Are you a snail savant? I have questions! (NON-foodie edition)
November 11, 2014 11:26 AM Subscribe
So, we seem to have many snails in our outdoor area lately, and I've been observing them and have many questions...
The setting is our terrace and courtyard with potted plants (many! ranging from flowers, plants, and vines to largish trees), plus surrounding trees, vines, plants etc., from the neighboring houses, it's a very, very green space in the middle of a big city.
Here are the things I'm curious about:
what is going on in this image? I retrieved this leaf after watching a snail mulling / mauling around with it a bit, and then I went inside for a while, and when I came back the snail was gone, but I saw the outline of the snail had been "eaten through" the leaf, even including an outline of the tentacles (seemingly!), which isn't how I understood (just from brief googling) snails to eat/ingest. I'd call it coincidence that it looks like the outline of the snail, but I had just seen the snail wrestling with that specific leaf earlier. Do their whole bodies exude some kind of vegetation decomposing agent or something?
wtf department: I don't understand what snails are trying to do sometimes. I read that they have a great sense of smell, so why have I seen the following things: snails crawling up high sheer walls (stucco-like over brick) to places that have no vegetation at all; snails crawling up my front door (glass and metal) and lodging themselves in a curlicue of decorative wrought iron; snails crawling into ashtrays with cigarette butts – all of which I've seen several times, when in all cases there was easy vegetation, both fresh and decomposed, and much wetter spots without these sometimes epic efforts of the snail to go places no man has gone before.
Plastic fantastic, or super-smeller? I put a plastic grocery bag with broccoli in a shrink wrapped container outside temporarily because I didn't have enough room in the fridge, and a bit later saw two snails crawling on that bag. Was this because their super smellers smelled the broccoli under all that packaging and that was more inviting than all the tons and tons of green stuff easily available all around them, or were they for some reason attracted to the (white) plastic grocery bag? The bag was tucked all around and knotted, not open.
Touching heads; what are they communicating? Do we know anything about how snails communicate with each other? I saw two snails in the same area slowly slowly creep closer to each other, sort of touch heads / tentacles, and then each go on their own way. What did they say?
Sexy-sex snail style: I've read that snails are hermaphroditic, but what does this mean in practical terms? Do snails sometimes produce sperm and sometimes produce eggs, and it's just environmental in the sense of whatever is most needed under the conditions? Just random? Different phases? Or do they have the ability to contribute either way at all times?
Speaking of which: Despite seeing what seems to me to be an awful lot of snails recently, I've never encountered snail eggs. Are they buried or hidden in some way? Never ever seen 'em.
Don't be a stranger!: Why did they just suddenly appear in the last couple of years? Is it common / normal for snails to be extremely minimal and then sort of explode in population for a period? Or is it more likely that environmental agents make the difference?
Any other snail info for me? I feel like there are snail known knowns; there are snail things I know I know. I also know there are snail known unknowns; that is to say I know there are some things I do not know. But there are also snail unknown unknowns -- the ones I don't know I don't know. Can you help?
The setting is our terrace and courtyard with potted plants (many! ranging from flowers, plants, and vines to largish trees), plus surrounding trees, vines, plants etc., from the neighboring houses, it's a very, very green space in the middle of a big city.
Here are the things I'm curious about:
what is going on in this image? I retrieved this leaf after watching a snail mulling / mauling around with it a bit, and then I went inside for a while, and when I came back the snail was gone, but I saw the outline of the snail had been "eaten through" the leaf, even including an outline of the tentacles (seemingly!), which isn't how I understood (just from brief googling) snails to eat/ingest. I'd call it coincidence that it looks like the outline of the snail, but I had just seen the snail wrestling with that specific leaf earlier. Do their whole bodies exude some kind of vegetation decomposing agent or something?
wtf department: I don't understand what snails are trying to do sometimes. I read that they have a great sense of smell, so why have I seen the following things: snails crawling up high sheer walls (stucco-like over brick) to places that have no vegetation at all; snails crawling up my front door (glass and metal) and lodging themselves in a curlicue of decorative wrought iron; snails crawling into ashtrays with cigarette butts – all of which I've seen several times, when in all cases there was easy vegetation, both fresh and decomposed, and much wetter spots without these sometimes epic efforts of the snail to go places no man has gone before.
Plastic fantastic, or super-smeller? I put a plastic grocery bag with broccoli in a shrink wrapped container outside temporarily because I didn't have enough room in the fridge, and a bit later saw two snails crawling on that bag. Was this because their super smellers smelled the broccoli under all that packaging and that was more inviting than all the tons and tons of green stuff easily available all around them, or were they for some reason attracted to the (white) plastic grocery bag? The bag was tucked all around and knotted, not open.
Touching heads; what are they communicating? Do we know anything about how snails communicate with each other? I saw two snails in the same area slowly slowly creep closer to each other, sort of touch heads / tentacles, and then each go on their own way. What did they say?
Sexy-sex snail style: I've read that snails are hermaphroditic, but what does this mean in practical terms? Do snails sometimes produce sperm and sometimes produce eggs, and it's just environmental in the sense of whatever is most needed under the conditions? Just random? Different phases? Or do they have the ability to contribute either way at all times?
Speaking of which: Despite seeing what seems to me to be an awful lot of snails recently, I've never encountered snail eggs. Are they buried or hidden in some way? Never ever seen 'em.
