Crawfish, also known as crawdads or crayfish, are freshwater crustaceans found in streams, lakes, and marshes across the globe. These animals are fundamentally aquatic, using gills to breathe dissolved oxygen from the water. Despite their dependence on an aqueous environment, many species possess a surprising ability to survive and even travel on land for a temporary period. This terrestrial capability is usually a response to changing environmental conditions, such as seeking new habitats or escaping low oxygen levels in their current water source.
The Time Limit for Survival
The actual duration a crawdad can survive outside of a water body is extremely variable, ranging from a few hours to several days under non-ideal conditions. For most stream-dwelling species, being isolated from water in a dry environment will result in death within a day or two due to rapid desiccation. This timeframe is often the limit for crawfish transported for commercial purposes or those found stranded on dry land.
The upper end of the survival range is dramatically extended for species adapted to burrowing or living in environments prone to drought. Certain species, such as the Yabby (Cherax destructor) or some terrestrial crayfish, can survive for weeks or even months within damp, sealed burrows. Even under laboratory conditions, studies show significant variability in desiccation tolerance among different species, with survival times ranging from approximately 20 hours to over 120 hours for some native crayfish.
How Crawdads Breathe Out of Water
A crawdad’s ability to survive on land is tied to its gills, which are housed within protective chambers on the sides of the carapace. Unlike the lungs of terrestrial animals, these gills are not designed to interact directly with dry air. Gas exchange requires a thin layer of moisture to dissolve oxygen before it can pass through the gill membrane into the bloodstream. When the crawdad is out of water, the surrounding carapace helps to seal the branchial chambers, retaining a store of water and moisture around the gills. The primary cause of death when a crawdad is stranded is not a lack of oxygen, which is abundant in air, but the failure of this gas exchange mechanism once the gills dry out and the respiratory surfaces collapse.
Environmental Factors Affecting Longevity
The conditions of the terrestrial environment play a decisive role in pushing a crawdad’s survival time to its maximum potential. High levels of atmospheric humidity are the single most important factor, as moist air slows the rate of water loss from the gills and the body surface. When the air is saturated with moisture, the crawdad can effectively breathe for a much longer period, allowing them to cross large distances on land. Temperature also significantly influences longevity, primarily by controlling the crawdad’s metabolic rate. A lower ambient temperature reduces the animal’s need for oxygen and slows the rate of water evaporation from the gill chambers. Conversely, high heat will accelerate metabolism and increase water loss, drastically shortening the time a crawdad can survive outside of water.
The presence of a moist substrate, such as damp soil, mud, or wet moss, is also highly beneficial because the crawdad can press its body against it to absorb external moisture and replenish the water in its gill chambers. Species-specific adaptations further modify these limits, as burrowing species have evolved a greater tolerance for desiccation compared to those that live exclusively in open water. These hardy crawdads can dig deep burrows that reach the water table or a perpetually saturated layer of earth. By sealing themselves within these burrows, they create a personalized microclimate with near-100% humidity, protecting them from predators and drought conditions.