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Bryan Reynolds/Getty ImagesThe respiratory process in insects differs significantly from that of humans. Unlike us, who rely on lungs to gather oxygen and a circulatory system to distribute it, insects utilize a network of intricate tubes known as the tracheal system. This system transports oxygen directly to every cell in their bodies. Picture yourself as an oxygen molecule in the air, about to be inhaled by an insect.
- You enter a small opening on the insect's thorax or abdomen, known as a spiracle
. This spiracle leads to a lengthy tube called a trachea.
- You travel down the trachea, an air-filled, branching tube.
- You navigate through the branches until you arrive at a minute, fluid-filled endpoint called a tracheole.
- You dissolve into the fluid.
- From the fluid, you diffuse or move across the tracheole wall into an insect cell, such as a muscle cell.
In most insects, air movement through the tracheal system depends entirely on diffusion. Since diffusion works best over short distances, insects cannot grow to enormous sizes. You won't encounter giant ants, like those in the movie "Them," because air couldn't diffuse far enough into their bodies to sustain their cells. However, some larger insects can use their abdominal muscles to pump air in and out of their tracheal systems to a limited extent.
Given this respiratory system, suffocating an insect would be challenging. However, if water fills the tracheal system, the diffusion of air slows significantly. As a result, insects can drown relatively easily.
