Breathing is essential to almost all living beings. Of course, you knew that already. However, while we have all become so conscious about our health today, how many of us actually give a second thought to the process of breathing and respiration? 

Breathing is the most normal and regular activity we perform every minute of the day; even when we are sleeping. The process of breathing is fascinating across living beings. Here, we can take a detailed look at different ways of breathing in three different living beings – humans, birds and grasshoppers. Each of them has a respiratory system that is unique and will give a glimpse of nature’s curious ways. 
 

1. Human Lungs:

Human lungs are part of the body’s respiratory system. The primary function of the lungs is to process the gas exchange for respiration. The lungs take oxygen from the environment and transfer it to the bloodstream. To breathe properly, humans use structures outside of the lungs - the diaphragm, the intercostal muscles (located between the ribs), the abdominal muscles, and sometimes, neck muscles as well.

The diaphragm, a muscle that sits below the lungs, does the majority of the work involved. When the diaphragm contracts, it moves down and provides more space in the chest cavity and enhances the lungs' ability to expand. The pressure inside goes down when the chest cavity volume increases. Then the air is sucked in through the nose or mouth and moves down into the lungs.

Another point worth noting is that the human chest cavity is always at a lower pressure than the outside environment. This is usually 760 mmHg (millimeters of mercury) at sea level.

2. Bird Lungs:

The respiratory system of birds is quite different from that of mammals. Birds do have lungs, but they do not have a diaphragm. The air moves in and out of their bodies through pressure changes in the air sacs. While the air sacs are not directly related to gas exchange, they do help in directing airflow through the lungs in one direction. The muscles in their chest cause the sternum to be pushed outward. Because of this, negative pressure in the air sacs is created which leads the air to enter the respiratory system.   

The lungs of birds do not expand or contract like the lungs of mammals. They have thin-walled, tubular structures called parabronchi that are located throughout the lungs between the secondary bronchi. While the air moves in one direction through the lungs, it also flows in one direction through the parabronchi. Basically, from one secondary bronchus into another.

The respiratory system of birds transfers more oxygen with each breath. It is the remarkable air sacs, though, which really make the respiratory system of birds unique. They enable regular, one-way flow during both inspiration and expiration.

3. Grasshopper Trachea:

You would be surprised to know that grasshoppers have no lungs. Like all insects, they breathe through a complex network of tubules called the tracheae. While the exchange of gases happens through the tracheal system, it is the spiracles where the air is taken in first. This system is comprised of ten spiracles that are located along the length of the grasshopper’s abdomen in eight pairs. They also have two more pairs in the thoracic region.  

Oxygen disperses into their cells directly and then into the atmosphere. This completes the grasshopper’s respiration process. Their spiracles take in air with the control of their brains. Furthermore, they also have a few spiracles that perform the job of expiration of air as well. The tracheae inside humans do the role of cleaning the air. For grasshoppers, this system works as an independent operation and is not involved with the circulatory system.