Do slugs think?
This question is prompted by the following event.. When I place the days leave over outside for my nocturnal foxy visitor, I notice several slugs congregating where i put the previous evenings dish. If I then put it in a different place the following night the majority assemble there the night after, and so on.
Comments
Yes, slugs probably do think on some primitive basic level. Your experiment is invalid because the slugs may have only smelled the food.
But, that does propose an interesting idea for an experiment. When does thought take place? We can probably agree that an amoeba doesn't think and that a dog does a pretty good job of it, but can you train a slug? The Mythbusters (a show in the Discovery Channel) proved that you can teach goldfish tricks and they will remember them the next day so the idea of them only having a 6 second memory is a myth. Clearly, they can think and fish don't need to be too intelligent so where does the border lie?
For most philosophers it begins with the statement "I think therefore I am." One basic test for intelligence is if an animal can recognize itself in a mirror. Male deer have been known to charge mirror windows because they think they are looking at a rival. So how does that measure up to intelligence. It doesn't take a lot of intelligence to sneak up on a piece of grass, but it does take a little to be able to run away from predators.
I don't know how you can test your slugs for intelligence, but it is something to ponder they are about the same size as a gold fish, with maybe half the nervous system so do they have half the intelligence? And why can male deer be so dumb (no I don't think it is because they are male).
Next time try feeding the slugs with a plate of food and after a few times of moving the same plate around see if they go to an empty clean plate when you put that out. If they do then they might be remembering the plate as a source of food and so respond to the plate, thus making an intelligent connection.
To most people slugs aren’t worth much thought, I didn’t consider how intelligent or stupid they might be until you asked your question. But, they are creatures that share this planet with us and an understanding of them does lead to an understanding of us. For example when does the fetus start to think? Clearly, not at fertilization, but before it is born it can recognize music so at some point it develops intelligence. How big does the brain have to be to support intelligence? If a goldfish can be trained then we know that the fetus develops intelligence pretty early in its life, but after how many weeks? If a slug can think, with its primitive nervous system then a fetus starts thinking very early in life, much earlier than I would have assumed.
In saying a rifled slug you mean a rifled Foster type slug or Brenneke slug which are designed for smoothbore shotgun barrels were as most saboted slugs are meant to be shot from rifled shotgun barrels and usually have a smaller diameter bullet in the sabot. The rifled slug while bigger in diameter and heavier leaves the barrel at a lower velocity then the sabots and will loose velocity faster and about max range with a Foster type slug IMO is about 75yds maybe a bit more with a Brenneke. The saboted shotgun rounds use a lighter bullet with a smaller diameter so they leave the barrel at a higher velocity and retain the velocity more going down range. Plus there are some pretty hard hitting bullet designs in the sabots. The Hornady SST, Winchester Platinum tip and the Barnes Expander are just some of the heavy hitters out there. If you have a rifled slug barrel you can take advantage of them and have better accuracy and range. If you have a smothbore barrel the rifled slugs may do you better but one saboted slug I have shot well from a smoothbore is the BRI type which is packaged by Winchester. As far as fouling you will have powder fouling with both types but with the rifled slugs you may have some lead fouling and with the saboted slugs since they use a sabot you may have more plastic fouling.
I don't quite understand your description of events. If you put the food in place A on monday night and place B on tuesday night, on wednesday are the slugs at A or B. From what you've said I think they're at B, but since you're asking if they think they must be at A to have a conditioned response.
I think that in this instance the slugs are like cats and dogs who use their noses to find food. Slugs need food and they will use their senses to find it. And if they are at A on Wednesday night, maybe they're picking the very small leftovers away. They might prefer partially broken down food. Maybe they have learned that a fox will eat them too if they go to the dish too early? I doubt it though.
Time lapse photography of slugs living in an experimental enclosure shows that these animals can return to a homesite from over 90 cm by a direct route. Slime trail following and vision are not involved in this behavior. In the presence of a low velocity wind, homing occurs upwind. Surgical disconnection of the presumptive olfactory apparatus (digitate ganglion) from the central nervous system eliminates homing. Neurophysiological recordings from the receptor surface associated with the digitate ganglion and the olfactory nerve demonstrate the olfactory function of the digitate ganglion. The olfactory acuity and capacity for directed locomotion via olfactory cues are also relevant to studies of slug feeding behavior, ecology, and learning ability.
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That is a conditioned response. They go to the last place they found food. They have very tiny brains but they don't think like people. They think like little slimy creatures. Self preservation is first.
I guess you've just answered your own question.
They would not be able to knowingly return to the drop off place for food if they weren't able to think to remember the location and the relevence of returning there.
I don't think there's room for thinking neurons in their little brains. They wouldn't survive if they couldn't find food, so that sense is developed. But you don't need to think for that.
Yes they do the same as snails when they leave a slimy trail then go back on that slimy trail.
I like to think they think philosophy and new ways of governing societies.