Do snails need sunlight?

[starcrazy19]

Hi everyone,
Does anyone know if snails need sunlight to be healthy? I've found in the cold weather that covering my tanks with blankets helps keep the heat & humidity up. But I've started to worry a bit that they won't be getting any natural light... Barely any light at all infact. But they sleep in caves/burrowed underground anyways... Does sunlight matter to their health or time regulation? Thanks!

[malacophile]

I've wondered about this, myself. In most animals, vitamin D from sunlight is critical for the proper metabolism and utilization of calcium, as well as the proper function of many biological processes. However, the necessity of it for snails seems questionable. They're usually nocturnal, and when they do come out during the day, many of them are on the forest floor amongst an abundance of shade.

I'm now wondering if this may be why slugs and snails love fungus so much. Mushrooms naturally contain vitamin D, which would be about the only way slugs and snails could get that particular nutrient if they're largely nocturnal.

[Baron S]

To live healthy lives in captivity? I'd say it is not necessary. Their day to day activity, I strongly suspect, would not suffer for it.

That said, they do rely on photoperiod cues for very specific functions. I know that reproductive maturation in many gastropod species is reliant on the amount of natural light provided by the current season, in part. Also, natural light almost undoubtedly plays a role in cold hardiness preparation from year to year.

Since your snails enjoy a stable residence, ostensibly free of sub-freezing temperatures, you probably don't have any reason to worry that you'll mess up their biological workings.

[pinkunicorn]

I posted about this a good while ago, with a link to a nice article about the sunlight requirements of tree snails. Those guys actually die without UV light access. The article was about trying to breed the threatened tree snails in laboratory and the author's snails just dying all the time until he thought about the sunlight factor. And with UV lamps he got the snails to thrive. Tree snails spend a good part of their day in the canopies exposed to the sun, so it makes sense!

As for other snails... that's a bit trickier. I (and a few others on the forums) have noticed at least aspersas get a "tan". My wild caught individuals are a lot darker than captive borns, and even WCs lose their dark colour fading into creamy toffee after a good while in captivity, especially in the winter. Whether this is relevant to their health or not I don't know. I have tried to give my tanks sun exposure in spring/summer/autumn just in case, though. I take the slimers to hang out with me if I'm sitting on the balcony, too. Not daily but a few times a week. Land snails that typically roam during the night and try to stay in the shadow likely don't get that much sun exposure in the wild, just a little. And slugs...well my slugs actively avoid sunlight, they will slime on the other side of my hand to shadow immediately if exposed to the sun.

But if you happen to have the (red-listed and highly vulnerable) tree snails do give them regular UV light exposure, else they WILL die.

[starcrazy19]

I diddn't even realise it was possible to get those rare and brightly coloured tree snails like polymita picta in captivity! I suppose some people must live in proximity to them so can go and collect them... I'd be surprised to know there were any at all in the UK though

Anyway my snails are gals so hopefully, won't mind the dark too much. I think I will try and encourage them to come out on the windowsill and see some daylight when the weather gets warmer, but I live in the city on a busy junction and wouldn't take them outside, the petrol fumes give me a bad enough time!

I will go look for your post pinkunicorn and see what more I can learn Thanks!

[pinkunicorn]

Well, you're not really supposed to have them as they are critically endangered, but some people do conservation breeding to help the populations stay alive and some even illegally end up with a snail without knowing what to do with it...

I think it was in the Announcements or some other odd forum for that kind of question and it was about Liguus snails, if you want to search the forum for it. I was going to look up the link myself later, but if you get there before me search for Liguus tree snails!

[Katie]

I'm sure there was a thread a couple of years ago either here, or over on Supersnails, about the benefits sunlight can have on captive snails. I'll see if I can find it.

Edit;
Can't find the thread I was thinking of.. may have imagined it haha, but this thread mentions something about whether sunlight will benefit shell growth:

petsnails.proboards.com/index.cgi?action=display&board=growth&thread=9522&page=1