Don't be a stranger!: Why did they just suddenly appear in the last couple of years? Is it common / normal for snails to be extremely minimal and then sort of explode in population for a period? Or is it more likely that environmental agents make the difference?
Any other snail info for me? I feel like there are snail known knowns; there are snail things I know I know. I also know there are snail known unknowns; that is to say I know there are some things I do not know. But there are also snail unknown unknowns -- the ones I don't know I don't know. Can you help?
I am also fascinated by the snails we get in out garden, which are copious in a wet summer or autumn. FYI you can take nailpolish and lightly dab their shells to see who comes back; it's very interesting!
posted by DarlingBri at 11:54 AM on November 11, 2014 [1 favorite]
posted by DarlingBri at 11:54 AM on November 11, 2014 [1 favorite]
OMG Is this where I get to bust out my limited knowledge of third grade life science standards??? YESSS
I have just one word for you: ESTIVATION. Whenever you find a snail stuck to some flat surface for an extended period of time, they're in hibernation and they've literally cemented themselves to that surface in hopes of enduring harsh weather (periods of high heat, mostly). If a snail does this wrong, or if their shell has any cracks in it, they can shrivel up and die rather than go dormant. This is usually the best time to get rid of them, but if you are a tender hearted person like me and my third graders, you could also build them little houses and make sure they get plenty of shade. I am told that polka dotted ones are best.
posted by Hermione Granger at 11:56 AM on November 11, 2014 [8 favorites]
I have just one word for you: ESTIVATION. Whenever you find a snail stuck to some flat surface for an extended period of time, they're in hibernation and they've literally cemented themselves to that surface in hopes of enduring harsh weather (periods of high heat, mostly). If a snail does this wrong, or if their shell has any cracks in it, they can shrivel up and die rather than go dormant. This is usually the best time to get rid of them, but if you are a tender hearted person like me and my third graders, you could also build them little houses and make sure they get plenty of shade. I am told that polka dotted ones are best.
posted by Hermione Granger at 11:56 AM on November 11, 2014 [8 favorites]
Snails mate by shooting one another with a love dart. I'm not kidding.
posted by Solomon at 12:16 PM on November 11, 2014 [2 favorites]
posted by Solomon at 12:16 PM on November 11, 2014 [2 favorites]
This is based on what I've picked up over the years so someone with a more scientific background feel free to correct me if I'm wrong.
Being hermaphrodites means that when they have sex they actually fertilize each others eggs, they don't so much play a male & female role during mating as both at the same time. They will both exchange sperm AND lay fertilized eggs afterwards. Which is kind of cool IMO.
posted by wwax at 12:17 PM on November 11, 2014 [1 favorite]
Being hermaphrodites means that when they have sex they actually fertilize each others eggs, they don't so much play a male & female role during mating as both at the same time. They will both exchange sperm AND lay fertilized eggs afterwards. Which is kind of cool IMO.
posted by wwax at 12:17 PM on November 11, 2014 [1 favorite]
Oh & if you want a fascinating video the snails "cousin" the slug has the most amazing/disgusting/wonderful mating ritual. a bit of a side note and off topic, but I've always wanted an excuse to share that video with someone else that might find it interesting.
posted by wwax at 12:21 PM on November 11, 2014 [2 favorites]
posted by wwax at 12:21 PM on November 11, 2014 [2 favorites]
Why not be your own cool aunt/uncle and get a nice book on snails? You could sit in the garden and read it.
OK, I see you're in Greece. Maybe there's something local?
posted by amtho at 1:16 PM on November 11, 2014 [1 favorite]
OK, I see you're in Greece. Maybe there's something local?
posted by amtho at 1:16 PM on November 11, 2014 [1 favorite]
Patriica Highsmith, she of Ripley fame, had a thing for snails. Wrote some creepy short stories in which they feature.
posted by IndigoJones at 2:50 PM on November 11, 2014 [1 favorite]
posted by IndigoJones at 2:50 PM on November 11, 2014 [1 favorite]
IndigoJones: And at least one novel! Deep Water's protagonist had two snails who are very much on love. I believe one is named Hortense.
I do think in some cases snails can smell through permeable plastic bags. On a different continent, I've found them all over the dog food container even though the rest of the porch was snail free.
posted by theweasel at 3:27 PM on November 11, 2014 [2 favorites]
I do think in some cases snails can smell through permeable plastic bags. On a different continent, I've found them all over the dog food container even though the rest of the porch was snail free.
posted by theweasel at 3:27 PM on November 11, 2014 [2 favorites]
What a nice question
posted by glasseyes at 5:27 PM on November 11, 2014 [4 favorites]
posted by glasseyes at 5:27 PM on November 11, 2014 [4 favorites]
This thread is closed to new comments.
That leaf looks like the snail's been eating the smaller veins. Juicier than regular leaf, but not as tough as the main vein.
"Up" is away from wetness. A useful rule of thumb if you only have a few thousand neurons. Plus lots of species like to eat the kind of plants and algae that grow on bark.
Plastic bags can be selectively permeable. You should set up an experiment - plastic bags with and without broccoli, glass jars with and without broccoli - which collect more snails? Pls report back.
Snail eggs are buried, and in clusters. I saw them after cleaning out a terrarium full of snails at the end of term when I was a kid. That's probably a good way to "capture" some snail eggs.
Homing snails - good citizen science project.
posted by Leon at 11:43 AM on November 11, 2014 [1 favorite]