How do Insects Breathe? 6 Quick Answers You Should Know
Almost all living organisms on earth need oxygen to survive. This element plays a vital role in cellular respiration, energy production, and metabolism. Without oxygen, living beings wouldn’t be able to grow, turn food into energy, or reproduce.
Needless to say, oxygen is pretty important. But not all animals get their oxygen in the same way. Not every being in the animal kingdom uses the same organs to breathe.
But all need to intake oxygen into their bodies somehow. This includes all animals, from largest to smallest. And since insects belong to the animal kingdom, they also rely on oxygen for cellular respiration and metabolism. But it’s not so straightforward.
Some facts about insect respiration might surprise you. In this article, we’ll cover everything in depth. So, if you’re curious to learn more about this subject, keep reading! You’re in for some big surprises.
Do Insects Breathe?
Insect anatomy is completely different from that of other animals, but one thing remains true. Insects need oxygen to live. And as any other living being on earth, insects must rely on respiration to get the oxygen that they need inside the body. But they don’t really breathe in the way that humans or other animals do. The way they do it is very different and interesting.
Unlike other animals, insects don’t have a nose. Instead, they have multiple small holes all over the sides of their bodies. They’re organized in pairs of two, and they can be found on each segment of an insect’s abdomen.
These holes are called “spiracles” and they can open and close to regulate the exchange of gases in an insect’s body. Oxygen comes in through the open holes, and carbon dioxide travels back out.
Maintaining the perfect balance between these two gasses is crucial. While insects need oxygen, there can be too much of a good thing. Oxygen can become toxic to insects if they get too much of it inside the body. Insects also have a different breathing rhythm than other animals. With so many holes across the body, they can get a lot of oxygen very quickly.
To avoid oxygen toxicity, they must breathe slowly and discontinuously. This is the main reason why insects can last a long time without breathing. While a human will suffocate in just a few minutes without oxygen, some insects can keep living for hours even when deprived of oxygen (more on this later).
Do Insects Have Lungs?
If you thought not having a nose was weird, imagine breathing with no lungs. That’s exactly what bugs are doing. They don’t have lungs, because they don’t need them. But how exactly does any of this work? Well, let’s look at a comparison between bugs and humans to get a better idea.
Humans are obviously a lot larger than bugs, thank God for that! Because our bodies are so large, we need a lot of oxygen, and we need it fast. Our lungs come in handy because they make the uptake and delivery of oxygen quick and easy.
We breathe in, the air travels into our lungs, and then the oxygen enters the blood. The oxygen-rich blood then travels to all the tissues in the body in a matter of seconds.
Bugs don’t need as much oxygen, because their bodies are so much smaller. As we’ve discussed previously, too much oxygen can actually be toxic for bugs. So, having lungs would be overkill for a bug. Instead, bugs can get oxygen directly to their muscles and other tissue.
There’s no need for blood to do that job. The spiracles on the body just open to let oxygen pass and travel to the body’s tissues.
Unlike humans, bugs don’t require any mechanical action to breathe. Instead, they just let the oxygen slowly travel inside the body. This process is called diffusion. This seems to be working pretty well for bugs.
However, not having lungs and relying on diffusion to breathe means that insects are highly dependent on the atmospheric oxygen concentration. So, the less oxygen in the air, the more difficult it is for insects to breathe properly.
What Is the Tracheal System?
The tracheal system is the name of the internal respiratory system specific to bugs. It’s made up of a complex network of tubes, called tracheae, which help with the delivery of oxygen directly into the insect’s bodily tissues. Unlike in other animals, the respiratory system in bugs is separate from the circulatory system.
The blood doesn’t transport oxygen throughout insects’ bodies. That’s the job of the tracheal system. The oxygen enters the tracheae through small openings (spiracles) in the exoskeleton. These openings are connected to muscles and they act like valves.
An insect can open or close them through muscular contraction to let the air flow in or out of the body. Beyond the surface, the tube-like tracheae connect directly to these openings.
These tubes form a complex ramified network of smaller and smaller tubes. While there’s a limited number of openings on an insect’s abdomen, the tracheae connected to them have many offshoots that travel all over the body. Think of it as a tree with a large trunk and smaller and smaller branches towards the top.
At the end of each tracheal “branch”, there’s a cell called the “tracheole”. This tracheole has a thin, moist membrane. Once the oxygen has reached the end of the tracheal branch, it diffuses through the tracheole’s membrane to travel into the tissues. There, the oxygen is used for energy by the mitochondria, the powerhouse of the cell.
