Snails and slugs thrive on warm summer nights accompanied by gentle rainfall. However, their presence notably diminishes with the onset of winter. Despite their tendency to seek refuge from extremely cold conditions, snails and slugs have weathered thousands of winters. This begs the question, just how cold is too cold for snails?
Cold-tolerant snails undergo lethal changes at about 20.12°F (-6.6°C), with a deviation of 30.56°F/33.44°F (+/-0.8°C), while non-acclimated snails are affected at around 19.22°F (-7.1°C), 34.7°F/29.3°F (+/-1.5°C). Even temperatures near 32°F (0°C) can be too cold for snails, causing some to perish.
Snails are acutely aware of the harmful effects of exposure to cold, hence their tendency to hibernate during winter. This article delves into the temperatures considered too cold for snails and slugs and provides guidance on how to care for your pet snails under such conditions.
Understanding Cold Tolerance in Snails
Cold tolerance refers to an organism’s ability to maintain its body temperature even as surrounding environmental temperatures decrease. This is achieved through various mechanisms, such as heat production or seeking insulation.
Typically, mollusks like snails, classified as ectothermic animals, depend on the external environment to regulate their body temperatures. However, this inability to internally regulate temperature subjects them to the fluctuations of the prevailing weather conditions.
Nevertheless, snails have evolved to withstand water temperatures below the freezing point of 32°F (0 °C). Despite this, the cold tolerance of snails and slugs is relatively low, usually equating to the maximum ambient air temperatures. Without survival strategies like hibernation or heat production, they may not survive.
Slugs, lacking the protective shell of snails, are even more susceptible to cold temperatures. The snail’s shell is a refuge during threats or harsh cold conditions. Conversely, slugs, lacking this protective shell, remain directly exposed to the cold environment.
Related Reading: Do Snails Need a Heater?
How Have Snails and Slugs Survived a Million Winters?
Snails and slugs have persistently evolved their survival strategies to cope with harsh cold temperatures. These adaptations have enabled them to endure even the most severe winters.
Commonly, snails and slugs avoid extreme hot and cold weather by entering a state of torpor or hibernation. Torpor, experienced by ectotherms, is a state that occurs when external temperatures suddenly drop, even outside of the winter season.
When it gets cold, ectotherms like snails and slugs slow down or halt their metabolism until the threat of cold passes. However, torpor is a short-term solution to cold temperatures, typically lasting only a night or a few hours.
During winter, ectotherms such as snails hibernate, essentially taking a season-long rest. During this hibernation, ectothermic animals reduce their metabolic rates to approximately two percent and only re-emerge when the weather warms up.
Do Snails and Slugs Hibernate Differently?
Snails and slugs hibernate when winter arrives or when external temperatures become unbearable. However, the hibernation methods of these two related creatures are distinctly different.
An engaging account from writer Phil Gates, captured during a walk in the forest, illustrates this difference. When bending to tie a loose bootlace, Gates stumbled upon a mollusk hibernaculum, a Latin term describing a winter quarter tent that animals use as a cold refuge.
He noticed hundreds of garden snails lodged within the crevices of a dry-stone wall. Stuck tightly and unmoving in these tiny spaces, the snails were held onto the rock surface by a layer of solidified slime. Besides adhering to the rock surface, the snails were sealed within their helical shells.
This observation by Gates provides first-hand insight into snail hibernation. They remain immobile throughout the season, breaking the seal on their shell fronts only when external temperatures become more hospitable.
While slugs and snails exhibit similar behaviors, a significant difference lies in the lack of a protective shell in slugs. They rely heavily on slime for protection and locomotion.
To escape the cold winter, slugs resort to a different tactic, given their shell-less state. When it gets excessively cold, slugs burrow deep into the ground and hibernate underground throughout the winter. This approach protects them from freezing, as temperatures seldom drop below 32°F (0°C) underground.
However, certain slug species have adapted to winter in a unique way. They don’t need to burrow underground when the environmental temperature falls. Their life cycles have evolved to survive any winter temperature.
These slugs spend the winter as eggs and only hatch with the advent of spring and summer when the climate is warmer and more favorable. These survival strategies ensure the continued existence of slugs. Even if older slugs perish in the cold, new slugs emerge at the end of the cold season, guaranteeing the survival of their species.
Summary
Snails and slugs can withstand temperatures down to 32°F (0°C). However, these mollusks cannot endure temperatures as frigid as 21.2°F (-6°C). Despite these limitations, mollusks have weathered the coldest winters and have thrived for millions of years.
Various studies suggest that ectotherms rely on mechanisms such as heat production or hibernation to endure harsh winter seasons. During this period, these animals slow down or decrease their metabolic rates, remaining dormant until the severe cold abates.
Frequently Asked Questions
At what temperature do snails hibernate?
In general, snails begin to hibernate once temperatures dip below 60°F (15°C), often after the onset of the first frost. This survival strategy allows them to endure the harsh, colder conditions that are characteristic of winter months.
Do snails like warm or cold water?
Snails generally prefer warm water conditions. For freshwater snails, the optimal temperature range is between 72 to 82 degrees Fahrenheit (22 to 28 degrees Celsius), and many saltwater snails have similar temperature preferences.
How long do snails hibernate?
Snail hibernation can vary greatly in length, spanning from just a few days to several months or even years, often aligning with winter or periods of unfavorable conditions. Remarkably, some land snails have been reported to hibernate for up to three years, demonstrating an extraordinary level of endurance.
Sources
- AZ Animals: Where Do Slugs Go in the Winter?
- ScienceDirect: Contributions to Thermal Physiology
- The Guardian: Country Diary: Stumbling Across the Snails’ Winter Shelter
- ThoughtCo: What Does Ectothermic Mean?
- University of New England: Hibernation: Endotherms
