Why don't lice drown? - briefly
Lice remain afloat because their bodies are coated with a water‑repellent wax that prevents wetting, and they can trap a thin layer of air with their legs and body shape. This adaptation allows them to move on the water surface without becoming submerged.
Why don't lice drown? - in detail
Lice survive immersion because their anatomy prevents water from entering the respiratory system. The exoskeleton is coated with a waxy layer that repels moisture, creating a barrier that limits water penetration. Spiracles, the openings through which air reaches the tracheae, can close tightly, sealing the internal air supply. This closure, combined with the low metabolic rate of the insect, allows oxygen reserves to last for extended periods without external airflow.
Additional factors contribute to their resilience in water:
- Surface tension supports the insect’s small body, enabling it to float temporarily on the water film that forms on hair shafts.
- Strong claws grip hair strands, preventing displacement by water currents.
- The cuticle’s hydrophobic properties reduce the amount of water that adheres to the body, minimizing the risk of drowning.
- Lice can enter a state of reduced activity when submerged, lowering oxygen consumption until conditions improve.
Empirical observations show that lice can remain viable after several hours of submersion, provided the environment remains warm and the insects retain access to a trapped air pocket. Prolonged exposure to water without the ability to close spiracles or without the protective waxy coating leads to mortality, confirming that the combination of physical barriers and behavioral adaptations is essential for their survival under wet conditions.