Can Insects Breathe Underground?
Insects don’t need as much oxygen as larger animals. This means they can also live underground for extended periods without suffocating. The amount of time an insect can survive without fresh oxygen depends on its body size, species, and soil aeration. Overall, insects can breathe underground just fine.
Entomologists hypothesize that the slow and discontinuous breathing of insects is actually an adaptation to their living in such conditions. Perhaps insects breathe at different rates when above versus below the ground. Either way, soil-dwelling insects don’t seem to suffer from hypoxia or carbon dioxide poisoning.
Because they can go for long periods of time without intaking oxygen, they can avoid hypoxia even when underground, where the oxygen concentration is lower. Some insect species might die quickly in hypoxic conditions, while others can go for extended periods without fresh oxygen. For example, some Cicada species can live down there for up to 17 years!
I should also mention that the soil itself isn’t oxygen-free. In fact, the soil is constantly exchanging gases with the atmosphere. In the atmosphere, there’s around 21% oxygen and just 0.036% carbon dioxide. The air in the soil, while lower in oxygen, is not completely devoid of it. It contains just enough for insects to breathe comfortably.
At the same time, while insects are moving, feeding, and breathing underground, they also help the soil breathe at the same time. The burrows and tunnels created by insects help the oxygen travel deeper into the ground. How’s that for natural soil aeration?
Can Insects Breathe Underwater?
Some insects can breathe underwater. Others, not so much. However, most insects can survive for a prolonged time when submerged in water. Because they can intake a lot of oxygen relative to body size, insects can last for minutes to hours without breathing. As long as the spiracles on the body are closed when the bug enters the water, the insect won’t drown.
Aquatic insects have developed a special ability to trap oxygen in water bubbles on their exoskeleton. This is how they can submerge themselves into the water and intake oxygen at the same time. The bubble forms a protective barrier that allows the insect to open its spiracles to breathe without becoming inundated.
These insects can spend an indefinite amount of time underwater at a depth as low as 98 feet. As long as these bubbles don’t burst, aquatic insects can breathe safely. But how do they create these bubbles? Aquatic insects have a rough coat that repels water efficiently. The hairs and wax-like coating on the insect’s body also keep the spiracles protected.
The repellant action of their coat pushes the water away from the spiracles, forming bubbles along their abdomens. Underwater, these bubbles work like an artificial external lung. They keep oxygen trapped inside. They also act as a membrane, letting oxygen from the water pass through. So, the bugs got an infinite supply of the good stuff.
How Long Can Insects Survive Without Oxygen?
The answer’s going to depend on multiple factors. The most important things to consider are the insect’s species, its growing stage, how much oxygen it already has circulating in its tracheae, and the oxygen concentration in the air around them. Most insects can survive for extended periods without intaking fresh oxygen though. We’re talking about insects holding their breath for hours or even days.
This is possible because insects have smaller bodies and very low metabolic rates. They can close their spiracles to preserve and recycle the oxygen inside the body. And because they can store a lot of oxygen inside relative to their body size, this increases their odds of survival in hypoxic conditions. However, no bug can live without fresh oxygen indefinitely.
While holding their breath, insects use up the oxygen circulating through their tracheal system. Once all the oxygen within the body has been recycled, the bug starts suffocating. How long would that take though? Let’s see some concrete examples. Studies on beetles and butterfly pupae have shown that these bugs can survive for a few hours without breathing.
An even more impressive example is the corn rootworm larva, which can last up to 42 hours in low oxygen conditions. Depriving a fly of oxygen would lead to suffocation in 4-8 hours. Other insects, like roaches, will only last up to 7 minutes when starved of oxygen. There’s a lot of variation in hypoxia survival rates when it comes to bugs.
The insect world might be small, but that doesn’t make it any less interesting. As we’ve observed today, bugs are capable of some impressive feats we never expected. As we study them more closely, we learn more and more surprising things about them.
Breathing without lungs, breathing underground and underwater, and even surviving up to 42 hours without oxygen— these might sound like things out of a sci-fi movie for us. But they’re just part of daily life for insects.
Bugs have evolved an intricate and highly efficient respiratory system that allows them to do all this. Their abdominal spiracles and the complex ramified tracheae traveling throughout their bodies help the bugs deliver oxygen straight to the cells of each bodily tissue. This makes them highly efficient in storing and recycling oxygen inside their bodies.