How do slugs survive winters?

[Dumbledore]

I live in an area where it snows several times and gets cold in the winters, and I've seen multiple slugs in my backyard. I was wondering, how do they survive winters? I know that snails retract and make an epiphram (I know I spelled that wrong. ) but how do slugs survive, or do they just lay eggs underground, or what? Sorry, I'm just confused on this topic.

[inky]

I'm not exactly sure, but I think they hide away in small cracks to keep away from the rain and snow.

[wreckoning]

It's something not understood by science at this time, as far as I have read. We do know that slugs can and do survive canadian winters.

In regards to the eggs, they can survive the winter as well, which confuses me because aren't we freezing the eggs of slugs we don't have room for? In which case are we certain that freezing is really killing them? I plan to run some tests freezing eggs for different lengths of times and then seeing if they hatch.

[Cashell]

Sometime ago, I read somewhere that they borrow into soil deep enough to avoid frost.

[Dumbledore]

Hmmm... Wreckoning, I want the results.
And that's interesting... I might have to put a box of soil outside over winter and collect some sluggies!

[Cashell]

Nov 4, 2013 23:54:20 GMT wreckoning said:

It's something not understood by science at this time, as far as I have read. We do know that slugs can and do survive canadian winters.

In regards to the eggs, they can survive the winter as well, which confuses me because aren't we freezing the eggs of slugs we don't have room for? In which case are we certain that freezing is really killing them? I plan to run some tests freezing eggs for different lengths of times and then seeing if they hatch.

I'm thinking that this must be a survival mechanism for slugs that have lived in harsh climates for thousands of years.

[malacophile]

Slugs and snails both, as well as their eggs, seem to survive the winter remarkably well. Last year, I went to visit my parents a few hours north of here during the winter. Despite the relatively meager distance, it was considerably colder. Nonetheless, I tried looking for slugs and snails and was shocked by how many I found, across five different species no less. They weren't very well protected, and it was below freezing outside (below 32F in the states). This conflicts with many things I've read about how adult slugs and snails don't winter over and that only the babies survive. Well, I found them ranging from egg to hatchling to full maturity.

Even where my parents live now, In northern Wisconsin where it can reach 20F below in the winter, my mother has told me she's seen adult slugs and snails in hiding, but still very much alive.

Yet when I freeze my fulica and other snail/slug eggs, they fail to hatch after I remove them from the freezer, which only goes to 32F. I've tried it several times to no effect. The eggs just sit there doing nothing. I can't think of any reason why this is, but it's a fascinating topic. If only there were a way we could find out the precise mechanism and the various cofactors that affect it.

[moon]

Malacophile,

As you seem to know quite a lot on this subject, I'm wondering if you could take a look at my Baby snails hibernation thread, as no-one has posted any replies!

I would appreciate your opinion.

Thanks.

[muddydragon]

I only really know about freezing in plants in detail but i would be suprised if there wasn't some similar things in snails. I would suspect acclimation is involved. If you freeze snails/slugs/eggs without an acclimation period of colder weather first they may well die when normally they could survive the colder weather, entering a dormant state (or hibernation) could be key in this, reducing metabolism so that the cooler temperatures do not affect them, some animals produce a form of antifreeze in their blood (don't know about slugs/snails) which prevents their bodies from actually freezing. With your egg experiments remember in the wild they are buried in the ground, ground, except in very harsh weather, usually does not freeze to particularly deep down, so eggs in soil in the freezer is not really representative of the freezing stress eggs may experience in the wild (as they could well, if deep enough, not be subjected to any freezing stress atall even in very harsh winters)

Good luck

[muddydragon]

Here's a couple of sbstracts on freezing one on Helix aspera and one on Deroceras reticulatum (the first one is a nicer read), but in summary over 50% of their body can freeze with no damage but not for a great length of time.

I haven't spotted anything on the mechanism by which they tolerate this freezing yet though.


here's an abstracts on freezing in H. aspera:

Tolerance of ectothermic animals to freezing is often estimated by assessing survival a few days after the treatment. However, in the long term, ice formation in the body tissues can affect survival, as well as reproductive capability and growth. The land snail Helix aspersa survives only short durations with ice in its tissues, to a lethal limit of 40 to 60 % of its body water frozen. Adult and immature snails were treated during their winter dormancy period to a freezing event above this limit; their survival was observed both in the short and long term, as well as their ability to reproduce (adults) and grow (immature snails). Treated snails were compared with a control group, which was not frozen. No difference appeared in the survival, reproduction and growth of control and frozen snails. This study confirms partial freezing tolerance in this population of Helix aspersa. (http://www.ingentaconnect.com/content/cryo/cryo/2002/00000023/00000004/art00008)


one on sugs:
Cold hardiness of ectotherms has been widely studied in arthropods, but there is a more limited literature on the survival of molluscs at low temperatures. A number of intertidal species have been examined in detail, but terrestrial molluscs have largely been overlooked until recently. This paper reports results of laboratory experiments to evaluate the cold hardiness of the terrestrial slug, Deroceras reticulatum . The mean supercooling point (SCP) rose from -4.2° C in summer to -3.6°C in winter. The SCP that caused 50% mortality (LSCP50 ) remained constant at -4.7 to -4.8°C in both seasons, but slugs were able to survive the frozen state for longer in winter (LD50 of 31.8 minutes compared with 17.0 minutes in summer). Slug survival at freezing temperatures was prolonged to at least five hours when placed on a moist, absorbent substrate. D. reticulatum exhibits partial freeze tolerance, with an increased survival in winter. The results are discussed in relation to the slugs' natural environment (http://www.ingentaconnect.com/content/cryo/cryo/2004/00000025/00000003/art00005)

[wreckoning]

Quite interesting muddy, thanks for the links! You've no doubt saved the lives of some of my poor slugs which were about to become test subjects.

[muddydragon]

well i hope you tell them to appreciate it

Have a root round on google scholar you might be able to find more info