Cockroaches are terrestrial insects and cannot breathe underwater. Their respiratory system is not designed to extract oxygen from water, unlike aquatic animals such as fish. This fundamental difference means that prolonged submersion eventually leads to a lack of oxygen for these insects.
How Roaches Breathe
Cockroaches possess a specialized respiratory system adapted for life on land, differing significantly from the lungs found in mammals. Instead of lungs, they breathe through a network of tubes called tracheae. These tracheal tubes branch throughout their body, delivering oxygen directly to their tissues and cells.
Air enters this system through small openings located along the sides of their body, known as spiracles. There are typically ten pairs of these spiracles, which function as entry and exit points for gases. These spiracles can be opened and closed, allowing the cockroach to regulate airflow and prevent unwanted substances, such as water, from entering its respiratory system. This direct delivery of oxygen to cells means their blood does not transport oxygen, unlike many other animals.
Roach Survival in Water
Despite their inability to breathe underwater, cockroaches can survive submersion for extended periods. This is largely due to their capacity to close their spiracles, effectively holding their breath and preventing water from entering their tracheal system. This ability allows them to remain submerged for a surprising duration, often up to 30 to 40 minutes.
Their low metabolic rate further contributes to their resilience in oxygen-limited environments. A slower metabolism means they require less oxygen, enabling them to conserve the oxygen already present in their tracheal system. Additionally, some species, such as the American cockroach, can trap air within their bodies, which aids in buoyancy, allowing them to float rather than sink when submerged.
Why Drowning Roaches Isn’t Easy
Drowning cockroaches is a challenging task. Their ability to seal their spiracles prevents water from entering their respiratory system, acting as a natural defense mechanism against submersion. This allows them to survive without external oxygen intake for a considerable time.
Due to their capacity to hold their breath and float, simply flushing a cockroach down a drain often proves ineffective. They can survive brief submersion and may even navigate pipes, potentially resurfacing elsewhere in the plumbing system or entering sewer lines. Prolonged and complete submersion, sometimes for several hours, is typically needed to ensure their demise.