Ants exhibit surprising resilience to water, an adaptation rooted in their unique physiology and social behavior. An ant can survive in water for a limited period, but the distinction between short-term submersion and long-term failure is important. While an individual ant can endure being underwater for hours or even days, a permanent inability to breathe ultimately leads to death.
Individual Ant Physiology and Submersion
The primary mechanism for an ant’s short-term survival underwater lies in its respiratory system, which differs significantly from that of mammals. Ants do not possess lungs; instead, they breathe through tiny openings called spiracles, positioned along the sides of their bodies. These spiracles connect to an internal network of tubes that distribute oxygen directly to the tissues.
When submerged, an ant can actively close these spiracles, sealing off its respiratory system from the surrounding water. This action allows the ant to “hold its breath” and prevents water from flooding its internal tracheal tubes. The ant’s outer layer, the cuticle, is coated in a waxy, water-repellent substance, making it hydrophobic.
This hydrophobic coating helps trap a thin layer of air, called a plastron or air bubble, against the ant’s body when submerged. The trapped air functions as a temporary oxygen reserve, sustaining the ant while its spiracles are closed. This bubble also contributes to the ant’s buoyancy, preventing it from sinking. This protective air layer allows an individual to endure being underwater for a substantial time.
Factors Determining Survival Time
The time an ant can survive submerged varies and depends on environmental and biological factors. Species is a determinant; some ants last only a few hours, while others, like certain carpenter ant species, survive for up to two weeks in laboratory conditions. Most common ant species endure submersion for around 24 hours.
Water temperature plays a role in extending this survival period. Colder water causes the ant’s metabolic rate to drop, inducing a state similar to torpor. This reduction in activity conserves the limited oxygen supply trapped in the plastron and slows the physiological demand for air.
The trapped air bubble is not a permanent solution, as the oxygen within it is slowly consumed. For extended survival, the air layer must function as a physical gill, allowing oxygen dissolved in the water to diffuse into the bubble. If the water is warm or lacks sufficient oxygen, the supply depletes faster, and the ant eventually succumbs to a lack of breathable gas.
Collective Survival: Ant Rafts
When faced with large-scale flooding, certain species, notably the fire ant (Solenopsis invicta), exhibit a collective survival strategy known as the ant raft. Thousands of individuals rapidly link their bodies together to create a buoyant, watertight structure that floats on the water’s surface. This behavior is a cooperative effort where ants grasp onto each other using their mandibles and legs.
The raft functions as a self-assembled, super-hydrophobic surface that prevents water from penetrating the structure. The collective nature enhances the ant’s water-repellent properties, trapping a large volume of air between their linked bodies to increase buoyancy. Surface tension also contributes, as the collective mass creates a meniscus effect that helps pull the individuals together and keeps the structure afloat.
The colony’s most vulnerable members, including the queen and the developing young (brood), are positioned in the center or on top of the raft to keep them dry. The ants forming the bottom layer remain submerged, providing a stable, protective base for the rest of the colony. This specialized, living structure allows the entire colony to remain afloat and survive for days or weeks until they encounter dry land.