Ants exhibit remarkable abilities when confronted with water. While they do not “swim” in the traditional sense, their bodies possess unique adaptations that allow them to endure partial or full submersion for varying lengths of time. This resilience stems from physical properties and physiological responses, enabling individual ants and entire colonies to persist in aquatic environments.
Ants’ Unique Water Repellence
An ant’s ability to withstand water begins with its outer layer, the cuticle. This exoskeleton is covered in a waxy, hydrophobic coating. This waxy surface prevents water from adhering directly to the ant’s body, causing water droplets to bead up and roll off.
Tiny hairs on the ant’s body further enhance this water-repellent property. These microscopic hairs trap a thin layer of air around the ant when submerged, creating a “plastron.” This trapped air bubble acts as a physical gill, providing temporary oxygen and reducing its density, allowing it to float. This buoyancy is crucial for survival during encounters with water.
Breathing Underwater and Surviving Submersion
When an ant finds itself fully submerged, its survival mechanisms extend beyond water repellence. Ants do not possess lungs; instead, they breathe through tiny openings called spiracles. These spiracles connect to an internal tracheal system, which facilitates gas exchange. Ants can close these spiracles, preventing water from entering their respiratory system. This allows them to “hold their breath” for extended periods.
In addition to closing their spiracles, ants can reduce their metabolic rate while submerged. This state of suspended animation, or torpor, lowers their oxygen demand, requiring 20 times less oxygen than when active. The duration an ant can survive underwater varies by species and environmental factors like water temperature, which influences metabolic rate and oxygen availability. Some species can endure submersion for up to 24 hours, while others have been observed surviving for as long as 14 days.
Colony Survival in Flooded Environments
Beyond individual resilience, ant colonies, particularly fire ants, demonstrate collective strategies for surviving flooding events. When their underground nests become inundated, these ants work together to form living rafts. This cooperative behavior involves thousands of ants linking their legs and mandibles, creating a buoyant and waterproof structure.
The raft protects vulnerable colony members, such as the queen and developing brood (eggs, larvae, and pupae), by positioning them within the center or at the bottom where trapped air provides buoyancy and oxygen. Worker ants continuously rotate positions within the raft, ensuring no single ant is submerged for too long, with individuals at the bottom periodically moving to the top for air. These self-assembling rafts can remain afloat for several days, up to 12 days, until they reach dry land or an elevated object where the colony can disembark and establish a new home.