Spiders, like all living organisms, respond to environmental conditions. While they don’t experience “cold” emotionally like humans, they react physiologically and behaviorally to temperature drops. Their survival depends on biological processes that help them cope with thermal challenges. This adaptability allows them to persist in diverse climates.
How Spiders Sense Temperature
Spiders are ectothermic, meaning their body temperature is directly influenced by their surroundings. They detect temperature changes using specialized sensory organs called thermoreceptors. These receptors are typically found on their legs, particularly on the tarsal segments.
These thermoreceptors are highly sensitive, detecting temperature differences as small as 0.4°C in some species. This precise detection is a physiological response, enabling the spider to gather information about its thermal environment. Sensing subtle temperature shifts guides their actions and internal adjustments.
Behavioral Responses to Cold
When temperatures fall, spiders employ various behavioral strategies to avoid extreme cold. Many species seek sheltered microhabitats that offer insulation and protection. These refuges include spaces under rocks, within leaf litter, beneath tree bark, or inside crevices.
Some spiders may seek shelter indoors as autumn progresses. Basements, attics, and other undisturbed areas within homes provide stable, warmer environments. This indoor migration helps them escape harsh outdoor conditions. Many species also reduce activity, entering dormancy or torpor to conserve energy.
Physiological Adaptations for Cold Survival
Spiders possess internal biological mechanisms to survive cold temperatures. Many species synthesize “antifreeze” compounds, known as cryoprotectants, in their hemolymph (the spider equivalent of blood). These include substances like glycerol, trehalose, and other polyhydroxy alcohols and carbohydrates. These cryoprotectants lower the freezing point of their body fluids, preventing the formation of ice crystals within their cells and tissues.
Another adaptation is supercooling, where body fluids remain liquid even at temperatures below their typical freezing point. For instance, some wolf spiders can supercool to -7°C due to elevated glycerol concentrations. Spiders can also undergo metabolic suppression, reducing their metabolic rate to conserve energy during cold periods. This can be a reduction of up to 90% in some orb-weaver spiders.
Impact of Freezing Temperatures
Despite their adaptations, spiders have limits to their cold tolerance. When temperatures drop too low, even with cryoprotectants and supercooling, ice crystals can form within their bodies. This intracellular freezing is lethal. Ice crystal formation causes physical damage, rupturing cell membranes and disrupting physiological functions.
The temperature at which spontaneous freezing occurs in a spider’s body fluids is known as its supercooling point. While some species can tolerate sub-zero temperatures, prolonged exposure below their specific thresholds leads to cell damage and ultimately death. The survival of a spider species is directly linked to these lethal temperature limits, which can vary depending on the species and its native climate.