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A beetle? In my aquarium I have snails walking upside down under the water surface!

dvdbloc 5y ago
Do they do this when you put food in the tank? Funny you mention it because I just noticed my snails doing this the other day… it sounds weird but I have engineers come to my house just to see it because they don’t believe it
- MrJagil 5y ago
  Do you have video?
  - pvaldes 5y ago
    Is pretty cool to see and all you need is a lamp. Aquatic snails walk under the surface all night. Some fishes vacuum the surface clinging upside down also.
krisoft 5y ago
Just to clarify: are your snails walking on the water-air surface upside down? Or they are underwater but clinging to some surface other than the water-air one? Assuming it is the first, do they breach the surface tension?
- enriquto 5y ago
  They cling to the water surface alone. They cling, they don't "stand" on it. Their whole shell and body is inside the water, and the shell hangs from the body, which is firmly attached to the surface. If I disturb the surface they fall to the bottom. This is a very common behaviour of pond snails. Just search "snail water surface" on google to see many pictures of it. The beetle seems to do the opposite thing, though. It is buoyant so it floats to the surface, on which it stands and walks with its legs as it would do on the ground. The air\surface interface is very strong for small critters.
  - krisoft 5y ago
    Thank you very much for the explanation. I didn’t know about this. Super exciting. For others who might be interested I found this video showing the behaviour: https://youtu.be/hOLbyAzLmbQ https://youtu.be/hOLbyAzLmbQ
  - jacksonkmarley 5y ago
    > The beetle seems to do the opposite thing, though. Why is it the opposite? From the description it seems exactly the same.
    - enriquto 5y ago
      From the point of view of the beetle, he's not walking upside down. Physical forces attract him to the "ground" (the underside of the water surfaces) and he just walks normally, as if he was affected by gravity instead of buoyancy. The snail is definitely "upside down", for the physical force (gravity) wants to separate her from the "ceiling" on which she clings.
      - jacksonkmarley 5y ago
        Aha, I get it, interesting point.
knnnuehu 5y ago
Snails dont have legs or limbs. And "walking" is a legged gait. Limbless loco is a seperate story -https://en.m.wikipedia.org/wiki/Terrestrial_locomotion#Limbless_locomotion https://en.m.wikipedia.org/wiki/Terrestrial_locomotion#Limbl... Snails are pretty cool though with their mucus turning everyting around them friction free so they are badically ice skating. Have no clue what happens in water though.
dtgriscom 5y ago
I'd believe that they could hang upside down with their feet at the surface. I wouldn't believe that they could actually propel themselves across the surface; any movement would be due to water currents.
- enriquto 5y ago
  They definitely propel themselves. Even if I stop the filter so that there's no water circulation, they can walk on the surface just as fast as they do on the glass (which is quite slow, but still). Think about it: water striders propel themselves quite fast on the surface of water, from the other side. The air/water interface is a though barrier to break for small beings. Thus they can use it for support, from either side.

Do they do this when you put food in the tank? Funny you mention it because I just noticed my snails doing this the other day… it sounds weird but I have engineers come to my house just to see it because they don’t believe it

MrJagil 5y ago
Do you have video?
- pvaldes 5y ago
  Is pretty cool to see and all you need is a lamp. Aquatic snails walk under the surface all night. Some fishes vacuum the surface clinging upside down also.

krisoft 5y ago

Just to clarify: are your snails walking on the water-air surface upside down? Or they are underwater but clinging to some surface other than the water-air one? Assuming it is the first, do they breach the surface tension?

enriquto 5y ago
They cling to the water surface alone. They cling, they don't "stand" on it. Their whole shell and body is inside the water, and the shell hangs from the body, which is firmly attached to the surface. If I disturb the surface they fall to the bottom. This is a very common behaviour of pond snails. Just search "snail water surface" on google to see many pictures of it. The beetle seems to do the opposite thing, though. It is buoyant so it floats to the surface, on which it stands and walks with its legs as it would do on the ground. The air\surface interface is very strong for small critters.
- krisoft 5y ago
  Thank you very much for the explanation. I didn’t know about this. Super exciting. For others who might be interested I found this video showing the behaviour: https://youtu.be/hOLbyAzLmbQ https://youtu.be/hOLbyAzLmbQ
- jacksonkmarley 5y ago
  > The beetle seems to do the opposite thing, though. Why is it the opposite? From the description it seems exactly the same.
  - enriquto 5y ago
    From the point of view of the beetle, he's not walking upside down. Physical forces attract him to the "ground" (the underside of the water surfaces) and he just walks normally, as if he was affected by gravity instead of buoyancy. The snail is definitely "upside down", for the physical force (gravity) wants to separate her from the "ceiling" on which she clings.
    - jacksonkmarley 5y ago
      Aha, I get it, interesting point.

knnnuehu 5y ago

Snails dont have legs or limbs. And "walking" is a legged gait. Limbless loco is a seperate story -https://en.m.wikipedia.org/wiki/Terrestrial_locomotion#Limbless_locomotion https://en.m.wikipedia.org/wiki/Terrestrial_locomotion#Limbl... Snails are pretty cool though with their mucus turning everyting around them friction free so they are badically ice skating. Have no clue what happens in water though.

dtgriscom 5y ago

I'd believe that they could hang upside down with their feet at the surface. I wouldn't believe that they could actually propel themselves across the surface; any movement would be due to water currents.

enriquto 5y ago
They definitely propel themselves. Even if I stop the filter so that there's no water circulation, they can walk on the surface just as fast as they do on the glass (which is quite slow, but still). Think about it: water striders propel themselves quite fast on the surface of water, from the other side. The air/water interface is a though barrier to break for small beings. Thus they can use it for support, from either side.