their body, and that's what we see bubbling up. Considering that water is a pretty important part of cells, this is highly unfortunate for the slug/snail being salted, because if their cells dry up and die, they dry up and die, too.

And now it's time for a few bonus questions about snails/osmosis!

First of all, why don't humans die of dehydration when we come in contact with salt? Basically because we have skin, which is much more impermeable than the cells inside our bodies (and the cells on the outside of snails' bodies). 

Secondly, how can we cook snails in salt without them turning into a puddle of osmosis-y goo? The process of cooking them changes the nature of the cell membranes, allowing water to flow both in AND out of the cell, as well as changes the nature of the proteins in the snails. 

Okay, now on to your last question—what is the purpose of snails? My personal opinion is that they only exist because we need to have opposition in all things, and snails certainly oppose the ideal of a perfect world, as well as my own happiness. Rating Pending talks about some of the parasites that snails serve as hosts to below, but honestly, none of those parasites seem like compelling reasons for why we should keep snails around. If anything, it seems like MORE motivation to somehow completely eliminate snails from the world. That seems impossible, though, and it probably would end up having a negative ripple effect on the ecosystem (as this article explains), so I guess we'll continue to suffer their existence. Also, snails really do play an important role in the ecosystem, eating dead plants that build up on the ground and serving as prey for other animals. 

Now that you and I both know more about snails than we ever wanted to, you may think this answer is over. Oh no. It was going to be, but Uffish Thought flagetted me and told me to look up videos of "snails eating worms and lizards for maximum terror," so obviously I have to link you to this Youtube video, in which a snail eats a gecko, and this one, in which a NEW ZEALAND GIANT SNAIL devours a worm in the most terrifying way possible. Because I have really great social skills (and also because misery loves company) I shared the video of the snail eating a worm at a bachelorette party this weekend. I'm a big hit in social settings.

In case you didn't click on the link, here's a screenshot of the snail eating the worm "like spaghetti," as the narrator says. You're welcome.

 Snail.PNG

-Equally Grossed Out Alta

P.S. Today I found out that one of my friends' first ever "pet" was a snail named Ponka. He captured it and kept it on a plate surrounded by a circle of salt so it couldn't escape. 

A:

Dear Gigi,

The deal with snails is that they are an important host for a number of wild and wonderful and terrible parasites. 

Schistosomiasis, caused by the parasites of the genus Schistosoma, is still a prevalent neglected tropical infection. Freshwater snails are invaded by the miracidia life stage and, after developing, the snails release cercariae, a free-swimming parasite stage, one that can penetrate human skin. They are moved around via the circulation until the end up in the liver where male and female worms mate (for life)(awwwww) and release eggs. These eggs are passed in feces or in urine.

In fact, Schistosoma haemotobium eggs end up in the bladder and can become embedded into the bladder wall and the need of the damaged cells to repair/replicate can end up causing bladder cancer, making S. haemobotibum a Class I carcinogen! And in other fact, an Egyptian mummy from 1189 B.C. was found to have S. haemotobium eggs in it’s urinary tract AND Egyptian papyrus describe urological problems that concord with S. haemotobium infections.

So that’s one deal with snails.

But I couldn’t talk about parasites and snails without going through the best, the most buck wild parasite life cycle I know of. (And you’d better believe it involves snails.)

The lancet liver fluke (Dicrocoelium dendriticum) is generally a cow parasite. But how does it get into the cow? Not easily.

First, parasite eggs are passed in cow feces. Who might be interested in eating some of that? Snails.

So now the snail is infected. It’s moving along leaving behind it’s trail of slime. And, surprise, somebody wants to eat that slime. Ants.

So now the ant is infected. The infected ant is, in most respects, fine. With one important distinction: it now has parasites that have migrated to its brain (specifically the subesophageal ganglion).

And now it’s the end of the day. What does an ant with parasite sitting in it’s brain want to do? Not go back down into the nest with the other ants. Instead parasitized ants climb to the top of blades grass, clamp onto the top and stay there all night.

If nothing happens, it climbs back down as the day starts to warm up. But night after night it climbs up and stays there until, sitting at the top of a blade of grass, a cow comes along and chomps it down.

And now the cow has parasites. It’s the circle of life.

The liver lancet fluke can also infect humans. So, you know don't eat ants. But as far as we know, the stage that comes out of the snail can't do anything to humans. So eat as much snail slime as you'd like.

- Rating Pending (who cuts now to a scene, deep in the ant colony, where a small ant detective is investigating her colony’s disappearing workers. “… She was telling me about this great snail slime she’d found yesterday, but then she didn’t come back last night! Something must have happened to her! Do you think it was an accident?” The ant detective adjusts her tiny hat, takes a drag on her tiny ant cigarette and shakes her head grimly. “This was no accident. It was just a fluke.”)

A:

Grossed Out,

Storrrry time: the part of the show when Babalugats tells a stupid story. 

Once upon a time I was a humble custodial worker at the MTC. I was just finishing wiping down the handrails outside 17m (dumbest job ever) when CRUNCH. But also SQUISH. I could feel both sensations under my foot simultaneously and it was not a small snail. The thing was YUGE. I actually almost cried because it was disgusting and I felt violated but also because I felt super guilty about killing the poor thing. Yucka. I can still hear it. 

Babalugats