How do slugs and snails know where the plants are?

[Herbsandveg]

Whilst pottering about in my garden today, I noticed 7 or 8 large snails starting to feast on a few seedlings in several of our large pots. Now, the thing is that these pots were upwards of 2ft off the floor from base to rim, and the seedlings have grown only in the pots since being sown in there as seeds just two or three weeks ago. To a snail or a slug the height required to scale the pots to get in and at the plants must be on the same scale as us humans climbing up a very tall building or other structure. So how do they know there's actually anything in the pots? Why, for example don't climb other structures to try to see what might be in the there, and even allowing for the fact that they might sometimes actually do that (thus making several pointless journeys, do they 'instinctively' know which pots have plants in them given that the seedlings aren't yet visible from ground level? This one really puzzles me, and I'd be fascinated to learn the explanation for this very strange phenomenon...

[stelladays]

That's some thing i have always wanted to know, it like they can smell them, saying that i found a snail on a metal clock that i had put on a wall 10ft in the air no plants in sight, good to see what people come up with

cheers

[Rocketron]

Pheromones I would imagine.

[rustylady]

Snails are bu@@ers for climbing. I've found them climbing my plum tree, about 7 feet above the ground.

[Linzy]

Now for a good few years know since getting into gardening i have observed slugs and snails in the garden and i have been able, from these observations noted a few things. The first is when ever i find a slug snail there is another close to hand. I think that this is a garden committee meeting discussing where they have found the latest tasty edition to there menu. Now also they quite often seem to follow one another so i pretty sure the slugs can remember where plants are and they show the other slugs where to go. My other thought is those little antenna bits they have, is actually emitting a sonic signal to inform others of the whereabouts of tasty food, like dolphins. Im thinking that they are building a secret intelligence and are out about to take over. So unless doctor who arrives in his tardis to disrupt the Sonic signal, ive no choice but to salt the little bleeders.

[alldigging]

Had you watered them?


I've been and chopped lots of them up this afternoon and will be popping back out in a bit to do some more.

[Herbsandveg]

Had you watered them?


I've been and chopped lots of them up this afternoon and will be popping back out in a bit to do some more.

The rain had watered ours...

[rustylady]

The rain had watered ours...

Get chopping and stomping then. Or drop them in a bucket of salty water.

[snohare]

Had you watered them?


I've been and chopped lots of them up this afternoon and will be popping back out in a bit to do some more.

Oh no !!! They're just like couch grass and ground elder...the more you chop them up the more you will have...and watering just makes it worse ! They'll be popping out like Gremlins...
I mean, stands to reason, dinnit ? Explains a lot.
I actually know a bit of sciencey stuff about slugs and snails, courtesy of a New Scientist article that stuck in my mind.
The slime trail they leave is actually directional; any slug crossing it will be able to tell which direction the trails "goes" in, whether or not the slug making it had just been fed or was hungry, how long ago, etc...and this information network is so important to them that even when starving, they will devote much of their metabolic resources, and particularly calcium, to laying down (and reading) these trails.
So they basically don't need a memory or the ability to learn, instead they have a set of reflexes which just tell them which way to go when they meet a trail; and because of the information encoded in the slime, the experiences of all the other mollusca whose paths they cross are available to each individual.
Funnily enough, the military are spending megabucks on tiny drones and spy bugs that can be released in swarms, and will do the same sort of reconnaisance electronically, with the occasional one that sends the accumulated data home. It's called distributed networking, and it is incredibly efficient, but the rules of how to organise the reflexes are very complex mathematically. Really complex.
Slugs and snails of course have been practicing for a long time - since shortly after life came out of the oceans, which is more than a billion years ago - and they have a very good quality control system. The slugs which find themselves ten feet up a wall on a clock, don't come back...
Reassuring to know that they don't have effective time travel, or they really would have taken over the world by now !

Oh yes, the little wiggly bits - all four of them - are eyes. Two of them only come out when they feel safe, the other two are lower quality and more disposable.

[mothhawk]

Yes, snails can smell plants, and they like leafy greens which are rich in calcium, so they can grow good strong shells.

eta that's amazing info Snohare, I guess that's why you find half a dozen all crammed under the same stone, they've latched onto a trail and followed the snail in front.

[alldigging]

The little ones are really tricky to get with secutuers.
Hahahahah hahahahah
But not impossible.
Snails crunch really nicely.