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How do Insects Breathe?

Tricia Christensen
Tricia Christensen
Tricia Christensen
Tricia Christensen

Oxygen is one of the most important molecules needed for growth and to sustain life. Humans and other mammals take in oxygen through respiration. We breathe and inhale oxygen into our lungs, which then disperses oxygen to all tissues via blood blood flow. Other creatures in our world clearly do not have lungs, so they cannot use this method for dispersing oxygen through their bodies. In particular, the way insects breathe is interesting to study.

Insects breathe or gather oxygen through a branched network of tubes called tracheae. These tubes have openings, called spiracles, located on the thorax (chest) and abdomen. Oxygen passively enters spiracles, flows down the tubes, and ends up in liquid located at the bottom of each tube that helps the oxygen dissolve. This liquid then moves into other cells, to provide oxygen to other cells in the insect body.

Microscopic observation revealed that insect breathe air through their mouths.
Microscopic observation revealed that insect breathe air through their mouths.

You can see, under microscope, insects breathe or take in air through their mouths, but they seldom yawn. And this air through the mouth doesn’t provide needed oxygen to the cells because insects lack lungs. Instead of using air in the mouth to supply lungs with oxygen, it can be said that insects breathe passively. They must rely on oxygen around them entering their spiracles, making way down their tracheae to provide needed oxygenation of all their cells.

What makes the subject of how insects breathe fascinating is that theoretically, insects in a highly rich oxygen environment could technically become much bigger than today’s modern versions. For example, many paleontologists suggest that a lot of our modern bugs are tiny versions compared to giant insects that may have roamed the earth in prehistoric times. Due to the passive way insects breathe, life can’t be supported when insects are very large, since there would be no way to properly oxygenate all cells. Scientists believe earth used to have much higher oxygen content, however, meaning there was a proliferation of oxygen for insects to take in. This alone could explain why creepy crawlies of the past were very large — they had more available air to “breathe.”

As oxygen levels declined on earth, being of smaller size would have been of advantage to the insect. Since insects couldn’t breathe as much, survival may have been predicated on being more compact to provide healthy oxygenation to all tissues. Though it should be stated that there are still some pretty large insects in the world. They are mostly not, however, as large as those discovered in fossil records.

For instance, the largest dragonfly fossil found was thought to have lived 250 million years ago during the Paleozoic Era. Its wingspan was 30 inches (76.2 cm), and its body length 18 inches (45.72 cm). Clearly the oxygen rich environment and the way insects breathe benefited the early dragonfly, which had a wingspan about as wide as a toddler is tall.

Frequently Asked Questions

How do insects breathe without lungs?

Insects breathe through a network of tiny tubes called tracheae. Air enters the tracheae through openings on the insect's exoskeleton called spiracles. Oxygen travels directly to the insect's tissues via the tracheal system, which efficiently delivers oxygen without the need for lungs, a method that is particularly effective for the small size of most insects.

Can insects control their breathing?

Yes, insects can control their breathing to some extent. They can open and close their spiracles to regulate the flow of air and prevent water loss. This is especially important in arid environments where conserving moisture is crucial. Some aquatic insects can close their spiracles and trap air to breathe underwater for extended periods.

Do all insects have the same number of spiracles?

No, the number of spiracles an insect has can vary. Typically, an insect has a pair of spiracles per body segment, amounting to anywhere from 3 to 10 pairs along the thorax and abdomen. The exact number and arrangement of spiracles can differ between species, reflecting their diverse lifestyles and respiratory needs.

How do insects' respiratory systems differ from those of humans?

Insects have a respiratory system that is vastly different from humans. While humans use lungs and a diaphragm to pump air in and out, insects rely on their tracheal system, which allows for direct gas exchange with body cells. This system is more efficient for their small size and doesn't require a circulatory system to transport oxygen.

What adaptations do aquatic insects have for breathing?

Aquatic insects have evolved various adaptations for breathing underwater. Some carry a bubble of air with them when they dive, which acts like a physical gill, allowing gas exchange with the surrounding water. Others may have specialized structures like gills or siphons to extract oxygen directly from the water, demonstrating remarkable adaptability.

How does an insect's breathing change during different life stages?

An insect's breathing can change dramatically during its life cycle. For instance, aquatic larvae may have gills, while the adult forms breathe air through spiracles. Metamorphosis often involves a complete reorganization of the respiratory system to suit the insect's new environment and lifestyle, showcasing the incredible versatility of these creatures.

Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent AllThingsNature contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

Learn more...
Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent AllThingsNature contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

Learn more...

Discussion Comments

anon956080

Would it be theoretically possible for a species of insect to evolve a one-way breathing mechanism for much improved efficiency? One trachea tube for oxygen inhalation and another for carbon dioxide exhalation?

I’d really like to hear from an expert. The two spiracles on each segment lends itself quite nicely for this potential evolution of increased oxygen intake ability.

anon92522

@kindaDM: I live in Florida, and yes, those huge cockroaches a can get huge. I tried to step on one and it grabbed my foot.

wwfan

I think it's funny that insects yawn.

curiousDJ

I can't imagine living in a world where insects are two and a half feet wide.

Does the decrease in oxygen in our atmosphere because of global warming make the bugs smaller? I'd be OK with that.

kindaDM

The air in Florida must be extremely oxygen rich. Have you seen the flying roaches called Palmetto bugs that live there? They are huge, and have wings! I don't care so much how they breathe- I just want to know how to stop them from breathing without having them get near me.

anon86446

what else can you tell me about how insects breathe? i find your post interesting.

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    • Microscopic observation revealed that insect breathe air through their mouths.
      By: Vasiliy Koval
      Microscopic observation revealed that insect breathe air through their mouths.