Ambient Light Impact on Snails

[Razorbacks]

I wanted share a recent learning. I noticed my new Trochus snail had not moved much for 10 days. It moved enough to let me know it was alive, but everyday it was in the exact same spot and I have not noticed any real change in algae since adding so didn't seem to be eating a lot.

I checked on it around 10pm last night expecting to see it moving, but it had not moved at all from where it was during the day. However, I also noticed just how many items I have for the aquarium that put off light. The tank had a decent glow to it despite the actual tank and room lights being off. Most noticeably my newly purchased wave maker was putting out tons of light for a small device with only a basic digital display.

I flipped that over which cut the light significantly then I put a few pieces of tape over my green "on" indicators for for the wavemaker and light outlets. The SECOND I did this the trouchus started moving and went much further from his normal location than I had ever seen. Not only that, but this morning it was resting in a totally different spot which is the first time in 11 days.

While I know snails are nocturnal, I can't find references to people having similar issues so I thought I would share. I believe this helped my cerith snail too because I saw it shortly after the change as well, but not before. His movement is much harder to keep tabs on since he usually burrows to sleep.

 

[ISpeakForTheSeas]

I'm curious to see if anyone else has noticed something similar, as I know lights on at night can have a huge impact on a lot of critters in the wild.

Also, just as a note here on snail sleep/activity patterns:

My understanding is that most sea snails (conches included) don’t really sleep based on the day/night cycle (though they are still considered nocturnal) - they sleep about 7 times in 13-15 hours, then go for about 30 hours with no sleep. My understanding is that it’s generally just safer for them to go around at night or their prey is more active at night, so they usually prefer roaming at night. If I’m not mistaken, even if they’re not actually sleeping during the day, they’re relatively likely to just stay put until the lights go off for those reasons.

A supporting reference with slightly different numbers than those in the quote (they list 37+/- 4 hours of activity in the study below):

Behavioural evidence for a sleep-like quiescent state in a pulmonate mollusc, Lymnaea stagnalis (Linnaeus)

SUMMARYThe objective of this study was to determine whether the great pond snail, Lymnaea stagnalis, expresses a sleep-like behavioural state. We found that snails spontaneously enter a relatively brief (22±1 min) quiescent state characterized by postural relaxation of the foot, mantle and...

journals.biologists.com